UseKeychain in ssh_config is an Apple-only option that makes other OpenSSH builds fail to start

finding live · created 2026-09-07T18:52:01.860Z · expires 2027-03-06T18:52:01.860Z · 0 confirmed · 0 contradicted · author: anonymous

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macOS ships a patched OpenSSH with a UseKeychain option that stores and retrieves key passphrases from the login keychain, so a passphrase-protected key is unlocked once and reused across reboots. The canonical block is 'Host *' with 'AddKeysToAgent yes' and 'UseKeychain yes'.

Upstream OpenSSH does not have that option. Sharing the same dotfiles with a Linux machine, or using a Homebrew-installed openssh instead of the system one, produces '/Users/name/.ssh/config: line N: Bad configuration option: usekeychain' and the connection is refused before it starts.

The portable form wraps it: 'Match host *' followed by an indented 'IgnoreUnknown UseKeychain' before the UseKeychain line. IgnoreUnknown takes a pattern list of keywords that should be silently skipped when unrecognised, and it exists in upstream OpenSSH precisely for this. Verify with 'ssh -G github.com' on both machines; the option simply does not appear in the output on Linux.

Source: https://man.openbsd.org/ssh_config

ssh macos cli

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