920edc50b37543e9203be4dc2a7520fdbd4ce7c6
4
Commits
| Author | SHA1 | Message | Date | |
|---|---|---|---|---|
  57_WolveandClaude Opus 5
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a3843d3d85 |
fix(ssh): build KexAlgorithms from what OpenSSH supports, add classic opt-in
Hardened hosts rejected clients that implement the very same key exchange. The
KEX list was assembled from version arithmetic and emitted only the
standardised spellings:
KexAlgorithms mlkem768x25519-sha256,sntrup761x25519-sha512
OpenSSH called that hybrid sntrup761x25519-sha512@openssh.com before the method
was standardised (8.5, in the default proposal from 8.9) and
sntrup761x25519-sha512 after (9.9), and KEXINIT matches names byte-exactly with
no alias resolution -- so every client older than the rename was refused with
"no matching key exchange method found" despite implementing the algorithm. The
same arithmetic was a latent server-side bug: on OpenSSH 9.0-9.8 it wrote the
post-standardisation name into sshd_config, which those builds do not know, and
sshd fatals on an unknown KexAlgorithms token rather than starting.
Ask the binary instead of guessing. oslib gains kex_supported(),
ssh_kex_pq_list(), ssh_kex_classic_list(), ssh_kex_list() and ssh_kex_has_pq(),
which filter candidates through `ssh -Q kex` and offer every spelling the host
actually has. Version thresholds are gone, and with them both failure modes --
including on distros whose backports make the version string meaningless.
SSH_ALLOW_CLASSIC_KEX=1 (off by default) additionally offers curve25519-sha256
and its @libssh.org spelling. Some clients have no PQ method at all: notably
Windows' in-box ssh.exe, which is not merely old -- Microsoft's fork compiles
sntrup761 out because it needs C99 VLAs that MSVC lacks, so even a fully patched
9.5p2 reports zero PQ methods. The knob is a real trade and says so in the
warning, the generated sshd_config comment, and the README: such a session is
safe against a classical attacker but has no store-now-decrypt-later protection.
Modern clients still negotiate PQ, since the client's preference order decides.
Three defects found reviewing the above, fixed here:
- the printed pre-reload verification command pinned the server's full list via
`-o KexAlgorithms=`, which ssh rejects at option-parse time when the client
lacks any one name. That made the one safety gate before a wholesale
sshd_config swap a false negative for exactly the clients this commit admits.
Dropped, matching harden-jumphost.sh.
- the no-PQ branch was unreachable: without the opt-in the classical names are
never collected, so a host with no PQ hybrid died reporting "no usable key
exchange method" instead of the actionable message written for it. The branch
now keys off a separate PQ probe, and the empty-list die is narrowed to a
genuinely empty `ssh -Q kex`.
- SSH_VER is cosmetic but its grep could abort the whole run under pipefail on
any banner that does not match (vendor forks, OpenSSH_for_Windows_9.5p2) --
silently, with no message. Guarded.
Wired through cloud-init/base.yml and jumphost.yml, since harden-ssh.sh rewrites
sshd_config wholesale on every run and a hand edit there does not survive.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
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57_WolveandClaude Opus 5
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339c62a1b0 |
fix(firewall): skip the host firewall on Proxmox
Proxmox VE and Proxmox Mail Gateway are Debian, so os_detect classified them as debian and harden-firewall.sh installed the iptables backend on top of pve-firewall. The conflict is not the obvious one. pve-firewall does NOT delete third-party rules: it restores with `iptables-restore -n` (--noflush), only ever flushes chains matching its own patterns (PVEFW-*, tapNiM-*, vethNiM-*, fwbrN-*, GROUP-*), appends `-A INPUT -j PVEFW-INPUT` only when that hook is missing, and never sets a built-in chain's policy. Our rules survive it. We are the ones doing damage: - `-P INPUT DROP` is ours alone, and PVEFW-HOST-IN RETURNs on accept rather than ACCEPTing (it still has to check tap rules), so traffic Proxmox explicitly allowed falls out of its chain onto our DROP -- we silently override the platform's own accepts. - netfilter-persistent restores at boot with a full iptables-restore (no --noflush), wiping PVE's hook along with everything else until the daemon re-appends it ~10s later. - a deny-by-default chain has to enumerate the whole platform to stay usable: 8006, 5405-5412/udp corosync, 60000-60050, 5900-5999, 3128, 22, 111/udp, plus Ceph when hyperconverged -- and `-i lo`, or pveproxy loses pvedaemon on :85. - under the nftables backend (PVE 8.2+) an nft DROP beats an iptables ACCEPT, so our rules would not even be authoritative. So don't manage a firewall there at all: - oslib: is_proxmox() -- matches hosts shipping pve-firewall (VE/PMG), not PBS. - harden-firewall.sh: a third backend, "pve", that deliberately does nothing. apply explains and exits 0, allow/deny refuse loudly rather than fake success for a rule they didn't add, list shows pve-firewall status. It overrides an explicit FW_BACKEND; FW_IGNORE_PVE=1 is the one escape hatch. - harden-ssh.sh / harden-jumphost.sh: skip the firewall and install the standalone INPUT -> sshguard boot hook instead. That jump is safe alongside pve-firewall -- inserted with -I, it sits ahead of the appended PVEFW-INPUT hook and keeps first look at NEW connections. Detection only helps hosts built from here on, so `disable` cleans up one that was hardened earlier: it detects leftovers (and says which signal fired), sets INPUT ACCEPT *before* flushing so it can't drop the SSH session it runs over, deletes /etc/firewall and the engine, disables boot restore and renames the saved rulesets aside rather than persisting the open state, re-adds the sshguard jump, and restarts pve-firewall. `apply` points at it when it spots leftovers. Documented plainly that skipped is NOT protected: Proxmox's firewall is off by default (cluster-wide enable defaults to 0, and the daemon tears its chains down every ~10s while it is), so these hosts have no host firewall until someone enables it -- and the node panel's "Firewall: Yes" is ignored while the datacenter one says No. Also: svc_disable + fw_restore_services/fw_saved_files in oslib (fw_enable_restore now derives from the former), and usage() prints the whole header block instead of a hardcoded line range. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> |
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57_Wolve
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e23557b4fb
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feat(firewall): add deny-by-default host firewall (harden-firewall.sh)
Add a reusable iptables baseline that hardens hosts with ICMP + SSH defaults and lets deployments register the ports they need. INPUT is deny-by-default (loopback, established, ICMP, SSH on the configured port, plus registered ports); OUTPUT stays open and FORWARD is left untouched so Docker container networking is unaffected. Persistence is native -- no boot hook. Rules are saved and restored by the distro's own package (iptables/ip6tables on Alpine, iptables-persistent on Debian, iptables-services on Alma) via the new oslib helpers install_iptables / fw_save_cmd / fw_enable_restore. The saved ruleset carries the INPUT->sshguard jump, so brute-force protection survives reboot without the old sshguard-iptables hook. A self-contained /usr/local/sbin/firewall-apply rebuilds INPUT from declarative drop-ins under /etc/firewall/ports.d and runs the native save, so deployments add a port without needing the repo present: printf '80/tcp\n443/tcp\n' > /etc/firewall/ports.d/mystack.rule /usr/local/sbin/firewall-apply - SSH port read live from sshd_config (custom bastion ports just work); FW_SSH_SOURCE restricts the source CIDR; FW_ALLOW_PING gates echo - harden-ssh.sh / harden-jumphost.sh install it when ENABLE_FIREWALL=1 (default) and skip the sshguard-only hook; ENABLE_FIREWALL=0 keeps it - cloud-init base.yml / jumphost.yml forward the toggle - the four stack deploy.sh open_web_ports() register 80/443 via the firewall (ufw/firewalld kept as fallback); Docker-published ports bypass INPUT, so this is belt-and-braces and self-documenting - README + cloud-init/README document the mechanism, Docker caveat, and the `disable` recovery path |
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57_Wolve
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7faa9098de
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feat: unified launcher, multi-OS hardening, login alerts & auto-updates
Restructure around a single entry point (automations.sh) with a Gum wizard and a self-extracting bundle for repo-less installs. Add scripts/oslib.sh so the provisioning scripts (setup-host, harden-ssh, harden-jumphost, sshuser) run on Alpine/Debian/Alma; seed root keys from globals/. - ntfy SSH-login alerts (user, source IP, key, region, jump target) via pam_exec - daily auto-updates with AUTO_REBOOT=idle (reboots only when no SSH active) and opt-in Alpine stable-branch upgrades - generic + per-deployment cloud-init; Gitea release workflow on tag - README/LICENSE/.gitignore/.gitattributes (force LF); repo URLs -> Gitea |