New upstream version 0.8

2025-12-23 04:55:14 +00:00 · 2021-10-17 11:13:19 +02:00
parent b2567e2868
commit 74aada02ef
23 changed files with 3303 additions and 2276 deletions
--- a/.gitignore
+++ b/.gitignore
@@ -0,0 +1,22 @@
+*.o
+*~
+.deps
+.dirstamp
+/Makefile
+/Makefile.in
+/aclocal.m4
+/autom4te.cache/
+/compile
+/config.h
+/config.h.in
+/config.log
+/config.status
+/configure
+/depcomp
+/doc/*.1
+/install-sh
+/knock
+/knock-*.tar.*
+/knockd
+/missing
+/stamp-h1
--- a/16
+++ b/16
@@ -0,0 +1,16 @@
+Many thanks to everybody who has helped to improve knockd in some way. This is
+a fairly old project, and some contributer names have almost surely been lost
+along the way. Thanks to the unsung heroes too.
+
+- airwoflgh <paul.rogers@flumps.org>
+- catbref <misc-github@talk2dom.com>
+- Diego Elio Pettenò <flameeyes@flameeyes.eu>
+- Dima Krasner <dima@dimakrasner.com>
+- Jonathon Reinhart <jonathon.reinhart@gmail.com>
+- Marius Hoch <hoo@online.de>
+- Michael Weiss <dev.primeos@gmail.com>
+- Oswald Buddenhagen <ossi@kde.org>
+- Sébastien Valat <sebastien.valat@gmail.com>
+- TDFKAOlli <TDFKAOlli@ish.de>
+- Ximin Luo <infinity0@pwned.gg>
+- vriera <Vincent.Riera@imgtec.com>
--- a/2
+++ b/2
@@ -2,7 +2,7 @@
 		       Version 2, June 1991

 Copyright (C) 1989, 1991 Free Software Foundation, Inc.
- 		59 Temple Place, Suite 330, Boston, MA 02111-1307, USA.
+ 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.

 Everyone is permitted to copy and distribute verbatim copies
 of this license document, but changing it is not allowed.
--- a/30
+++ b/30
@@ -1,5 +1,35 @@
 VERSION         DESCRIPTION
 -----------------------------------------------------------------------------
+0.8           - Multiple fixes (#67, #77)
+              - IPv6 support (Sebastien Valat)
+0.7.8         - Fix for Issue #33, #34 and #35 contributed by Alexander
+                Rumyanstev.
+0.7.7         - Fix for Issue #7 & #17 contributed by Michael G<>hler.
+                All IPs assigned to a single interface are now listened on.
+              - Fix for compile warning on OSX where daemon() is deprecated.
+              - Fix for Issue #15 - list.c OpenBSD segfault: change malloc
+                to calloc.
+0.7.6         - Fix for Issue #13 where similar sequences are not detected
+                correctly.
+0.7.5         - Added Greg Kuchyt's knock_add script but updated to be a
+                generic IPTables helper that also deletes rules
+0.7.4         - Patches from Michael G<>hler
+                - Updated gitignore to include additional autoconf files.
+                - Updated Makefile to fix deprecated warning on CPPFLAG
+                  -D_BSD_SOURCE.
+0.7.3         - Patches from Jonathon Reinhart
+                - Fixed PCAP filter for PSH flag detection.
+              - Patches from Christos Triantafyllidis
+                - Updated FSF address.
+0.7.2         - Patches from Paul Rogers
+                - Applied missing fixes from issue #16 - OpenBSD build
+                  issues, reordering of headers, scoping DLT_LINUX_SLL for
+                  Linux only, for -> while loop in sniff() cleanup.
+0.7.1         - Patches from Paul Rogers
+                - Fixed issue #2 - SIGHUP (reload) now listens for new
+                  sequences in the config file.
+                - Fixed issue #26 - knockd now fails if a malformed config
+                  file is read during SIGHUP (reload).
 0.7           - Patches from Oswald Buddenhagen:
                - Document the 'target' configuration directive.
                - Merging OS-specific networking code to reduce LOCs and the
--- a/Makefile.am
+++ b/Makefile.am
@@ -1,12 +1,12 @@
-AM_CPPFLAGS=-D_BSD_SOURCE
-AM_CFLAGS=-g -Wall -pedantic -fno-exceptions
+AM_CPPFLAGS=-D_DEFAULT_SOURCE
+AM_CFLAGS=-g -Wall -pedantic -fno-exceptions -D_BSD_SOURCE

 bin_PROGRAMS = knock
-
 man_MANS = doc/knock.1

 if BUILD_KNOCKD
 sbin_PROGRAMS = knockd
+dist_sbin_SCRIPTS = src/knock_helper_ipt.sh
 man_MANS += doc/knockd.1
 sysconf_DATA = knockd.conf
 endif
@@ -14,9 +14,10 @@ endif
 dist_doc_DATA = README.md TODO ChangeLog COPYING

 knock_SOURCES = src/knock.c
-knockd_SOURCES = src/knockd.c src/list.c src/list.h
+knockd_SOURCES = src/knockd.c src/list.c src/list.h src/knock_helper_ipt.sh

 %.1: %.1.in
 	sed -e "s/#VERSION#/$(VERSION)/" $< > $@

 EXTRA_DIST = doc/knock.1 doc/knock.1.in doc/knockd.1 doc/knockd.1.in knockd.conf
+CLEANFILES = $(man_MANS)
--- a/Makefile.in
+++ b/Makefile.in
@@ -1,7 +1,7 @@
-# Makefile.in generated by automake 1.14.1 from Makefile.am.
+# Makefile.in generated by automake 1.16.3 from Makefile.am.
 # @configure_input@

-# Copyright (C) 1994-2013 Free Software Foundation, Inc.
+# Copyright (C) 1994-2020 Free Software Foundation, Inc.

 # This Makefile.in is free software; the Free Software Foundation
 # gives unlimited permission to copy and/or distribute it,
@@ -15,8 +15,19 @@
@SET_MAKE@


+
 VPATH = @srcdir@
-am__is_gnu_make = test -n '$(MAKEFILE_LIST)' && test -n '$(MAKELEVEL)'
+am__is_gnu_make = { \
+  if test -z '$(MAKELEVEL)'; then \
+    false; \
+  elif test -n '$(MAKE_HOST)'; then \
+    true; \
+  elif test -n '$(MAKE_VERSION)' && test -n '$(CURDIR)'; then \
+    true; \
+  else \
+    false; \
+  fi; \
+}
 am__make_running_with_option = \
  case $${target_option-} in \
      ?) ;; \
@@ -81,14 +92,13 @@ bin_PROGRAMS = knock$(EXEEXT)
@BUILD_KNOCKD_TRUE@sbin_PROGRAMS = knockd$(EXEEXT)
@BUILD_KNOCKD_TRUE@am__append_1 = doc/knockd.1
 subdir = .
-DIST_COMMON = $(srcdir)/Makefile.in $(srcdir)/Makefile.am \
-	$(top_srcdir)/configure $(am__configure_deps) \
-	$(srcdir)/config.h.in depcomp $(dist_doc_DATA) COPYING \
-	ChangeLog TODO compile install-sh missing
 ACLOCAL_M4 = $(top_srcdir)/aclocal.m4
 am__aclocal_m4_deps = $(top_srcdir)/configure.ac
 am__configure_deps = $(am__aclocal_m4_deps) $(CONFIGURE_DEPENDENCIES) \
 	$(ACLOCAL_M4)
+DIST_COMMON = $(srcdir)/Makefile.am $(top_srcdir)/configure \
+	$(am__configure_deps) $(am__dist_sbin_SCRIPTS_DIST) \
+	$(dist_doc_DATA) $(am__DIST_COMMON)
 am__CONFIG_DISTCLEAN_FILES = config.status config.cache config.log \
 configure.lineno config.status.lineno
 mkinstalldirs = $(install_sh) -d
@@ -96,8 +106,8 @@ CONFIG_HEADER = config.h
 CONFIG_CLEAN_FILES =
 CONFIG_CLEAN_VPATH_FILES =
 am__installdirs = "$(DESTDIR)$(bindir)" "$(DESTDIR)$(sbindir)" \
-	"$(DESTDIR)$(man1dir)" "$(DESTDIR)$(docdir)" \
-	"$(DESTDIR)$(sysconfdir)"
+	"$(DESTDIR)$(sbindir)" "$(DESTDIR)$(man1dir)" \
+	"$(DESTDIR)$(docdir)" "$(DESTDIR)$(sysconfdir)"
 PROGRAMS = $(bin_PROGRAMS) $(sbin_PROGRAMS)
 am__dirstamp = $(am__leading_dot)dirstamp
 am_knock_OBJECTS = src/knock.$(OBJEXT)
@@ -106,41 +116,7 @@ knock_LDADD = $(LDADD)
 am_knockd_OBJECTS = src/knockd.$(OBJEXT) src/list.$(OBJEXT)
 knockd_OBJECTS = $(am_knockd_OBJECTS)
 knockd_LDADD = $(LDADD)
-AM_V_P = $(am__v_P_@AM_V@)
-am__v_P_ = $(am__v_P_@AM_DEFAULT_V@)
-am__v_P_0 = false
-am__v_P_1 = :
-AM_V_GEN = $(am__v_GEN_@AM_V@)
-am__v_GEN_ = $(am__v_GEN_@AM_DEFAULT_V@)
-am__v_GEN_0 = @echo "  GEN     " $@;
-am__v_GEN_1 = 
-AM_V_at = $(am__v_at_@AM_V@)
-am__v_at_ = $(am__v_at_@AM_DEFAULT_V@)
-am__v_at_0 = @
-am__v_at_1 = 
-DEFAULT_INCLUDES = -I.@am__isrc@
-depcomp = $(SHELL) $(top_srcdir)/depcomp
-am__depfiles_maybe = depfiles
-am__mv = mv -f
-COMPILE = $(CC) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) $(AM_CPPFLAGS) \
-	$(CPPFLAGS) $(AM_CFLAGS) $(CFLAGS)
-AM_V_CC = $(am__v_CC_@AM_V@)
-am__v_CC_ = $(am__v_CC_@AM_DEFAULT_V@)
-am__v_CC_0 = @echo "  CC      " $@;
-am__v_CC_1 = 
-CCLD = $(CC)
-LINK = $(CCLD) $(AM_CFLAGS) $(CFLAGS) $(AM_LDFLAGS) $(LDFLAGS) -o $@
-AM_V_CCLD = $(am__v_CCLD_@AM_V@)
-am__v_CCLD_ = $(am__v_CCLD_@AM_DEFAULT_V@)
-am__v_CCLD_0 = @echo "  CCLD    " $@;
-am__v_CCLD_1 = 
-SOURCES = $(knock_SOURCES) $(knockd_SOURCES)
-DIST_SOURCES = $(knock_SOURCES) $(knockd_SOURCES)
-am__can_run_installinfo = \
-  case $$AM_UPDATE_INFO_DIR in \
-    n|no|NO) false;; \
-    *) (install-info --version) >/dev/null 2>&1;; \
-  esac
+am__dist_sbin_SCRIPTS_DIST = src/knock_helper_ipt.sh
 am__vpath_adj_setup = srcdirstrip=`echo "$(srcdir)" | sed 's|.|.|g'`;
 am__vpath_adj = case $$p in \
    $(srcdir)/*) f=`echo "$$p" | sed "s|^$$srcdirstrip/||"`;; \
@@ -168,12 +144,50 @@ am__uninstall_files_from_dir = { \
    || { echo " ( cd '$$dir' && rm -f" $$files ")"; \
         $(am__cd) "$$dir" && rm -f $$files; }; \
  }
+SCRIPTS = $(dist_sbin_SCRIPTS)
+AM_V_P = $(am__v_P_@AM_V@)
+am__v_P_ = $(am__v_P_@AM_DEFAULT_V@)
+am__v_P_0 = false
+am__v_P_1 = :
+AM_V_GEN = $(am__v_GEN_@AM_V@)
+am__v_GEN_ = $(am__v_GEN_@AM_DEFAULT_V@)
+am__v_GEN_0 = @echo "  GEN     " $@;
+am__v_GEN_1 = 
+AM_V_at = $(am__v_at_@AM_V@)
+am__v_at_ = $(am__v_at_@AM_DEFAULT_V@)
+am__v_at_0 = @
+am__v_at_1 = 
+DEFAULT_INCLUDES = -I.@am__isrc@
+depcomp = $(SHELL) $(top_srcdir)/depcomp
+am__maybe_remake_depfiles = depfiles
+am__depfiles_remade = src/$(DEPDIR)/knock.Po src/$(DEPDIR)/knockd.Po \
+	src/$(DEPDIR)/list.Po
+am__mv = mv -f
+COMPILE = $(CC) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) $(AM_CPPFLAGS) \
+	$(CPPFLAGS) $(AM_CFLAGS) $(CFLAGS)
+AM_V_CC = $(am__v_CC_@AM_V@)
+am__v_CC_ = $(am__v_CC_@AM_DEFAULT_V@)
+am__v_CC_0 = @echo "  CC      " $@;
+am__v_CC_1 = 
+CCLD = $(CC)
+LINK = $(CCLD) $(AM_CFLAGS) $(CFLAGS) $(AM_LDFLAGS) $(LDFLAGS) -o $@
+AM_V_CCLD = $(am__v_CCLD_@AM_V@)
+am__v_CCLD_ = $(am__v_CCLD_@AM_DEFAULT_V@)
+am__v_CCLD_0 = @echo "  CCLD    " $@;
+am__v_CCLD_1 = 
+SOURCES = $(knock_SOURCES) $(knockd_SOURCES)
+DIST_SOURCES = $(knock_SOURCES) $(knockd_SOURCES)
+am__can_run_installinfo = \
+  case $$AM_UPDATE_INFO_DIR in \
+    n|no|NO) false;; \
+    *) (install-info --version) >/dev/null 2>&1;; \
+  esac
 man1dir = $(mandir)/man1
 NROFF = nroff
 MANS = $(man_MANS)
 DATA = $(dist_doc_DATA) $(sysconf_DATA)
-am__tagged_files = $(HEADERS) $(SOURCES) $(TAGS_FILES) \
-	$(LISP)config.h.in
+am__tagged_files = $(HEADERS) $(SOURCES) $(TAGS_FILES) $(LISP) \
+	config.h.in
 # Read a list of newline-separated strings from the standard input,
 # and print each of them once, without duplicates.  Input order is
 # *not* preserved.
@@ -194,6 +208,8 @@ ETAGS = etags
 CTAGS = ctags
 CSCOPE = cscope
 AM_RECURSIVE_TARGETS = cscope
+am__DIST_COMMON = $(srcdir)/Makefile.in $(srcdir)/config.h.in COPYING \
+	ChangeLog TODO compile depcomp install-sh missing
 DISTFILES = $(DIST_COMMON) $(DIST_SOURCES) $(TEXINFOS) $(EXTRA_DIST)
 distdir = $(PACKAGE)-$(VERSION)
 top_distdir = $(distdir)
@@ -207,6 +223,8 @@ am__post_remove_distdir = $(am__remove_distdir)
 GZIP_ENV = --best
 DIST_ARCHIVES = $(distdir).tar.xz
 DIST_TARGETS = dist-xz
+# Exists only to be overridden by the user if desired.
+AM_DISTCHECK_DVI_TARGET = dvi
 distuninstallcheck_listfiles = find . -type f -print
 am__distuninstallcheck_listfiles = $(distuninstallcheck_listfiles) \
  | sed 's|^\./|$(prefix)/|' | grep -v '$(infodir)/dir$$'
@@ -221,7 +239,6 @@ AWK = @AWK@
 CC = @CC@
 CCDEPMODE = @CCDEPMODE@
 CFLAGS = @CFLAGS@
-CPP = @CPP@
 CPPFLAGS = @CPPFLAGS@
 CYGPATH_W = @CYGPATH_W@
 DEFS = @DEFS@
@@ -229,9 +246,7 @@ DEPDIR = @DEPDIR@
 ECHO_C = @ECHO_C@
 ECHO_N = @ECHO_N@
 ECHO_T = @ECHO_T@
-EGREP = @EGREP@
 EXEEXT = @EXEEXT@
-GREP = @GREP@
 INSTALL = @INSTALL@
 INSTALL_DATA = @INSTALL_DATA@
 INSTALL_PROGRAM = @INSTALL_PROGRAM@
@@ -290,6 +305,7 @@ pdfdir = @pdfdir@
 prefix = @prefix@
 program_transform_name = @program_transform_name@
 psdir = @psdir@
+runstatedir = @runstatedir@
 sbindir = @sbindir@
 sharedstatedir = @sharedstatedir@
 srcdir = @srcdir@
@@ -298,14 +314,16 @@ target_alias = @target_alias@
 top_build_prefix = @top_build_prefix@
 top_builddir = @top_builddir@
 top_srcdir = @top_srcdir@
-AM_CPPFLAGS = -D_BSD_SOURCE
-AM_CFLAGS = -g -Wall -pedantic -fno-exceptions
+AM_CPPFLAGS = -D_DEFAULT_SOURCE
+AM_CFLAGS = -g -Wall -pedantic -fno-exceptions -D_BSD_SOURCE
 man_MANS = doc/knock.1 $(am__append_1)
+@BUILD_KNOCKD_TRUE@dist_sbin_SCRIPTS = src/knock_helper_ipt.sh
@BUILD_KNOCKD_TRUE@sysconf_DATA = knockd.conf
 dist_doc_DATA = README.md TODO ChangeLog COPYING
 knock_SOURCES = src/knock.c
-knockd_SOURCES = src/knockd.c src/list.c src/list.h
+knockd_SOURCES = src/knockd.c src/list.c src/list.h src/knock_helper_ipt.sh
 EXTRA_DIST = doc/knock.1 doc/knock.1.in doc/knockd.1 doc/knockd.1.in knockd.conf
+CLEANFILES = $(man_MANS)
 all: config.h
 	$(MAKE) $(AM_MAKEFLAGS) all-am

@@ -326,15 +344,14 @@ $(srcdir)/Makefile.in:  $(srcdir)/Makefile.am  $(am__configure_deps)
 	echo ' cd $(top_srcdir) && $(AUTOMAKE) --foreign Makefile'; \
 	$(am__cd) $(top_srcdir) && \
 	  $(AUTOMAKE) --foreign Makefile
-.PRECIOUS: Makefile
 Makefile: $(srcdir)/Makefile.in $(top_builddir)/config.status
 	@case '$?' in \
 	  *config.status*) \
 	    echo ' $(SHELL) ./config.status'; \
 	    $(SHELL) ./config.status;; \
 	  *) \
-	    echo ' cd $(top_builddir) && $(SHELL) ./config.status $@ $(am__depfiles_maybe)'; \
-	    cd $(top_builddir) && $(SHELL) ./config.status $@ $(am__depfiles_maybe);; \
+	    echo ' cd $(top_builddir) && $(SHELL) ./config.status $@ $(am__maybe_remake_depfiles)'; \
+	    cd $(top_builddir) && $(SHELL) ./config.status $@ $(am__maybe_remake_depfiles);; \
 	esac;

 $(top_builddir)/config.status: $(top_srcdir)/configure $(CONFIG_STATUS_DEPENDENCIES)
@@ -462,6 +479,41 @@ src/list.$(OBJEXT): src/$(am__dirstamp) src/$(DEPDIR)/$(am__dirstamp)
 knockd$(EXEEXT): $(knockd_OBJECTS) $(knockd_DEPENDENCIES) $(EXTRA_knockd_DEPENDENCIES) 
 	@rm -f knockd$(EXEEXT)
 	$(AM_V_CCLD)$(LINK) $(knockd_OBJECTS) $(knockd_LDADD) $(LIBS)
+install-dist_sbinSCRIPTS: $(dist_sbin_SCRIPTS)
+	@$(NORMAL_INSTALL)
+	@list='$(dist_sbin_SCRIPTS)'; test -n "$(sbindir)" || list=; \
+	if test -n "$$list"; then \
+	  echo " $(MKDIR_P) '$(DESTDIR)$(sbindir)'"; \
+	  $(MKDIR_P) "$(DESTDIR)$(sbindir)" || exit 1; \
+	fi; \
+	for p in $$list; do \
+	  if test -f "$$p"; then d=; else d="$(srcdir)/"; fi; \
+	  if test -f "$$d$$p"; then echo "$$d$$p"; echo "$$p"; else :; fi; \
+	done | \
+	sed -e 'p;s,.*/,,;n' \
+	    -e 'h;s|.*|.|' \
+	    -e 'p;x;s,.*/,,;$(transform)' | sed 'N;N;N;s,\n, ,g' | \
+	$(AWK) 'BEGIN { files["."] = ""; dirs["."] = 1; } \
+	  { d=$$3; if (dirs[d] != 1) { print "d", d; dirs[d] = 1 } \
+	    if ($$2 == $$4) { files[d] = files[d] " " $$1; \
+	      if (++n[d] == $(am__install_max)) { \
+		print "f", d, files[d]; n[d] = 0; files[d] = "" } } \
+	    else { print "f", d "/" $$4, $$1 } } \
+	  END { for (d in files) print "f", d, files[d] }' | \
+	while read type dir files; do \
+	     if test "$$dir" = .; then dir=; else dir=/$$dir; fi; \
+	     test -z "$$files" || { \
+	       echo " $(INSTALL_SCRIPT) $$files '$(DESTDIR)$(sbindir)$$dir'"; \
+	       $(INSTALL_SCRIPT) $$files "$(DESTDIR)$(sbindir)$$dir" || exit $$?; \
+	     } \
+	; done
+
+uninstall-dist_sbinSCRIPTS:
+	@$(NORMAL_UNINSTALL)
+	@list='$(dist_sbin_SCRIPTS)'; test -n "$(sbindir)" || exit 0; \
+	files=`for p in $$list; do echo "$$p"; done | \
+	       sed -e 's,.*/,,;$(transform)'`; \
+	dir='$(DESTDIR)$(sbindir)'; $(am__uninstall_files_from_dir)

 mostlyclean-compile:
 	-rm -f *.$(OBJEXT)
@@ -470,9 +522,15 @@ mostlyclean-compile:
 distclean-compile:
 	-rm -f *.tab.c

-@AMDEP_TRUE@@am__include@ @am__quote@src/$(DEPDIR)/knock.Po@am__quote@
-@AMDEP_TRUE@@am__include@ @am__quote@src/$(DEPDIR)/knockd.Po@am__quote@
-@AMDEP_TRUE@@am__include@ @am__quote@src/$(DEPDIR)/list.Po@am__quote@
+@AMDEP_TRUE@@am__include@ @am__quote@src/$(DEPDIR)/knock.Po@am__quote@ # am--include-marker
+@AMDEP_TRUE@@am__include@ @am__quote@src/$(DEPDIR)/knockd.Po@am__quote@ # am--include-marker
+@AMDEP_TRUE@@am__include@ @am__quote@src/$(DEPDIR)/list.Po@am__quote@ # am--include-marker
+
+$(am__depfiles_remade):
+	@$(MKDIR_P) $(@D)
+	@echo '# dummy' >$@-t && $(am__mv) $@-t $@
+
+am--depfiles: $(am__depfiles_remade)

 .c.o:
@am__fastdepCC_TRUE@	$(AM_V_CC)depbase=`echo $@ | sed 's|[^/]*$$|$(DEPDIR)/&|;s|\.o$$||'`;\
@@ -634,7 +692,10 @@ distclean-tags:
 	-rm -f TAGS ID GTAGS GRTAGS GSYMS GPATH tags
 	-rm -f cscope.out cscope.in.out cscope.po.out cscope.files

-distdir: $(DISTFILES)
+distdir: $(BUILT_SOURCES)
+	$(MAKE) $(AM_MAKEFLAGS) distdir-am
+
+distdir-am: $(DISTFILES)
 	$(am__remove_distdir)
 	test -d "$(distdir)" || mkdir "$(distdir)"
 	@srcdirstrip=`echo "$(srcdir)" | sed 's/[].[^$$\\*]/\\\\&/g'`; \
@@ -674,7 +735,7 @@ distdir: $(DISTFILES)
 	  ! -type d ! -perm -444 -exec $(install_sh) -c -m a+r {} {} \; \
 	|| chmod -R a+r "$(distdir)"
 dist-gzip: distdir
-	tardir=$(distdir) && $(am__tar) | GZIP=$(GZIP_ENV) gzip -c >$(distdir).tar.gz
+	tardir=$(distdir) && $(am__tar) | eval GZIP= gzip $(GZIP_ENV) -c >$(distdir).tar.gz
 	$(am__post_remove_distdir)

 dist-bzip2: distdir
@@ -688,18 +749,22 @@ dist-xz: distdir
 	tardir=$(distdir) && $(am__tar) | XZ_OPT=$${XZ_OPT--e} xz -c >$(distdir).tar.xz
 	$(am__post_remove_distdir)

+dist-zstd: distdir
+	tardir=$(distdir) && $(am__tar) | zstd -c $${ZSTD_CLEVEL-$${ZSTD_OPT--19}} >$(distdir).tar.zst
+	$(am__post_remove_distdir)
+
 dist-tarZ: distdir
-	@echo WARNING: "Support for shar distribution archives is" \
-	               "deprecated." >&2
+	@echo WARNING: "Support for distribution archives compressed with" \
+		       "legacy program 'compress' is deprecated." >&2
 	@echo WARNING: "It will be removed altogether in Automake 2.0" >&2
 	tardir=$(distdir) && $(am__tar) | compress -c >$(distdir).tar.Z
 	$(am__post_remove_distdir)

 dist-shar: distdir
-	@echo WARNING: "Support for distribution archives compressed with" \
-		       "legacy program 'compress' is deprecated." >&2
+	@echo WARNING: "Support for shar distribution archives is" \
+	               "deprecated." >&2
 	@echo WARNING: "It will be removed altogether in Automake 2.0" >&2
-	shar $(distdir) | GZIP=$(GZIP_ENV) gzip -c >$(distdir).shar.gz
+	shar $(distdir) | eval GZIP= gzip $(GZIP_ENV) -c >$(distdir).shar.gz
 	$(am__post_remove_distdir)

 dist-zip: distdir
@@ -717,7 +782,7 @@ dist dist-all:
 distcheck: dist
 	case '$(DIST_ARCHIVES)' in \
 	*.tar.gz*) \
-	  GZIP=$(GZIP_ENV) gzip -dc $(distdir).tar.gz | $(am__untar) ;;\
+	  eval GZIP= gzip $(GZIP_ENV) -dc $(distdir).tar.gz | $(am__untar) ;;\
 	*.tar.bz2*) \
 	  bzip2 -dc $(distdir).tar.bz2 | $(am__untar) ;;\
 	*.tar.lz*) \
@@ -727,25 +792,27 @@ distcheck: dist
 	*.tar.Z*) \
 	  uncompress -c $(distdir).tar.Z | $(am__untar) ;;\
 	*.shar.gz*) \
-	  GZIP=$(GZIP_ENV) gzip -dc $(distdir).shar.gz | unshar ;;\
+	  eval GZIP= gzip $(GZIP_ENV) -dc $(distdir).shar.gz | unshar ;;\
 	*.zip*) \
 	  unzip $(distdir).zip ;;\
+	*.tar.zst*) \
+	  zstd -dc $(distdir).tar.zst | $(am__untar) ;;\
 	esac
 	chmod -R a-w $(distdir)
 	chmod u+w $(distdir)
-	mkdir $(distdir)/_build $(distdir)/_inst
+	mkdir $(distdir)/_build $(distdir)/_build/sub $(distdir)/_inst
 	chmod a-w $(distdir)
 	test -d $(distdir)/_build || exit 0; \
 	dc_install_base=`$(am__cd) $(distdir)/_inst && pwd | sed -e 's,^[^:\\/]:[\\/],/,'` \
 	  && dc_destdir="$${TMPDIR-/tmp}/am-dc-$$$$/" \
 	  && am__cwd=`pwd` \
-	  && $(am__cd) $(distdir)/_build \
-	  && ../configure \
+	  && $(am__cd) $(distdir)/_build/sub \
+	  && ../../configure \
 	    $(AM_DISTCHECK_CONFIGURE_FLAGS) \
 	    $(DISTCHECK_CONFIGURE_FLAGS) \
-	    --srcdir=.. --prefix="$$dc_install_base" \
+	    --srcdir=../.. --prefix="$$dc_install_base" \
 	  && $(MAKE) $(AM_MAKEFLAGS) \
-	  && $(MAKE) $(AM_MAKEFLAGS) dvi \
+	  && $(MAKE) $(AM_MAKEFLAGS) $(AM_DISTCHECK_DVI_TARGET) \
 	  && $(MAKE) $(AM_MAKEFLAGS) check \
 	  && $(MAKE) $(AM_MAKEFLAGS) install \
 	  && $(MAKE) $(AM_MAKEFLAGS) installcheck \
@@ -798,9 +865,9 @@ distcleancheck: distclean
 	       exit 1; } >&2
 check-am: all-am
 check: check-am
-all-am: Makefile $(PROGRAMS) $(MANS) $(DATA) config.h
+all-am: Makefile $(PROGRAMS) $(SCRIPTS) $(MANS) $(DATA) config.h
 installdirs:
-	for dir in "$(DESTDIR)$(bindir)" "$(DESTDIR)$(sbindir)" "$(DESTDIR)$(man1dir)" "$(DESTDIR)$(docdir)" "$(DESTDIR)$(sysconfdir)"; do \
+	for dir in "$(DESTDIR)$(bindir)" "$(DESTDIR)$(sbindir)" "$(DESTDIR)$(sbindir)" "$(DESTDIR)$(man1dir)" "$(DESTDIR)$(docdir)" "$(DESTDIR)$(sysconfdir)"; do \
 	  test -z "$$dir" || $(MKDIR_P) "$$dir"; \
 	done
 install: install-am
@@ -825,6 +892,7 @@ install-strip:
 mostlyclean-generic:

 clean-generic:
+	-test -z "$(CLEANFILES)" || rm -f $(CLEANFILES)

 distclean-generic:
 	-test -z "$(CONFIG_CLEAN_FILES)" || rm -f $(CONFIG_CLEAN_FILES)
@@ -842,7 +910,9 @@ clean-am: clean-binPROGRAMS clean-generic clean-sbinPROGRAMS \

 distclean: distclean-am
 	-rm -f $(am__CONFIG_DISTCLEAN_FILES)
-	-rm -rf src/$(DEPDIR)
+		-rm -f src/$(DEPDIR)/knock.Po
+	-rm -f src/$(DEPDIR)/knockd.Po
+	-rm -f src/$(DEPDIR)/list.Po
 	-rm -f Makefile
 distclean-am: clean-am distclean-compile distclean-generic \
 	distclean-hdr distclean-tags
@@ -865,8 +935,8 @@ install-dvi: install-dvi-am

 install-dvi-am:

-install-exec-am: install-binPROGRAMS install-sbinPROGRAMS \
-	install-sysconfDATA
+install-exec-am: install-binPROGRAMS install-dist_sbinSCRIPTS \
+	install-sbinPROGRAMS install-sysconfDATA

 install-html: install-html-am

@@ -891,7 +961,9 @@ installcheck-am:
 maintainer-clean: maintainer-clean-am
 	-rm -f $(am__CONFIG_DISTCLEAN_FILES)
 	-rm -rf $(top_srcdir)/autom4te.cache
-	-rm -rf src/$(DEPDIR)
+		-rm -f src/$(DEPDIR)/knock.Po
+	-rm -f src/$(DEPDIR)/knockd.Po
+	-rm -f src/$(DEPDIR)/list.Po
 	-rm -f Makefile
 maintainer-clean-am: distclean-am maintainer-clean-generic

@@ -908,21 +980,23 @@ ps: ps-am
 ps-am:

 uninstall-am: uninstall-binPROGRAMS uninstall-dist_docDATA \
-	uninstall-man uninstall-sbinPROGRAMS uninstall-sysconfDATA
+	uninstall-dist_sbinSCRIPTS uninstall-man \
+	uninstall-sbinPROGRAMS uninstall-sysconfDATA

 uninstall-man: uninstall-man1

 .MAKE: all install-am install-strip

-.PHONY: CTAGS GTAGS TAGS all all-am am--refresh check check-am clean \
-	clean-binPROGRAMS clean-cscope clean-generic \
+.PHONY: CTAGS GTAGS TAGS all all-am am--depfiles am--refresh check \
+	check-am clean clean-binPROGRAMS clean-cscope clean-generic \
 	clean-sbinPROGRAMS cscope cscopelist-am ctags ctags-am dist \
 	dist-all dist-bzip2 dist-gzip dist-lzip dist-shar dist-tarZ \
-	dist-xz dist-zip distcheck distclean distclean-compile \
-	distclean-generic distclean-hdr distclean-tags distcleancheck \
-	distdir distuninstallcheck dvi dvi-am html html-am info \
-	info-am install install-am install-binPROGRAMS install-data \
-	install-data-am install-dist_docDATA install-dvi \
+	dist-xz dist-zip dist-zstd distcheck distclean \
+	distclean-compile distclean-generic distclean-hdr \
+	distclean-tags distcleancheck distdir distuninstallcheck dvi \
+	dvi-am html html-am info info-am install install-am \
+	install-binPROGRAMS install-data install-data-am \
+	install-dist_docDATA install-dist_sbinSCRIPTS install-dvi \
 	install-dvi-am install-exec install-exec-am install-html \
 	install-html-am install-info install-info-am install-man \
 	install-man1 install-pdf install-pdf-am install-ps \
@@ -931,8 +1005,11 @@ uninstall-man: uninstall-man1
 	maintainer-clean maintainer-clean-generic mostlyclean \
 	mostlyclean-compile mostlyclean-generic pdf pdf-am ps ps-am \
 	tags tags-am uninstall uninstall-am uninstall-binPROGRAMS \
-	uninstall-dist_docDATA uninstall-man uninstall-man1 \
-	uninstall-sbinPROGRAMS uninstall-sysconfDATA
+	uninstall-dist_docDATA uninstall-dist_sbinSCRIPTS \
+	uninstall-man uninstall-man1 uninstall-sbinPROGRAMS \
+	uninstall-sysconfDATA
+
+.PRECIOUS: Makefile


 %.1: %.1.in
--- a/README.md
+++ b/README.md
@@ -41,12 +41,10 @@ can only be accessed after a successful knock sequence.
 ### KNOCKING CLIENTS

 The accompanying knock client is very basic.  If you want to do more advanced
-knocks (eg, setting specific tcp flags) then you should take look at hping,
-sendip or packit.
+knocks (eg, setting specific tcp flags) then you should take look at more
+powerful clients.

-  - [hping](http://freshmeat.net/projects/hping/)
  - [sendip](http://freshmeat.net/projects/sendip/)
-  - [packit](http://freshmeat.net/projects/packit/)


 ### OTHER IMPLEMENTATIONS  
--- a/aclocal.m4
+++ b/aclocal.m4
@@ -1,6 +1,6 @@
-# generated automatically by aclocal 1.14.1 -*- Autoconf -*-
+# generated automatically by aclocal 1.16.3 -*- Autoconf -*-

-# Copyright (C) 1996-2013 Free Software Foundation, Inc.
+# Copyright (C) 1996-2020 Free Software Foundation, Inc.

 # This file is free software; the Free Software Foundation
 # gives unlimited permission to copy and/or distribute it,
@@ -14,13 +14,13 @@
 m4_ifndef([AC_CONFIG_MACRO_DIRS], [m4_defun([_AM_CONFIG_MACRO_DIRS], [])m4_defun([AC_CONFIG_MACRO_DIRS], [_AM_CONFIG_MACRO_DIRS($@)])])
 m4_ifndef([AC_AUTOCONF_VERSION],
  [m4_copy([m4_PACKAGE_VERSION], [AC_AUTOCONF_VERSION])])dnl
-m4_if(m4_defn([AC_AUTOCONF_VERSION]), [2.69],,
-[m4_warning([this file was generated for autoconf 2.69.
+m4_if(m4_defn([AC_AUTOCONF_VERSION]), [2.71],,
+[m4_warning([this file was generated for autoconf 2.71.
 You have another version of autoconf.  It may work, but is not guaranteed to.
 If you have problems, you may need to regenerate the build system entirely.
 To do so, use the procedure documented by the package, typically 'autoreconf'.])])

-# Copyright (C) 2002-2013 Free Software Foundation, Inc.
+# Copyright (C) 2002-2020 Free Software Foundation, Inc.
 #
 # This file is free software; the Free Software Foundation
 # gives unlimited permission to copy and/or distribute it,
@@ -32,10 +32,10 @@ To do so, use the procedure documented by the package, typically 'autoreconf'.])
 # generated from the m4 files accompanying Automake X.Y.
 # (This private macro should not be called outside this file.)
 AC_DEFUN([AM_AUTOMAKE_VERSION],
-[am__api_version='1.14'
+[am__api_version='1.16'
 dnl Some users find AM_AUTOMAKE_VERSION and mistake it for a way to
 dnl require some minimum version.  Point them to the right macro.
-m4_if([$1], [1.14.1], [],
+m4_if([$1], [1.16.3], [],
      [AC_FATAL([Do not call $0, use AM_INIT_AUTOMAKE([$1]).])])dnl
 ])

@@ -51,14 +51,14 @@ m4_define([_AM_AUTOCONF_VERSION], [])
 # Call AM_AUTOMAKE_VERSION and AM_AUTOMAKE_VERSION so they can be traced.
 # This function is AC_REQUIREd by AM_INIT_AUTOMAKE.
 AC_DEFUN([AM_SET_CURRENT_AUTOMAKE_VERSION],
-[AM_AUTOMAKE_VERSION([1.14.1])dnl
+[AM_AUTOMAKE_VERSION([1.16.3])dnl
 m4_ifndef([AC_AUTOCONF_VERSION],
  [m4_copy([m4_PACKAGE_VERSION], [AC_AUTOCONF_VERSION])])dnl
 _AM_AUTOCONF_VERSION(m4_defn([AC_AUTOCONF_VERSION]))])

 # AM_AUX_DIR_EXPAND                                         -*- Autoconf -*-

-# Copyright (C) 2001-2013 Free Software Foundation, Inc.
+# Copyright (C) 2001-2020 Free Software Foundation, Inc.
 #
 # This file is free software; the Free Software Foundation
 # gives unlimited permission to copy and/or distribute it,
@@ -103,15 +103,14 @@ _AM_AUTOCONF_VERSION(m4_defn([AC_AUTOCONF_VERSION]))])
 # configured tree to be moved without reconfiguration.

 AC_DEFUN([AM_AUX_DIR_EXPAND],
-[dnl Rely on autoconf to set up CDPATH properly.
-AC_PREREQ([2.50])dnl
-# expand $ac_aux_dir to an absolute path
-am_aux_dir=`cd $ac_aux_dir && pwd`
+[AC_REQUIRE([AC_CONFIG_AUX_DIR_DEFAULT])dnl
+# Expand $ac_aux_dir to an absolute path.
+am_aux_dir=`cd "$ac_aux_dir" && pwd`
 ])

 # AM_CONDITIONAL                                            -*- Autoconf -*-

-# Copyright (C) 1997-2013 Free Software Foundation, Inc.
+# Copyright (C) 1997-2020 Free Software Foundation, Inc.
 #
 # This file is free software; the Free Software Foundation
 # gives unlimited permission to copy and/or distribute it,
@@ -142,7 +141,7 @@ AC_CONFIG_COMMANDS_PRE(
 Usually this means the macro was only invoked conditionally.]])
 fi])])

-# Copyright (C) 1999-2013 Free Software Foundation, Inc.
+# Copyright (C) 1999-2020 Free Software Foundation, Inc.
 #
 # This file is free software; the Free Software Foundation
 # gives unlimited permission to copy and/or distribute it,
@@ -333,13 +332,12 @@ _AM_SUBST_NOTMAKE([am__nodep])dnl

 # Generate code to set up dependency tracking.              -*- Autoconf -*-

-# Copyright (C) 1999-2013 Free Software Foundation, Inc.
+# Copyright (C) 1999-2020 Free Software Foundation, Inc.
 #
 # This file is free software; the Free Software Foundation
 # gives unlimited permission to copy and/or distribute it,
 # with or without modifications, as long as this notice is preserved.

-
 # _AM_OUTPUT_DEPENDENCY_COMMANDS
 # ------------------------------
 AC_DEFUN([_AM_OUTPUT_DEPENDENCY_COMMANDS],
@@ -347,49 +345,43 @@ AC_DEFUN([_AM_OUTPUT_DEPENDENCY_COMMANDS],
  # Older Autoconf quotes --file arguments for eval, but not when files
  # are listed without --file.  Let's play safe and only enable the eval
  # if we detect the quoting.
-  case $CONFIG_FILES in
-  *\'*) eval set x "$CONFIG_FILES" ;;
-  *)   set x $CONFIG_FILES ;;
-  esac
+  # TODO: see whether this extra hack can be removed once we start
+  # requiring Autoconf 2.70 or later.
+  AS_CASE([$CONFIG_FILES],
+          [*\'*], [eval set x "$CONFIG_FILES"],
+          [*], [set x $CONFIG_FILES])
  shift
-  for mf
+  # Used to flag and report bootstrapping failures.
+  am_rc=0
+  for am_mf
  do
    # Strip MF so we end up with the name of the file.
-    mf=`echo "$mf" | sed -e 's/:.*$//'`
-    # Check whether this is an Automake generated Makefile or not.
-    # We used to match only the files named 'Makefile.in', but
-    # some people rename them; so instead we look at the file content.
-    # Grep'ing the first line is not enough: some people post-process
-    # each Makefile.in and add a new line on top of each file to say so.
-    # Grep'ing the whole file is not good either: AIX grep has a line
+    am_mf=`AS_ECHO(["$am_mf"]) | sed -e 's/:.*$//'`
+    # Check whether this is an Automake generated Makefile which includes
+    # dependency-tracking related rules and includes.
+    # Grep'ing the whole file directly is not great: AIX grep has a line
    # limit of 2048, but all sed's we know have understand at least 4000.
-    if sed -n 's,^#.*generated by automake.*,X,p' "$mf" | grep X >/dev/null 2>&1; then
-      dirpart=`AS_DIRNAME("$mf")`
-    else
-      continue
+    sed -n 's,^am--depfiles:.*,X,p' "$am_mf" | grep X >/dev/null 2>&1 \
+      || continue
+    am_dirpart=`AS_DIRNAME(["$am_mf"])`
+    am_filepart=`AS_BASENAME(["$am_mf"])`
+    AM_RUN_LOG([cd "$am_dirpart" \
+      && sed -e '/# am--include-marker/d' "$am_filepart" \
+        | $MAKE -f - am--depfiles]) || am_rc=$?
+  done
+  if test $am_rc -ne 0; then
+    AC_MSG_FAILURE([Something went wrong bootstrapping makefile fragments
+    for automatic dependency tracking.  If GNU make was not used, consider
+    re-running the configure script with MAKE="gmake" (or whatever is
+    necessary).  You can also try re-running configure with the
+    '--disable-dependency-tracking' option to at least be able to build
+    the package (albeit without support for automatic dependency tracking).])
  fi
-    # Extract the definition of DEPDIR, am__include, and am__quote
-    # from the Makefile without running 'make'.
-    DEPDIR=`sed -n 's/^DEPDIR = //p' < "$mf"`
-    test -z "$DEPDIR" && continue
-    am__include=`sed -n 's/^am__include = //p' < "$mf"`
-    test -z "$am__include" && continue
-    am__quote=`sed -n 's/^am__quote = //p' < "$mf"`
-    # Find all dependency output files, they are included files with
-    # $(DEPDIR) in their names.  We invoke sed twice because it is the
-    # simplest approach to changing $(DEPDIR) to its actual value in the
-    # expansion.
-    for file in `sed -n "
-      s/^$am__include $am__quote\(.*(DEPDIR).*\)$am__quote"'$/\1/p' <"$mf" | \
-	 sed -e 's/\$(DEPDIR)/'"$DEPDIR"'/g'`; do
-      # Make sure the directory exists.
-      test -f "$dirpart/$file" && continue
-      fdir=`AS_DIRNAME(["$file"])`
-      AS_MKDIR_P([$dirpart/$fdir])
-      # echo "creating $dirpart/$file"
-      echo '# dummy' > "$dirpart/$file"
-    done
-  done
+  AS_UNSET([am_dirpart])
+  AS_UNSET([am_filepart])
+  AS_UNSET([am_mf])
+  AS_UNSET([am_rc])
+  rm -f conftest-deps.mk
 }
 ])# _AM_OUTPUT_DEPENDENCY_COMMANDS

@@ -398,18 +390,17 @@ AC_DEFUN([_AM_OUTPUT_DEPENDENCY_COMMANDS],
 # -----------------------------
 # This macro should only be invoked once -- use via AC_REQUIRE.
 #
-# This code is only required when automatic dependency tracking
-# is enabled.  FIXME.  This creates each '.P' file that we will
-# need in order to bootstrap the dependency handling code.
+# This code is only required when automatic dependency tracking is enabled.
+# This creates each '.Po' and '.Plo' makefile fragment that we'll need in
+# order to bootstrap the dependency handling code.
 AC_DEFUN([AM_OUTPUT_DEPENDENCY_COMMANDS],
 [AC_CONFIG_COMMANDS([depfiles],
     [test x"$AMDEP_TRUE" != x"" || _AM_OUTPUT_DEPENDENCY_COMMANDS],
-     [AMDEP_TRUE="$AMDEP_TRUE" ac_aux_dir="$ac_aux_dir"])
-])
+     [AMDEP_TRUE="$AMDEP_TRUE" MAKE="${MAKE-make}"])])

 # Do all the work for Automake.                             -*- Autoconf -*-

-# Copyright (C) 1996-2013 Free Software Foundation, Inc.
+# Copyright (C) 1996-2020 Free Software Foundation, Inc.
 #
 # This file is free software; the Free Software Foundation
 # gives unlimited permission to copy and/or distribute it,
@@ -496,11 +487,11 @@ AC_REQUIRE([AM_PROG_INSTALL_STRIP])dnl
 AC_REQUIRE([AC_PROG_MKDIR_P])dnl
 # For better backward compatibility.  To be removed once Automake 1.9.x
 # dies out for good.  For more background, see:
-# <http://lists.gnu.org/archive/html/automake/2012-07/msg00001.html>
-# <http://lists.gnu.org/archive/html/automake/2012-07/msg00014.html>
+# <https://lists.gnu.org/archive/html/automake/2012-07/msg00001.html>
+# <https://lists.gnu.org/archive/html/automake/2012-07/msg00014.html>
 AC_SUBST([mkdir_p], ['$(MKDIR_P)'])
-# We need awk for the "check" target.  The system "awk" is bad on
-# some platforms.
+# We need awk for the "check" target (and possibly the TAP driver).  The
+# system "awk" is bad on some platforms.
 AC_REQUIRE([AC_PROG_AWK])dnl
 AC_REQUIRE([AC_PROG_MAKE_SET])dnl
 AC_REQUIRE([AM_SET_LEADING_DOT])dnl
@@ -564,7 +555,7 @@ END
 Aborting the configuration process, to ensure you take notice of the issue.

 You can download and install GNU coreutils to get an 'rm' implementation
-that behaves properly: <http://www.gnu.org/software/coreutils/>.
+that behaves properly: <https://www.gnu.org/software/coreutils/>.

 If you want to complete the configuration process using your problematic
 'rm' anyway, export the environment variable ACCEPT_INFERIOR_RM_PROGRAM
@@ -573,7 +564,11 @@ to "yes", and re-run configure.
 END
    AC_MSG_ERROR([Your 'rm' program is bad, sorry.])
  fi
-fi])
+fi
+dnl The trailing newline in this macro's definition is deliberate, for
+dnl backward compatibility and to allow trailing 'dnl'-style comments
+dnl after the AM_INIT_AUTOMAKE invocation. See automake bug#16841.
+])

 dnl Hook into '_AC_COMPILER_EXEEXT' early to learn its expansion.  Do not
 dnl add the conditional right here, as _AC_COMPILER_EXEEXT may be further
@@ -602,7 +597,7 @@ for _am_header in $config_headers :; do
 done
 echo "timestamp for $_am_arg" >`AS_DIRNAME(["$_am_arg"])`/stamp-h[]$_am_stamp_count])

-# Copyright (C) 2001-2013 Free Software Foundation, Inc.
+# Copyright (C) 2001-2020 Free Software Foundation, Inc.
 #
 # This file is free software; the Free Software Foundation
 # gives unlimited permission to copy and/or distribute it,
@@ -613,7 +608,7 @@ echo "timestamp for $_am_arg" >`AS_DIRNAME(["$_am_arg"])`/stamp-h[]$_am_stamp_co
 # Define $install_sh.
 AC_DEFUN([AM_PROG_INSTALL_SH],
 [AC_REQUIRE([AM_AUX_DIR_EXPAND])dnl
-if test x"${install_sh}" != xset; then
+if test x"${install_sh+set}" != xset; then
  case $am_aux_dir in
  *\ * | *\	*)
    install_sh="\${SHELL} '$am_aux_dir/install-sh'" ;;
@@ -623,7 +618,7 @@ if test x"${install_sh}" != xset; then
 fi
 AC_SUBST([install_sh])])

-# Copyright (C) 2003-2013 Free Software Foundation, Inc.
+# Copyright (C) 2003-2020 Free Software Foundation, Inc.
 #
 # This file is free software; the Free Software Foundation
 # gives unlimited permission to copy and/or distribute it,
@@ -644,7 +639,7 @@ AC_SUBST([am__leading_dot])])

 # Check to see how 'make' treats includes.	            -*- Autoconf -*-

-# Copyright (C) 2001-2013 Free Software Foundation, Inc.
+# Copyright (C) 2001-2020 Free Software Foundation, Inc.
 #
 # This file is free software; the Free Software Foundation
 # gives unlimited permission to copy and/or distribute it,
@@ -652,49 +647,42 @@ AC_SUBST([am__leading_dot])])

 # AM_MAKE_INCLUDE()
 # -----------------
-# Check to see how make treats includes.
+# Check whether make has an 'include' directive that can support all
+# the idioms we need for our automatic dependency tracking code.
 AC_DEFUN([AM_MAKE_INCLUDE],
-[am_make=${MAKE-make}
-cat > confinc << 'END'
+[AC_MSG_CHECKING([whether ${MAKE-make} supports the include directive])
+cat > confinc.mk << 'END'
 am__doit:
-	@echo this is the am__doit target
+	@echo this is the am__doit target >confinc.out
 .PHONY: am__doit
 END
-# If we don't find an include directive, just comment out the code.
-AC_MSG_CHECKING([for style of include used by $am_make])
 am__include="#"
 am__quote=
-_am_result=none
-# First try GNU make style include.
-echo "include confinc" > confmf
-# Ignore all kinds of additional output from 'make'.
-case `$am_make -s -f confmf 2> /dev/null` in #(
-*the\ am__doit\ target*)
-  am__include=include
-  am__quote=
-  _am_result=GNU
-  ;;
-esac
-# Now try BSD make style include.
-if test "$am__include" = "#"; then
-   echo '.include "confinc"' > confmf
-   case `$am_make -s -f confmf 2> /dev/null` in #(
-   *the\ am__doit\ target*)
-     am__include=.include
-     am__quote="\""
-     _am_result=BSD
-     ;;
-   esac
+# BSD make does it like this.
+echo '.include "confinc.mk" # ignored' > confmf.BSD
+# Other make implementations (GNU, Solaris 10, AIX) do it like this.
+echo 'include confinc.mk # ignored' > confmf.GNU
+_am_result=no
+for s in GNU BSD; do
+  AM_RUN_LOG([${MAKE-make} -f confmf.$s && cat confinc.out])
+  AS_CASE([$?:`cat confinc.out 2>/dev/null`],
+      ['0:this is the am__doit target'],
+      [AS_CASE([$s],
+          [BSD], [am__include='.include' am__quote='"'],
+          [am__include='include' am__quote=''])])
+  if test "$am__include" != "#"; then
+    _am_result="yes ($s style)"
+    break
  fi
-AC_SUBST([am__include])
-AC_SUBST([am__quote])
-AC_MSG_RESULT([$_am_result])
-rm -f confinc confmf
-])
+done
+rm -f confinc.* confmf.*
+AC_MSG_RESULT([${_am_result}])
+AC_SUBST([am__include])])
+AC_SUBST([am__quote])])

 # Fake the existence of programs that GNU maintainers use.  -*- Autoconf -*-

-# Copyright (C) 1997-2013 Free Software Foundation, Inc.
+# Copyright (C) 1997-2020 Free Software Foundation, Inc.
 #
 # This file is free software; the Free Software Foundation
 # gives unlimited permission to copy and/or distribute it,
@@ -715,12 +703,7 @@ AC_DEFUN([AM_MISSING_HAS_RUN],
 [AC_REQUIRE([AM_AUX_DIR_EXPAND])dnl
 AC_REQUIRE_AUX_FILE([missing])dnl
 if test x"${MISSING+set}" != xset; then
-  case $am_aux_dir in
-  *\ * | *\	*)
-    MISSING="\${SHELL} \"$am_aux_dir/missing\"" ;;
-  *)
-    MISSING="\${SHELL} $am_aux_dir/missing" ;;
-  esac
+  MISSING="\${SHELL} '$am_aux_dir/missing'"
 fi
 # Use eval to expand $SHELL
 if eval "$MISSING --is-lightweight"; then
@@ -733,7 +716,7 @@ fi

 # Helper functions for option handling.                     -*- Autoconf -*-

-# Copyright (C) 2001-2013 Free Software Foundation, Inc.
+# Copyright (C) 2001-2020 Free Software Foundation, Inc.
 #
 # This file is free software; the Free Software Foundation
 # gives unlimited permission to copy and/or distribute it,
@@ -762,7 +745,7 @@ AC_DEFUN([_AM_SET_OPTIONS],
 AC_DEFUN([_AM_IF_OPTION],
 [m4_ifset(_AM_MANGLE_OPTION([$1]), [$2], [$3])])

-# Copyright (C) 1999-2013 Free Software Foundation, Inc.
+# Copyright (C) 1999-2020 Free Software Foundation, Inc.
 #
 # This file is free software; the Free Software Foundation
 # gives unlimited permission to copy and/or distribute it,
@@ -809,7 +792,7 @@ AC_LANG_POP([C])])
 # For backward compatibility.
 AC_DEFUN_ONCE([AM_PROG_CC_C_O], [AC_REQUIRE([AC_PROG_CC])])

-# Copyright (C) 2001-2013 Free Software Foundation, Inc.
+# Copyright (C) 2001-2020 Free Software Foundation, Inc.
 #
 # This file is free software; the Free Software Foundation
 # gives unlimited permission to copy and/or distribute it,
@@ -828,7 +811,7 @@ AC_DEFUN([AM_RUN_LOG],

 # Check to make sure that the build environment is sane.    -*- Autoconf -*-

-# Copyright (C) 1996-2013 Free Software Foundation, Inc.
+# Copyright (C) 1996-2020 Free Software Foundation, Inc.
 #
 # This file is free software; the Free Software Foundation
 # gives unlimited permission to copy and/or distribute it,
@@ -909,7 +892,7 @@ AC_CONFIG_COMMANDS_PRE(
 rm -f conftest.file
 ])

-# Copyright (C) 2009-2013 Free Software Foundation, Inc.
+# Copyright (C) 2009-2020 Free Software Foundation, Inc.
 #
 # This file is free software; the Free Software Foundation
 # gives unlimited permission to copy and/or distribute it,
@@ -969,7 +952,7 @@ AC_SUBST([AM_BACKSLASH])dnl
 _AM_SUBST_NOTMAKE([AM_BACKSLASH])dnl
 ])

-# Copyright (C) 2001-2013 Free Software Foundation, Inc.
+# Copyright (C) 2001-2020 Free Software Foundation, Inc.
 #
 # This file is free software; the Free Software Foundation
 # gives unlimited permission to copy and/or distribute it,
@@ -997,7 +980,7 @@ fi
 INSTALL_STRIP_PROGRAM="\$(install_sh) -c -s"
 AC_SUBST([INSTALL_STRIP_PROGRAM])])

-# Copyright (C) 2006-2013 Free Software Foundation, Inc.
+# Copyright (C) 2006-2020 Free Software Foundation, Inc.
 #
 # This file is free software; the Free Software Foundation
 # gives unlimited permission to copy and/or distribute it,
@@ -1016,7 +999,7 @@ AC_DEFUN([AM_SUBST_NOTMAKE], [_AM_SUBST_NOTMAKE($@)])

 # Check how to create a tarball.                            -*- Autoconf -*-

-# Copyright (C) 2004-2013 Free Software Foundation, Inc.
+# Copyright (C) 2004-2020 Free Software Foundation, Inc.
 #
 # This file is free software; the Free Software Foundation
 # gives unlimited permission to copy and/or distribute it,
--- a/17
+++ b/17
@@ -1,9 +1,9 @@
 #! /bin/sh
 # Wrapper for compilers which do not understand '-c -o'.

-scriptversion=2012-10-14.11; # UTC
+scriptversion=2018-03-07.03; # UTC

-# Copyright (C) 1999-2013 Free Software Foundation, Inc.
+# Copyright (C) 1999-2020 Free Software Foundation, Inc.
 # Written by Tom Tromey <tromey@cygnus.com>.
 #
 # This program is free software; you can redistribute it and/or modify
@@ -17,7 +17,7 @@ scriptversion=2012-10-14.11; # UTC
 # GNU General Public License for more details.
 #
 # You should have received a copy of the GNU General Public License
-# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.

 # As a special exception to the GNU General Public License, if you
 # distribute this file as part of a program that contains a
@@ -53,7 +53,7 @@ func_file_conv ()
 	  MINGW*)
 	    file_conv=mingw
 	    ;;
-	  CYGWIN*)
+	  CYGWIN* | MSYS*)
 	    file_conv=cygwin
 	    ;;
 	  *)
@@ -67,7 +67,7 @@ func_file_conv ()
 	mingw/*)
 	  file=`cmd //C echo "$file " | sed -e 's/"\(.*\) " *$/\1/'`
 	  ;;
-	cygwin/*)
+	cygwin/* | msys/*)
 	  file=`cygpath -m "$file" || echo "$file"`
 	  ;;
 	wine/*)
@@ -255,7 +255,8 @@ EOF
    echo "compile $scriptversion"
    exit $?
    ;;
-  cl | *[/\\]cl | cl.exe | *[/\\]cl.exe )
+  cl | *[/\\]cl | cl.exe | *[/\\]cl.exe | \
+  icl | *[/\\]icl | icl.exe | *[/\\]icl.exe )
    func_cl_wrapper "$@"      # Doesn't return...
    ;;
 esac
@@ -339,9 +340,9 @@ exit $ret
 # Local Variables:
 # mode: shell-script
 # sh-indentation: 2
-# eval: (add-hook 'write-file-hooks 'time-stamp)
+# eval: (add-hook 'before-save-hook 'time-stamp)
 # time-stamp-start: "scriptversion="
 # time-stamp-format: "%:y-%02m-%02d.%02H"
-# time-stamp-time-zone: "UTC"
+# time-stamp-time-zone: "UTC0"
 # time-stamp-end: "; # UTC"
 # End:
--- a/config.h.in
+++ b/config.h.in
@@ -6,12 +6,15 @@
 /* Define to 1 if you have the `pcap' library (-lpcap). */
 #undef HAVE_LIBPCAP

-/* Define to 1 if you have the <memory.h> header file. */
-#undef HAVE_MEMORY_H
+/* Define to 1 if you have the <minix/config.h> header file. */
+#undef HAVE_MINIX_CONFIG_H

 /* Define to 1 if you have the <stdint.h> header file. */
 #undef HAVE_STDINT_H

+/* Define to 1 if you have the <stdio.h> header file. */
+#undef HAVE_STDIO_H
+
 /* Define to 1 if you have the <stdlib.h> header file. */
 #undef HAVE_STDLIB_H

@@ -30,6 +33,9 @@
 /* Define to 1 if you have the <unistd.h> header file. */
 #undef HAVE_UNISTD_H

+/* Define to 1 if you have the <wchar.h> header file. */
+#undef HAVE_WCHAR_H
+
 /* Name of package */
 #undef PACKAGE

@@ -51,40 +57,98 @@
 /* Define to the version of this package. */
 #undef PACKAGE_VERSION

-/* Define to 1 if you have the ANSI C header files. */
+/* Define to 1 if all of the C90 standard headers exist (not just the ones
+   required in a freestanding environment). This macro is provided for
+   backward compatibility; new code need not use it. */
 #undef STDC_HEADERS

 /* Enable extensions on AIX 3, Interix.  */
 #ifndef _ALL_SOURCE
 # undef _ALL_SOURCE
 #endif
-/* Enable GNU extensions on systems that have them.  */
-#ifndef _GNU_SOURCE
-# undef _GNU_SOURCE
-#endif
-/* Enable threading extensions on Solaris.  */
-#ifndef _POSIX_PTHREAD_SEMANTICS
-# undef _POSIX_PTHREAD_SEMANTICS
-#endif
-/* Enable extensions on HP NonStop.  */
-#ifndef _TANDEM_SOURCE
-# undef _TANDEM_SOURCE
+/* Enable general extensions on macOS.  */
+#ifndef _DARWIN_C_SOURCE
+# undef _DARWIN_C_SOURCE
 #endif
 /* Enable general extensions on Solaris.  */
 #ifndef __EXTENSIONS__
 # undef __EXTENSIONS__
 #endif
+/* Enable GNU extensions on systems that have them.  */
+#ifndef _GNU_SOURCE
+# undef _GNU_SOURCE
+#endif
+/* Enable X/Open compliant socket functions that do not require linking
+   with -lxnet on HP-UX 11.11.  */
+#ifndef _HPUX_ALT_XOPEN_SOCKET_API
+# undef _HPUX_ALT_XOPEN_SOCKET_API
+#endif
+/* Identify the host operating system as Minix.
+   This macro does not affect the system headers' behavior.
+   A future release of Autoconf may stop defining this macro.  */
+#ifndef _MINIX
+# undef _MINIX
+#endif
+/* Enable general extensions on NetBSD.
+   Enable NetBSD compatibility extensions on Minix.  */
+#ifndef _NETBSD_SOURCE
+# undef _NETBSD_SOURCE
+#endif
+/* Enable OpenBSD compatibility extensions on NetBSD.
+   Oddly enough, this does nothing on OpenBSD.  */
+#ifndef _OPENBSD_SOURCE
+# undef _OPENBSD_SOURCE
+#endif
+/* Define to 1 if needed for POSIX-compatible behavior.  */
+#ifndef _POSIX_SOURCE
+# undef _POSIX_SOURCE
+#endif
+/* Define to 2 if needed for POSIX-compatible behavior.  */
+#ifndef _POSIX_1_SOURCE
+# undef _POSIX_1_SOURCE
+#endif
+/* Enable POSIX-compatible threading on Solaris.  */
+#ifndef _POSIX_PTHREAD_SEMANTICS
+# undef _POSIX_PTHREAD_SEMANTICS
+#endif
+/* Enable extensions specified by ISO/IEC TS 18661-5:2014.  */
+#ifndef __STDC_WANT_IEC_60559_ATTRIBS_EXT__
+# undef __STDC_WANT_IEC_60559_ATTRIBS_EXT__
+#endif
+/* Enable extensions specified by ISO/IEC TS 18661-1:2014.  */
+#ifndef __STDC_WANT_IEC_60559_BFP_EXT__
+# undef __STDC_WANT_IEC_60559_BFP_EXT__
+#endif
+/* Enable extensions specified by ISO/IEC TS 18661-2:2015.  */
+#ifndef __STDC_WANT_IEC_60559_DFP_EXT__
+# undef __STDC_WANT_IEC_60559_DFP_EXT__
+#endif
+/* Enable extensions specified by ISO/IEC TS 18661-4:2015.  */
+#ifndef __STDC_WANT_IEC_60559_FUNCS_EXT__
+# undef __STDC_WANT_IEC_60559_FUNCS_EXT__
+#endif
+/* Enable extensions specified by ISO/IEC TS 18661-3:2015.  */
+#ifndef __STDC_WANT_IEC_60559_TYPES_EXT__
+# undef __STDC_WANT_IEC_60559_TYPES_EXT__
+#endif
+/* Enable extensions specified by ISO/IEC TR 24731-2:2010.  */
+#ifndef __STDC_WANT_LIB_EXT2__
+# undef __STDC_WANT_LIB_EXT2__
+#endif
+/* Enable extensions specified by ISO/IEC 24747:2009.  */
+#ifndef __STDC_WANT_MATH_SPEC_FUNCS__
+# undef __STDC_WANT_MATH_SPEC_FUNCS__
+#endif
+/* Enable extensions on HP NonStop.  */
+#ifndef _TANDEM_SOURCE
+# undef _TANDEM_SOURCE
+#endif
+/* Enable X/Open extensions.  Define to 500 only if necessary
+   to make mbstate_t available.  */
+#ifndef _XOPEN_SOURCE
+# undef _XOPEN_SOURCE
+#endif


 /* Version number of package */
 #undef VERSION
-
-/* Define to 1 if on MINIX. */
-#undef _MINIX
-
-/* Define to 2 if the system does not provide POSIX.1 features except with
-   this defined. */
-#undef _POSIX_1_SOURCE
-
-/* Define to 1 if you need to in order for `stat' and other things to work. */
-#undef _POSIX_SOURCE
--- a/3210
+++ b/3210
--- a/configure.ac
+++ b/configure.ac
@@ -1,5 +1,5 @@
 AC_PREREQ(2.60)
-AC_INIT([knock], [0.7], [https://github.com/jvinet/knock/issues])
+AC_INIT([knock], [0.8], [https://github.com/jvinet/knock/issues])
 AM_INIT_AUTOMAKE([dist-xz no-dist-gzip foreign subdir-objects])

 AC_CONFIG_HEADER([config.h])
--- a/10
+++ b/10
@@ -1,9 +1,9 @@
 #! /bin/sh
 # depcomp - compile a program generating dependencies as side-effects

-scriptversion=2013-05-30.07; # UTC
+scriptversion=2018-03-07.03; # UTC

-# Copyright (C) 1999-2013 Free Software Foundation, Inc.
+# Copyright (C) 1999-2020 Free Software Foundation, Inc.

 # This program is free software; you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -16,7 +16,7 @@ scriptversion=2013-05-30.07; # UTC
 # GNU General Public License for more details.

 # You should have received a copy of the GNU General Public License
-# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.

 # As a special exception to the GNU General Public License, if you
 # distribute this file as part of a program that contains a
@@ -783,9 +783,9 @@ exit 0
 # Local Variables:
 # mode: shell-script
 # sh-indentation: 2
-# eval: (add-hook 'write-file-hooks 'time-stamp)
+# eval: (add-hook 'before-save-hook 'time-stamp)
 # time-stamp-start: "scriptversion="
 # time-stamp-format: "%:y-%02m-%02d.%02H"
-# time-stamp-time-zone: "UTC"
+# time-stamp-time-zone: "UTC0"
 # time-stamp-end: "; # UTC"
 # End:
--- a/doc/knock.1.in
+++ b/doc/knock.1.in
@@ -1,4 +1,4 @@
-.TH knock 1 "June 26, 2005" "knockd #VERSION#" ""
+.TH knockd 1 "April 22, 2021" "knockd #VERSION#" ""
 .SH NAME
 knock \- port-knock client
 .SH SYNOPSIS
@@ -18,9 +18,15 @@ can specify the protocol on a per-port basis.  See the example below.
 .B "\-d <t>, \-\-delay <t>"
 Wait <t> milliseconds between each port hit.  This can be used in situations
 where a router mistakes your stream of SYN packets as a port scan and blocks
-them.  If the packet rate is slowed with --delay, then the router should let
+them.  If the packet rate is slowed with \-\-delay, then the router should let
 the packets through.
 .TP
+.B "\-4, \-\-ipv4 <version>"
+Force usage of IPv4.
+.TP
+.B "\-6, \-\-ipv6 <version>"
+Force usage of IPv6.
+.TP
 .B "\-v, \-\-verbose"
 Output verbose status messages.
 .TP
@@ -32,7 +38,7 @@ Syntax help.
 .SH EXAMPLES
 .nf
 knock myserver.example.com 123:tcp 456:udp 789:tcp
-knock -u myserver.example.com 8284 4721 18592 42912
+knock \-u myserver.example.com 8284 4721 18592 42912
 .fi
 .SH SEE ALSO
 \fBknockd\fP is the accompanying port-knock server.
--- a/doc/knockd.1.in
+++ b/doc/knockd.1.in
@@ -1,4 +1,4 @@
-.TH knockd 1 "June 26, 2005" "knockd #VERSION#" ""
+.TH knockd 1 "April 22, 2021" "knockd #VERSION#" ""
 .SH NAME
 knockd \- port-knock server
 .SH SYNOPSIS
@@ -25,12 +25,15 @@ Specify an alternate location for the config file.  Default is
 \fI/etc/knockd.conf\fP.
 .TP
 .B "\-D, \-\-debug"
-Ouput debugging messages.
+Output debugging messages.
 .TP
 .B "\-l, \-\-lookup"
 Lookup DNS names for log entries. This may be a security risk! See section
 \fBSECURITY NOTES\fP.
 .TP
+.B "\-4, \-\-only-ip-v4"
+Ignore packets from IPv6 and handle only IPv4.
+.TP
 .B "\-v, \-\-verbose"
 Output verbose status messages.
 .TP
@@ -60,13 +63,13 @@ firewall and would like to access it discreetly.
 	sequence    = 7000,8000,9000
 	seq_timeout = 10
 	tcpflags    = syn
-	command     = /usr/sbin/iptables -A INPUT -s %IP% --dport 22 -j ACCEPT
+	command     = /usr/sbin/iptables \-A INPUT \-s %IP% \-\-dport 22 \-j ACCEPT

 [closeSSH]
 	sequence    = 9000,8000,7000
 	seq_timeout = 10
 	tcpflags    = syn
-	command     = /usr/sbin/iptables -D INPUT -s %IP% --dport 22 -j ACCEPT
+	command     = /usr/sbin/iptables \-D INPUT \-s %IP% \-\-dport 22 \-j ACCEPT

 .fi
 .RE
@@ -87,9 +90,9 @@ and TCP ports.
 	sequence      = 2222:udp,3333:tcp,4444:udp
 	seq_timeout   = 15
 	tcpflags      = syn,ack
-	start_command = /usr/sbin/iptables -A INPUT -s %IP% -p tcp --syn -j ACCEPT
+	start_command = /usr/sbin/iptables \-A INPUT \-s %IP% \-p tcp \-\-syn \-j ACCEPT
 	cmd_timeout   = 5
-	stop_command  = /usr/sbin/iptables -D INPUT -s %IP% -p tcp --syn -j ACCEPT
+	stop_command  = /usr/sbin/iptables \-D INPUT \-s %IP% \-p tcp \-\-syn \-j ACCEPT

 .fi
 .RE
@@ -112,9 +115,30 @@ sniffing the network).
 	one_time_sequences = /etc/knockd/smtp_sequences
 	seq_timeout        = 15
 	tcpflags           = fin,!ack
-	start_command      = /usr/sbin/iptables -A INPUT -s %IP% -p tcp --dport 25 -j ACCEPT
+	start_command      = /usr/sbin/iptables \-A INPUT \-s %IP% \-p tcp \-\-dport 25 \-j ACCEPT
 	cmd_timeout        = 5
-	stop_command       = /usr/sbin/iptables -D INPUT -s %IP% -p tcp --dport 25 -j ACCEPT
+	stop_command       = /usr/sbin/iptables \-D INPUT \-s %IP% \-p tcp \-\-dport 25 \-j ACCEPT
+	
+.fi
+.TP
+.SH Example #4:
+.RS
+Example to support IPv4 and IPv6. You can provide a dedicated command for each
+of the two protocols.
+
+.nf
+[options]
+	logfile = /var/log/knockd.log
+
+[opencloseSMTP]
+	one_time_sequences = /etc/knockd/smtp_sequences
+	seq_timeout        = 15
+	tcpflags           = fin,!ack
+	start_command      = /usr/sbin/iptables \-A INPUT \-s %IP% \-p tcp \-\-dport 25 \-j ACCEPT
+	start_command_6    = /usr/sbin/ip6tables \-A INPUT \-s %IP% \-p tcp \-\-dport 25 \-j ACCEPT
+	cmd_timeout        = 5
+	stop_command       = /usr/sbin/iptables \-D INPUT \-s %IP% \-p tcp \-\-dport 25 \-j ACCEPT
+	stop_command_6     = /usr/sbin/ip6tables \-D INPUT \-s %IP% \-p tcp \-\-dport 25 \-j ACCEPT
 	
 .fi
 .RE
@@ -181,10 +205,18 @@ etherwake to send the host a WOL packet.
 .TP
 .B "Start_Command = <command>"
 Specify the command to be executed when a client makes the correct
-port-knock.  All instances of \fB%IP%\fP will be replaced with the
+port-knock with IPv4.  All instances of \fB%IP%\fP will be replaced with the
 knocker's IP address.  The \fBCommand\fP directive is an alias for
 \fBStart_Command\fP.
 .TP
+.B "Start_Command_6 = <command>"
+Specify the command to be executed when a client makes the correct
+port-knock with IPv6.  All instances of \fB%IP%\fP will be replaced with the
+knocker's IP address.  The \fBCommand_6\fP directive is an alias for
+\fBStart_Command_6\fP. If not present it will automatically fallback onto
+the same IPV4 \fBStart_Command\fP value. You can use empty value to force
+doing nothing.
+.TP
 .B "Cmd_Timeout = <timeout>"
 Time to wait (in seconds) between \fBStart_Command\fP and \fBStop_Command\fP.
 This directive is optional, only required if \fBStop_Command\fP is used.
@@ -193,6 +225,14 @@ This directive is optional, only required if \fBStop_Command\fP is used.
 Specify the command to be executed when \fBCmd_Timeout\fP seconds have passed 
 since \fBStart_Command\fP has been executed.  All instances of \fB%IP%\fP will
 be replaced with the knocker's IP address.  This directive is optional.
+.TP
+.B "Stop_Command_6 = <command>"
+Specify the command to be executed when \fBCmd_Timeout\fP seconds have passed 
+since \fBStart_Command_6\fP has been executed.  All instances of \fB%IP%\fP will
+be replaced with the knocker's IP address.  This directive is optional.
+If not present it will automatically fallback onto the same IPV4 
+\fBStop_Command\fP value. You can use empty value to force
+doing nothing.
 .SH SECURITY NOTES 
 Using the \fB-l\fP or \fB--lookup\fP commandline option to resolve DNS names
 for log entries may be a security risk!  An attacker may find out the first port
--- a/224
+++ b/224
@@ -1,7 +1,7 @@
 #!/bin/sh
 # install - install a program, script, or datafile

-scriptversion=2011-11-20.07; # UTC
+scriptversion=2020-11-14.01; # UTC

 # This originates from X11R5 (mit/util/scripts/install.sh), which was
 # later released in X11R6 (xc/config/util/install.sh) with the
@@ -41,19 +41,15 @@ scriptversion=2011-11-20.07; # UTC
 # This script is compatible with the BSD install script, but was written
 # from scratch.

+tab='	'
 nl='
 '
-IFS=" ""	$nl"
+IFS=" $tab$nl"

-# set DOITPROG to echo to test this script
+# Set DOITPROG to "echo" to test this script.

-# Don't use :- since 4.3BSD and earlier shells don't like it.
 doit=${DOITPROG-}
-if test -z "$doit"; then
-  doit_exec=exec
-else
-  doit_exec=$doit
-fi
+doit_exec=${doit:-exec}

 # Put in absolute file names if you don't have them in your path;
 # or use environment vars.
@@ -68,22 +64,16 @@ mvprog=${MVPROG-mv}
 rmprog=${RMPROG-rm}
 stripprog=${STRIPPROG-strip}

-posix_glob='?'
-initialize_posix_glob='
-  test "$posix_glob" != "?" || {
-    if (set -f) 2>/dev/null; then
-      posix_glob=
-    else
-      posix_glob=:
-    fi
-  }
-'
-
 posix_mkdir=

 # Desired mode of installed file.
 mode=0755

+# Create dirs (including intermediate dirs) using mode 755.
+# This is like GNU 'install' as of coreutils 8.32 (2020).
+mkdir_umask=22
+
+backupsuffix=
 chgrpcmd=
 chmodcmd=$chmodprog
 chowncmd=
@@ -97,7 +87,7 @@ dir_arg=
 dst_arg=

 copy_on_change=false
-no_target_directory=
+is_target_a_directory=possibly

 usage="\
 Usage: $0 [OPTION]... [-T] SRCFILE DSTFILE
@@ -114,18 +104,28 @@ Options:
     --version  display version info and exit.

  -c            (ignored)
-  -C            install only if different (preserve the last data modification time)
+  -C            install only if different (preserve data modification time)
  -d            create directories instead of installing files.
  -g GROUP      $chgrpprog installed files to GROUP.
  -m MODE       $chmodprog installed files to MODE.
  -o USER       $chownprog installed files to USER.
+  -p            pass -p to $cpprog.
  -s            $stripprog installed files.
+  -S SUFFIX     attempt to back up existing files, with suffix SUFFIX.
  -t DIRECTORY  install into DIRECTORY.
  -T            report an error if DSTFILE is a directory.

 Environment variables override the default commands:
  CHGRPPROG CHMODPROG CHOWNPROG CMPPROG CPPROG MKDIRPROG MVPROG
  RMPROG STRIPPROG
+
+By default, rm is invoked with -f; when overridden with RMPROG,
+it's up to you to specify -f if you want it.
+
+If -S is not specified, no backups are attempted.
+
+Email bug reports to bug-automake@gnu.org.
+Automake home page: https://www.gnu.org/software/automake/
 "

 while test $# -ne 0; do
@@ -143,8 +143,7 @@ while test $# -ne 0; do

    -m) mode=$2
        case $mode in
-	  *' '* | *'	'* | *'
-'*	  | *'*'* | *'?'* | *'['*)
+          *' '* | *"$tab"* | *"$nl"* | *'*'* | *'?'* | *'['*)
            echo "$0: invalid mode: $mode" >&2
            exit 1;;
        esac
@@ -153,16 +152,23 @@ while test $# -ne 0; do
    -o) chowncmd="$chownprog $2"
        shift;;

+    -p) cpprog="$cpprog -p";;
+
    -s) stripcmd=$stripprog;;

-    -t) dst_arg=$2
+    -S) backupsuffix="$2"
+        shift;;
+
+    -t)
+        is_target_a_directory=always
+        dst_arg=$2
        # Protect names problematic for 'test' and other utilities.
        case $dst_arg in
          -* | [=\(\)!]) dst_arg=./$dst_arg;;
        esac
        shift;;

-    -T) no_target_directory=true;;
+    -T) is_target_a_directory=never;;

    --version) echo "$0 $scriptversion"; exit $?;;

@@ -177,6 +183,16 @@ while test $# -ne 0; do
  shift
 done

+# We allow the use of options -d and -T together, by making -d
+# take the precedence; this is for compatibility with GNU install.
+
+if test -n "$dir_arg"; then
+  if test -n "$dst_arg"; then
+    echo "$0: target directory not allowed when installing a directory." >&2
+    exit 1
+  fi
+fi
+
 if test $# -ne 0 && test -z "$dir_arg$dst_arg"; then
  # When -d is used, all remaining arguments are directories to create.
  # When -t is used, the destination is already specified.
@@ -207,6 +223,15 @@ if test $# -eq 0; then
  exit 0
 fi

+if test -z "$dir_arg"; then
+  if test $# -gt 1 || test "$is_target_a_directory" = always; then
+    if test ! -d "$dst_arg"; then
+      echo "$0: $dst_arg: Is not a directory." >&2
+      exit 1
+    fi
+  fi
+fi
+
 if test -z "$dir_arg"; then
  do_exit='(exit $ret); exit $ret'
  trap "ret=129; $do_exit" 1
@@ -250,6 +275,10 @@ do
    dstdir=$dst
    test -d "$dstdir"
    dstdir_status=$?
+    # Don't chown directories that already exist.
+    if test $dstdir_status = 0; then
+      chowncmd=""
+    fi
  else

    # Waiting for this to be detected by the "$cpprog $src $dsttmp" command
@@ -266,70 +295,36 @@ do
    fi
    dst=$dst_arg

-    # If destination is a directory, append the input filename; won't work
-    # if double slashes aren't ignored.
+    # If destination is a directory, append the input filename.
    if test -d "$dst"; then
-      if test -n "$no_target_directory"; then
+      if test "$is_target_a_directory" = never; then
        echo "$0: $dst_arg: Is a directory" >&2
        exit 1
      fi
      dstdir=$dst
-      dst=$dstdir/`basename "$src"`
+      dstbase=`basename "$src"`
+      case $dst in
+	*/) dst=$dst$dstbase;;
+	*)  dst=$dst/$dstbase;;
+      esac
      dstdir_status=0
    else
-      # Prefer dirname, but fall back on a substitute if dirname fails.
-      dstdir=`
-	(dirname "$dst") 2>/dev/null ||
-	expr X"$dst" : 'X\(.*[^/]\)//*[^/][^/]*/*$' \| \
-	     X"$dst" : 'X\(//\)[^/]' \| \
-	     X"$dst" : 'X\(//\)$' \| \
-	     X"$dst" : 'X\(/\)' \| . 2>/dev/null ||
-	echo X"$dst" |
-	    sed '/^X\(.*[^/]\)\/\/*[^/][^/]*\/*$/{
-		   s//\1/
-		   q
-		 }
-		 /^X\(\/\/\)[^/].*/{
-		   s//\1/
-		   q
-		 }
-		 /^X\(\/\/\)$/{
-		   s//\1/
-		   q
-		 }
-		 /^X\(\/\).*/{
-		   s//\1/
-		   q
-		 }
-		 s/.*/./; q'
-      `
-
+      dstdir=`dirname "$dst"`
      test -d "$dstdir"
      dstdir_status=$?
    fi
  fi

+  case $dstdir in
+    */) dstdirslash=$dstdir;;
+    *)  dstdirslash=$dstdir/;;
+  esac
+
  obsolete_mkdir_used=false

  if test $dstdir_status != 0; then
    case $posix_mkdir in
      '')
-	# Create intermediate dirs using mode 755 as modified by the umask.
-	# This is like FreeBSD 'install' as of 1997-10-28.
-	umask=`umask`
-	case $stripcmd.$umask in
-	  # Optimize common cases.
-	  *[2367][2367]) mkdir_umask=$umask;;
-	  .*0[02][02] | .[02][02] | .[02]) mkdir_umask=22;;
-
-	  *[0-7])
-	    mkdir_umask=`expr $umask + 22 \
-	      - $umask % 100 % 40 + $umask % 20 \
-	      - $umask % 10 % 4 + $umask % 2
-	    `;;
-	  *) mkdir_umask=$umask,go-w;;
-	esac
-
        # With -d, create the new directory with the user-specified mode.
        # Otherwise, rely on $mkdir_umask.
        if test -n "$dir_arg"; then
@@ -339,43 +334,49 @@ do
        fi

        posix_mkdir=false
-	case $umask in
-	  *[123567][0-7][0-7])
-	    # POSIX mkdir -p sets u+wx bits regardless of umask, which
-	    # is incompatible with FreeBSD 'install' when (umask & 300) != 0.
-	    ;;
-	  *)
+	# The $RANDOM variable is not portable (e.g., dash).  Use it
+	# here however when possible just to lower collision chance.
 	tmpdir=${TMPDIR-/tmp}/ins$RANDOM-$$
-	    trap 'ret=$?; rmdir "$tmpdir/d" "$tmpdir" 2>/dev/null; exit $ret' 0

+	trap '
+	  ret=$?
+	  rmdir "$tmpdir/a/b" "$tmpdir/a" "$tmpdir" 2>/dev/null
+	  exit $ret
+	' 0
+
+	# Because "mkdir -p" follows existing symlinks and we likely work
+	# directly in world-writeable /tmp, make sure that the '$tmpdir'
+	# directory is successfully created first before we actually test
+	# 'mkdir -p'.
 	if (umask $mkdir_umask &&
-		exec $mkdirprog $mkdir_mode -p -- "$tmpdir/d") >/dev/null 2>&1
+	    $mkdirprog $mkdir_mode "$tmpdir" &&
+	    exec $mkdirprog $mkdir_mode -p -- "$tmpdir/a/b") >/dev/null 2>&1
 	then
 	  if test -z "$dir_arg" || {
 	       # Check for POSIX incompatibilities with -m.
 	       # HP-UX 11.23 and IRIX 6.5 mkdir -m -p sets group- or
 	       # other-writable bit of parent directory when it shouldn't.
 	       # FreeBSD 6.1 mkdir -m -p sets mode of existing directory.
-		   ls_ld_tmpdir=`ls -ld "$tmpdir"`
+	       test_tmpdir="$tmpdir/a"
+	       ls_ld_tmpdir=`ls -ld "$test_tmpdir"`
 	       case $ls_ld_tmpdir in
 		 d????-?r-*) different_mode=700;;
 		 d????-?--*) different_mode=755;;
 		 *) false;;
 	       esac &&
-		   $mkdirprog -m$different_mode -p -- "$tmpdir" && {
-		     ls_ld_tmpdir_1=`ls -ld "$tmpdir"`
+	       $mkdirprog -m$different_mode -p -- "$test_tmpdir" && {
+		 ls_ld_tmpdir_1=`ls -ld "$test_tmpdir"`
 		 test "$ls_ld_tmpdir" = "$ls_ld_tmpdir_1"
 	       }
 	     }
 	  then posix_mkdir=:
 	  fi
-	      rmdir "$tmpdir/d" "$tmpdir"
+	  rmdir "$tmpdir/a/b" "$tmpdir/a" "$tmpdir"
 	else
 	  # Remove any dirs left behind by ancient mkdir implementations.
-	      rmdir ./$mkdir_mode ./-p ./-- 2>/dev/null
+	  rmdir ./$mkdir_mode ./-p ./-- "$tmpdir" 2>/dev/null
 	fi
 	trap '' 0;;
-	esac;;
    esac

    if
@@ -386,7 +387,7 @@ do
    then :
    else

-      # The umask is ridiculous, or mkdir does not conform to POSIX,
+      # mkdir does not conform to POSIX,
      # or it failed possibly due to a race condition.  Create the
      # directory the slow way, step by step, checking for races as we go.

@@ -396,14 +397,12 @@ do
        *)  prefix='';;
      esac

-      eval "$initialize_posix_glob"
-
      oIFS=$IFS
      IFS=/
-      $posix_glob set -f
+      set -f
      set fnord $dstdir
      shift
-      $posix_glob set +f
+      set +f
      IFS=$oIFS

      prefixes=
@@ -417,7 +416,7 @@ do
          prefixes=
        else
          if $posix_mkdir; then
-	    (umask=$mkdir_umask &&
+            (umask $mkdir_umask &&
             $doit_exec $mkdirprog $mkdir_mode -p -- "$dstdir") && break
            # Don't fail if two instances are running concurrently.
            test -d "$prefix" || exit 1
@@ -450,14 +449,25 @@ do
  else

    # Make a couple of temp file names in the proper directory.
-    dsttmp=$dstdir/_inst.$$_
-    rmtmp=$dstdir/_rm.$$_
+    dsttmp=${dstdirslash}_inst.$$_
+    rmtmp=${dstdirslash}_rm.$$_

    # Trap to clean up those temp files at exit.
    trap 'ret=$?; rm -f "$dsttmp" "$rmtmp" && exit $ret' 0

    # Copy the file name to the temp name.
-    (umask $cp_umask && $doit_exec $cpprog "$src" "$dsttmp") &&
+    (umask $cp_umask &&
+     { test -z "$stripcmd" || {
+	 # Create $dsttmp read-write so that cp doesn't create it read-only,
+	 # which would cause strip to fail.
+	 if test -z "$doit"; then
+	   : >"$dsttmp" # No need to fork-exec 'touch'.
+	 else
+	   $doit touch "$dsttmp"
+	 fi
+       }
+     } &&
+     $doit_exec $cpprog "$src" "$dsttmp") &&

    # and set any options; do chmod last to preserve setuid bits.
    #
@@ -474,18 +484,22 @@ do
    if $copy_on_change &&
       old=`LC_ALL=C ls -dlL "$dst"     2>/dev/null` &&
       new=`LC_ALL=C ls -dlL "$dsttmp"  2>/dev/null` &&
-
-       eval "$initialize_posix_glob" &&
-       $posix_glob set -f &&
+       set -f &&
       set X $old && old=:$2:$4:$5:$6 &&
       set X $new && new=:$2:$4:$5:$6 &&
-       $posix_glob set +f &&
-
+       set +f &&
       test "$old" = "$new" &&
       $cmpprog "$dst" "$dsttmp" >/dev/null 2>&1
    then
      rm -f "$dsttmp"
    else
+      # If $backupsuffix is set, and the file being installed
+      # already exists, attempt a backup.  Don't worry if it fails,
+      # e.g., if mv doesn't support -f.
+      if test -n "$backupsuffix" && test -f "$dst"; then
+        $doit $mvcmd -f "$dst" "$dst$backupsuffix" 2>/dev/null
+      fi
+
      # Rename the file to the real destination.
      $doit $mvcmd -f "$dsttmp" "$dst" 2>/dev/null ||

@@ -500,9 +514,9 @@ do
        # file should still install successfully.
        {
          test ! -f "$dst" ||
-	  $doit $rmcmd -f "$dst" 2>/dev/null ||
+          $doit $rmcmd "$dst" 2>/dev/null ||
          { $doit $mvcmd -f "$dst" "$rmtmp" 2>/dev/null &&
-	    { $doit $rmcmd -f "$rmtmp" 2>/dev/null; :; }
+            { $doit $rmcmd "$rmtmp" 2>/dev/null; :; }
          } ||
          { echo "$0: cannot unlink or rename $dst" >&2
            (exit 1); exit 1
@@ -519,9 +533,9 @@ do
 done

 # Local variables:
-# eval: (add-hook 'write-file-hooks 'time-stamp)
+# eval: (add-hook 'before-save-hook 'time-stamp)
 # time-stamp-start: "scriptversion="
 # time-stamp-format: "%:y-%02m-%02d.%02H"
-# time-stamp-time-zone: "UTC"
+# time-stamp-time-zone: "UTC0"
 # time-stamp-end: "; # UTC"
 # End:
--- a/knockd.conf
+++ b/knockd.conf
@@ -13,3 +13,9 @@
 	command     = /usr/sbin/iptables -D INPUT -s %IP% -p tcp --dport 22 -j ACCEPT
 	tcpflags    = syn

+[openHTTPS]
+	sequence    = 12345,54321,24680,13579
+	seq_timeout = 5
+	command     = /usr/local/sbin/knock_add -i -c INPUT -p tcp -d 443 -f %IP%
+	tcpflags    = syn
+
--- a/16
+++ b/16
@@ -1,9 +1,9 @@
 #! /bin/sh
 # Common wrapper for a few potentially missing GNU programs.

-scriptversion=2013-10-28.13; # UTC
+scriptversion=2018-03-07.03; # UTC

-# Copyright (C) 1996-2013 Free Software Foundation, Inc.
+# Copyright (C) 1996-2020 Free Software Foundation, Inc.
 # Originally written by Fran,cois Pinard <pinard@iro.umontreal.ca>, 1996.

 # This program is free software; you can redistribute it and/or modify
@@ -17,7 +17,7 @@ scriptversion=2013-10-28.13; # UTC
 # GNU General Public License for more details.

 # You should have received a copy of the GNU General Public License
-# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.

 # As a special exception to the GNU General Public License, if you
 # distribute this file as part of a program that contains a
@@ -101,9 +101,9 @@ else
  exit $st
 fi

-perl_URL=http://www.perl.org/
-flex_URL=http://flex.sourceforge.net/
-gnu_software_URL=http://www.gnu.org/software
+perl_URL=https://www.perl.org/
+flex_URL=https://github.com/westes/flex
+gnu_software_URL=https://www.gnu.org/software

 program_details ()
 {
@@ -207,9 +207,9 @@ give_advice "$1" | sed -e '1s/^/WARNING: /' \
 exit $st

 # Local variables:
-# eval: (add-hook 'write-file-hooks 'time-stamp)
+# eval: (add-hook 'before-save-hook 'time-stamp)
 # time-stamp-start: "scriptversion="
 # time-stamp-format: "%:y-%02m-%02d.%02H"
-# time-stamp-time-zone: "UTC"
+# time-stamp-time-zone: "UTC0"
 # time-stamp-end: "; # UTC"
 # End:
--- a/src/knock.c
+++ b/src/knock.c
@@ -13,10 +13,9 @@
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
- *  You should have received a copy of the GNU General Public License
- *  along with this program; if not, write to the Free Software
- *  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, 
- *  USA.
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 */

 #include <stdio.h>
@@ -36,11 +35,15 @@
 #include <getopt.h>
 #include <fcntl.h>

-static char version[] = "0.7";
+static char version[] = "0.8";

 #define PROTO_TCP 1
 #define PROTO_UDP 2

+#define IP_DEFAULT AF_UNSPEC
+#define IP_V4 AF_INET
+#define IP_V6 AF_INET6
+
 /* function prototypes */
 void vprint(char *fmt, ...);
 void ver();
@@ -49,13 +52,17 @@ void usage();
 int o_verbose = 0;
 int o_udp     = 0;
 int o_delay   = 0;
+int o_ip      = IP_DEFAULT;

 int main(int argc, char** argv)
 {
 	int sd;
-	struct hostent* host;
-	struct sockaddr_in addr;
 	int opt, optidx = 1;
+	struct addrinfo hints;
+	struct addrinfo *infoptr;
+	char ipname[256];
+	int result;
+	char *hostname;
 	static struct option opts[] =
 	{
 		{"verbose",   no_argument,       0, 'v'},
@@ -63,10 +70,12 @@ int main(int argc, char** argv)
 		{"delay",     required_argument, 0, 'd'},
 		{"help",      no_argument,       0, 'h'},
 		{"version",   no_argument,       0, 'V'},
+		{"ipv4",      no_argument,       0, '4'},
+		{"ipv6",      no_argument,       0, '6'},
 		{0, 0, 0, 0}
 	};

-	while((opt = getopt_long(argc, argv, "vud:hV", opts, &optidx))) {
+	while((opt = getopt_long(argc, argv, "vud:hV46", opts, &optidx))) {
 		if(opt < 0) {
 			break;
 		}
@@ -76,6 +85,8 @@ int main(int argc, char** argv)
 			case 'u': o_udp = 1; break;
 			case 'd': o_delay = (int)atoi(optarg); break;
 			case 'V': ver();
+			case '4': o_ip = IP_V4; break;
+			case '6': o_ip = IP_V6; break;
 			case 'h': /* fallthrough */
 			default: usage();
 		}
@@ -89,18 +100,19 @@ int main(int argc, char** argv)
 		exit(1);
 	}

-	host = gethostbyname(argv[optind++]);
-	if(host == NULL) {
-		fprintf(stderr, "Cannot resolve hostname\n");
-		exit(1);
-	}
+	/* prepare hints to select ipv4 or v6 if asked */
+	memset(&hints, 0, sizeof hints);
+	hints.ai_family = o_ip;
+	hostname = argv[optind++];
+
 	for(; optind < argc; optind++) {
-		unsigned short port, proto = PROTO_TCP;
+		unsigned short proto = PROTO_TCP;
+		const char *port;
 		char *ptr, *arg = strdup(argv[optind]);

 		if((ptr = strchr(arg, ':'))) {
 			*ptr = '\0';
-			port = atoi(arg);
+			port = arg;
 			arg = ++ptr;
 			if(!strcmp(arg, "udp")) {
 				proto = PROTO_UDP;
@@ -108,18 +120,27 @@ int main(int argc, char** argv)
 				proto = PROTO_TCP;
 			}
 		} else {
-			port = atoi(arg);
+			port = arg;
 		}

+		/* get host and port based on hints */
+		result = getaddrinfo(hostname, port, &hints, &infoptr);
+		if(result) {
+			fprintf(stderr, "Failed to resolve hostname '%s' on port %s\n", hostname, port);
+			fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(result));
+			exit(1);
+		}
+
+		/* create socket */
 		if(o_udp || proto == PROTO_UDP) {
-			sd = socket(PF_INET, SOCK_DGRAM, 0);
+			sd = socket(infoptr->ai_family, SOCK_DGRAM, 0);
 			if(sd == -1) {
 				fprintf(stderr, "Cannot open socket\n");
 				exit(1);
 			}
 		} else {
 			int flags;
-			sd = socket(PF_INET, SOCK_STREAM, 0);
+			sd = socket(infoptr->ai_family, SOCK_STREAM, 0);
 			if(sd == -1) {
 				fprintf(stderr, "Cannot open socket\n");
 				exit(1);
@@ -127,19 +148,22 @@ int main(int argc, char** argv)
 			flags = fcntl(sd, F_GETFL, 0);
 			fcntl(sd, F_SETFL, flags | O_NONBLOCK);
 		}
-		memset(&addr, 0, sizeof(addr));
-		addr.sin_family = AF_INET;
-		addr.sin_addr.s_addr = *((long*)host->h_addr_list[0]);
-		addr.sin_port = htons(port);
+
+		/* extract ip as string (v4 or v6) */
+		getnameinfo(infoptr->ai_addr, infoptr->ai_addrlen, ipname, sizeof(ipname), NULL, 0, NI_NUMERICHOST);
+
+		/* connect or send UDP packet */
 		if(o_udp || proto == PROTO_UDP) {
-			vprint("hitting udp %s:%u\n", inet_ntoa(addr.sin_addr), port);
-			sendto(sd, "", 1, 0, (struct sockaddr*)&addr, sizeof(addr));
+			vprint("hitting udp %s:%s\n", ipname, port);
+			sendto(sd, "", 1, 0, infoptr->ai_addr, infoptr->ai_addrlen);
 		} else {
-			vprint("hitting tcp %s:%u\n", inet_ntoa(addr.sin_addr), port);
-			connect(sd, (struct sockaddr*)&addr, sizeof(struct sockaddr));
+			vprint("hitting tcp %s:%s\n", ipname, port);
+			connect(sd, infoptr->ai_addr, infoptr->ai_addrlen);
 		}
+
 		close(sd);
 		usleep(1000*o_delay);
+		freeaddrinfo(infoptr);
 	}

 	return(0);
@@ -161,6 +185,8 @@ void usage() {
 	printf("options:\n");
 	printf("  -u, --udp            make all ports hits use UDP (default is TCP)\n");
 	printf("  -d, --delay <t>      wait <t> milliseconds between port hits\n");
+	printf("  -4, --ipv4           Force usage of IPv4\n");
+	printf("  -6, --ipv6           Force usage of IPv6\n");
 	printf("  -v, --verbose        be verbose\n");
 	printf("  -V, --version        display version\n");
 	printf("  -h, --help           this help\n");
--- a/src/knock_helper_ipt.sh
+++ b/src/knock_helper_ipt.sh
@@ -0,0 +1,189 @@
+#!/bin/sh
+
+# Original version to add non-duplicated rules by Greg Kuchyt (greg.kuchyt@gmail.com)
+# Updated to handle deletes and be generic by Paul Rogers (paul.rogers@flumps.org)
+
+SCRIPT_NAME=$(basename $0)
+
+AWK="/bin/awk"
+GREP="/bin/grep"
+IPTABLES="/sbin/iptables"
+SORT="/bin/sort"
+
+COMMENT_APP="Append "
+COMMENT_DEL="Delete "
+COMMENT_INS="Insert "
+COMMENT_DEFAULT="by knockd"
+
+IPT_CHAIN="INPUT"
+IPT_METHOD=""
+IPT_COMMENT=""
+IPT_SRC_IP=""
+IPT_DST_PORT=""
+IPT_PROTO="tcp"
+IPT_RULE_TARGET="ACCEPT"
+
+DRY_RUN=0
+SEEN=0
+VERBOSE=0
+
+usage() {
+	echo "Usage: $SCRIPT_NAME -a|-i|-x -f SRC_IP_ADDR -d DST_PORT [-p|-c|-m|-t|-h|-v]"
+	echo "Options:"
+	echo "-a|--append      Action: append a rule to NetFilter"
+	echo "-i|--insert      Action: insert a rule to NetFiler"
+	echo "-x|--delete      Action: delete a rule from NetFilter"
+	echo "-f|--srcaddr     The source IP address to be used"
+	echo "-d|--dstport     The destination port to be used in the rule"
+	echo "-p|--proto       The protocol that the rule applies to; default: $IPT_PROTO"
+	echo "-c|--chain       The NetFilter chain to apply the change to; default: $IPT_CHAIN"
+	echo "-m|--comment     Overide default comment text: '$COMMENT_DEFAULT'"
+	echo "-t|--test        Test run - don't actually perform an update to NetFilter"
+	echo "-h|--help        Print this informational screen and exit"
+	echo "-v|--verbose     Print verbose information about actions"
+}
+
+ARGS=$(getopt -o aixf:d:p:c:m::thv -l "append,insert,delete,srcaddr:,dstport:,proto:,chain:,comment::,test,help,verbose" -n $SCRIPT_NAME -- "$@")
+
+if [ $? -ne 0 ];
+then
+        echo "$SCRIPT_NAME - Error! Invalid arguments"
+        usage
+        exit 1
+fi
+
+eval set -- "$ARGS"
+
+while true; do
+        case "$1" in
+		-a|--append)
+			IPT_METHOD="-A"
+			shift;
+		;;
+		-x|--delete)
+			IPT_METHOD="-D"
+			shift;
+		;;
+		-i|--insert)
+			IPT_METHOD="-I"
+			shift;
+		;;
+		-f|--srcaddr)
+			IPT_SRC_IP=$2
+			shift 2;
+		;;
+		-d|--dstport)
+			IPT_DST_PORT=$2
+			shift 2;
+		;;
+		-p|--proto)
+			IPT_PROTO=$2
+			shift 2;
+		;;
+		-c|--chain)
+			IPT_CHAIN=$2
+			shift 2;
+		;;
+		-m|--comment)
+			case "$2" in
+				"")
+					IPT_COMMENT=$COMMENT_DEFAULT;
+					shift 2;;
+				*)
+					IPT_COMMENT=$2;
+					shift 2 ;;
+			esac
+		;;
+		-t|--test)
+			DRY_RUN=1
+                        shift;
+                ;;
+		-h|--help)
+			usage
+			shift;
+			exit
+		;;
+		-v|--verbose)
+			VERBOSE=1
+			shift;
+		;;
+                --)
+                        shift;
+                        break;
+                ;;
+        esac
+done
+
+# Begin sanity checks
+if [ -z "$IPT_SRC_IP" ]; then
+	echo "$SCRIPT_NAME - Error! Source IP address required"
+	usage
+	exit 1
+fi
+
+if [ -z "$IPT_DST_PORT" ]; then
+	echo "$SCRIPT_NAME - Error! Destination port required"
+	usage
+	exit 1
+fi
+
+if [ -z "$IPT_METHOD" ]; then
+	echo "$SCRIPT_NAME - Error! Valid action option not specified"
+fi
+
+case "$IPT_METHOD" in
+	-A)
+		IPT_COMMENT="$COMMENT_APP $IPT_COMMENT"
+		;;
+	-I)
+		IPT_COMMENT="$COMMENT_INS $IPT_COMMENT"
+		;;
+	-D)
+		IPT_COMMENT="$COMMENT_DEL $IPT_COMMENT"
+		;;
+esac
+
+if [ "$VERBOSE" -eq 1 ]; then
+	echo "$SCRIPT_NAME - Testing rule"
+	echo "$SCRIPT_NAME - action: $IPT_METHOD _ src: $IPT_SRC_IP _ dstport: $IPT_DST_PORT _ proto: $IPT_PROTO _ chain: $IPT_CHAIN _ comment: $IPT_COMMENT"
+fi
+
+COMMENT=""
+if [ -n "$IPT_COMMENT" ]; then
+	COMMENT="-m comment --comment '$IPT_COMMENT'"
+fi
+
+$IPTABLES -L $IPT_CHAIN &> /dev/null
+if [ 0 -ne "$?" ]; then
+	echo "$SCRIPT_NAME - Error: $IPT_CHAIN is not a valid NetFilter chain"
+	exit
+fi
+# End sanity checks
+
+# Dupe checking
+for IP in `$IPTABLES -n -L $IPT_CHAIN | $GREP $IPT_RULE_TARGET | $AWK '{print $4}' | $SORT -u`;
+do
+	if [ "$VERBOSE" -eq 1 ]; then
+		echo "$SCRIPT_NAME - $IP"
+	fi
+
+	if [ "$IPT_SRC_IP" == "$IP" ]; then
+		SEEN=1
+	fi
+done
+
+if [ "$VERBOSE" -eq 1 ]; then
+	echo "$SCRIPT_NAME - Seen: $SEEN"
+fi
+
+
+if [ "$SEEN" -eq 0 ]; then
+	if [ "$VERBOSE" -eq 1 ]; then
+		echo "$SCRIPT_NAME - $IPT_COMMENT"
+		echo $IPTABLES $IPT_METHOD $IPT_CHAIN -s $IPT_SRC_IP -p $IPT_PROTO --dport $IPT_DST_PORT -j $IPT_RULE_TARGET $COMMENT
+	fi
+
+	if [ "$DRY_RUN" -eq 0 ]; then
+		eval $IPTABLES $IPT_METHOD $IPT_CHAIN -s $IPT_SRC_IP -p $IPT_PROTO --dport $IPT_DST_PORT -j $IPT_RULE_TARGET $COMMENT
+	fi
+fi
--- a/src/knockd.c
+++ b/src/knockd.c
--- a/src/list.c
+++ b/src/list.c
@@ -13,10 +13,9 @@
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
- *  You should have received a copy of the GNU General Public License
- *  along with this program; if not, write to the Free Software
- *  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, 
- *  USA.
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 */

 #include <stdlib.h>
@@ -28,7 +27,7 @@ PMList* list_new()
 {
 	PMList *list = NULL;
 	
-	list = (PMList*)malloc(sizeof(PMList));
+	list = (PMList*)calloc(1, sizeof(PMList));
 	if(list == NULL) {
 		return(NULL);
 	}
--- a/src/list.h
+++ b/src/list.h
@@ -13,10 +13,9 @@
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
- *  You should have received a copy of the GNU General Public License
- *  along with this program; if not, write to the Free Software
- *  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, 
- *  USA.
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 */
 #ifndef _PAC_LIST_H
 #define _PAC_LIST_H