Read the SSH configuration sshd and ssh really use [10m] - #29
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The probes read sshd_config and sshd_config.d/*.conf under /etc/ssh. Include can pull in any file (macOS reads /etc/ssh/crypto.conf), the FreeBSD package and appliances use /usr/local/etc/ssh, and a daemon started with -f reads another file entirely. And since OpenSSH 10.4, sshd -T and sshd -G print directive names in mixed case (PermitRootLogin), so a filter like grep '^permitrootlogin ' finds nothing and the security and fleet audits read an empty config. New rules/ssh-config.md: - one sshd probe that takes a -f from the running daemon, tries sshd -G (OpenSSH 9.3+, no host keys needed) and falls back to sshd -T, and lists every file read (sshd -dd); - the ssh -v -G client probe, per account that connects out; - grep -i on every filter over that output. The security audit's fallback and weak-algorithm check and the fleet audit's sshd probe use grep -i. The security audit reports a server's SSH client (StrictHostKeyChecking no, a /dev/null known-hosts file). rules/<family>.md name sshd's unit, config directory, auth log, checksum tool and job scheduler per OS. CLAUDE.md points to the rule. Tested against a local sshd (OpenSSH 10.3) with an Include outside sshd_config.d and a daemon started with -f. The mixed case of 10.4 is taken from the upstream commit (f6acdce690), not tested. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
This was referenced Sep 19, 2026
# Conflicts: # .claude/skills/heinzel-fleet-audit/references/probes.md # .claude/skills/heinzel-security/references/ssh.md
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Symptom: Since OpenSSH 10.4,
sshd -TprintsPermitRootLogininstead ofpermitrootlogin, so the audits'grep '^permitrootlogin 'finds nothing and judges sshd settings they never saw. AnIncludeoutsidesshd_config.d, FreeBSD's/usr/local/etc/sshand a daemon started with-fare missed too; details in #28.Change: New
rules/ssh-config.md: one sshd probe that carries a-ffrom the running daemon over, triessshd -Gand falls back tosshd -T, and lists every file read; thessh -v -Gclient probe per account that connects out;grep -ion all such output. The security and fleet audits filter case-insensitively, and the security audit reports a server's SSH client.rules/<family>.mdname sshd's unit, paths, log and checksum tool.CLAUDE.mdpoints to the rule.Size: Split out of #14, which now builds on it; independent of #13.
Verified: guard test matrix 551 passed, 0 failed. Probes run against a local OpenSSH 10.3 sshd with an
Includeoutsidesshd_config.dand a-fdaemon.An AI agent wrote this text in my name. I know that is problematic.
Part of #27.
Closes #28.