Host key verification
Trust on first use
Section titled “Trust on first use”The first time you connect to a server, SigilTTY shows its host key fingerprint. When you accept, the fingerprint is recorded for that server.
Every connection after that
Section titled “Every connection after that”On each later connection the presented host key is compared against the recorded fingerprint before any credentials are sent. If it doesn’t match, the connection is blocked — a changed host key can mean the server was reinstalled, or that something is intercepting your connection. You decide explicitly whether to trust the new key.
Jump chains
Section titled “Jump chains”With jump hosts, every hop is verified independently against its own recorded fingerprint. A compromised intermediate can’t silently swap the target.
When a host key changes
Section titled “When a host key changes”On a mismatch, the connection is dropped immediately — before any credentials leave your device. The terminal prints both fingerprints, and a Host Key Changed dialog shows the known and new keys side by side.
Nothing is updated until you choose Trust New Key; after that, reconnect manually. Only trust the new key when the change is one you expected — a server you know was reinstalled. If it wasn’t, treat the mismatch as a possible interception and investigate before connecting.
Managing known hosts
Section titled “Managing known hosts”Trust is recorded in one global table, keyed by host:port — not per server profile. Accept a
fingerprint once and it holds everywhere that endpoint appears: other profiles pointing at the
same host, hops in a jump chain, and ad-hoc Quick Connect sessions.
Settings › Known Hosts lists every trusted endpoint with its fingerprint and the date it was added. From there you can:
- Copy Fingerprint — to compare against what the server’s administrator publishes.
- Forget… — remove a single entry, with a confirmation. The next connection to that endpoint goes back to trust on first use.
Deleting a server profile does not forget its host trust — the entry stays in the table until you forget it here. Known hosts sync between your devices via iCloud sync, so a host you trusted on your Mac is already trusted on your iPhone.