Connecting to hosts

Everything on this page is per host and off unless you turn it on, with one exception: post-quantum key exchange, which is on for every connection and has been since the first release.

Several of these options trade something real for what they give you. Where that is the case, this page says what the trade is rather than only what the feature does.

Two-factor logins

If a host asks for a one-time code, a push confirmation or a forced password change, UniSSH asks you. Nothing to configure.

The mechanism is SSH’s keyboard-interactive. A stored password still answers a plain PAM round by itself — that is the case where the server only wants the password it already has and there is nothing for you to decide. A second round, which is where a TOTP code or a Duo push lives, is put to you.

The field is masked when the server says the answer is secret and shown when it says otherwise, because that flag is the server telling you whether you are typing a login name or a code.

Hardware keys, via the system ssh-agent

Set a host’s authentication to System agent and pick an identity. Signing then happens in your operating system’s ssh-agent rather than in UniSSH.

That is the route to hardware, and it covers more than one kind at once:

• FIDO/U2F security keys (YubiKey and friends)
• PKCS#11 smart cards
• Secure Enclave keys on macOS
• 1Password’s SSH agent, gpg-agent, and anything else speaking the protocol

The picker lists what the agent currently holds, so “my token isn’t plugged in” is visible before a connection fails rather than after.

What this costs

For a host set up this way, the guarantee that a key never leaves UniSSH does not apply — the key was never UniSSH’s. It lives in the agent, and anything that can reach the agent socket can ask it to sign. That is the same trust the tool providing the key already asks of you, and it is the price of a token being usable at all. UniSSH stores only the public key, which is a handle, not a secret. See the threat model.

If UniSSH cannot find the key in the agent it says so and names the fix, instead of reporting a generic authentication failure that would send you to check the key when the real problem is an unplugged token.

Forwarding the agent

Off by default. Turn it on for a host and programs running there — git, scp, ssh to a third machine — can sign with the key that session is using, without the key ever being copied to that host.

UniSSH’s forwarding is deliberately narrower than OpenSSH’s:

• One key. Only the key this connection authenticated with is offered. OpenSSH forwards your whole agent, which hands the remote host a list of every key you hold — in effect a map of everywhere you log in — and lets it request a signature with any of them.
• Every signature asks you. A prompt names the host and, when the payload is an SSH login, the identity that signature would log in as. Refusing is the default: closing the dialog, dismissing it, or leaving it unanswered all decline.
• Read-only. Requests to add, remove, lock or unlock keys are refused outright. Those arrive from the remote machine, and a forwarded agent has no business honouring them.
• Target only. A jump host never gets a forwarded agent. A bastion is precisely the machine ProxyJump exists to keep your key away from.

What this costs

While a forwarded session is open, anything that can reach the socket on that host can ask you to sign — every process running as your user there, not only root. The confirmation prompt is what makes this visible instead of silent. If you do not need git or ssh to work on the remote machine, leave it off: ProxyJump already reaches a target through a bastion without forwarding anything.

Snippets and startup commands

A snippet is a command you keep. It is vault content, so it is encrypted at rest and syncs with everything else — a command line routinely carries hostnames, ticket ids and the occasional pasted token.

• ⌘K finds snippets by name or by what they run, and types the chosen one into the active pane. It does not execute: pressing Enter stays your decision, so a mis-click cannot be destructive.
• Per host, snippets can be marked to run on connect. Those do execute, in the order you picked them — a startup command that needed a manual Enter every time would do nothing for anyone.

Session recording

Per host, records what happens in interactive sessions as asciicast v2, encrypted in the vault like any other item.

Because the format is standard, a recording can be exported to a file and played with asciinema by someone who does not run UniSSH — which is what makes it usable as evidence rather than only as a convenience.

Capped at 8 MB per session. A recording that reaches the cap is marked truncated rather than ending quietly, because a partial recording that looks complete is worse than no recording.

Where your output lives

Enabling this stops terminal output being ephemeral. It is stored and synced like any vault item — encrypted, so your server cannot read it — but anything that appeared on screen, including a token echoed by a command or a dumped config, is now kept.

Algorithm policy

By default UniSSH negotiates a vetted set, with hybrid post-quantum key exchange first: mlkem768x25519-sha256 (ML-KEM-768 + X25519, NIST FIPS 203), falling back to classical curve25519 on servers that do not offer it. Hybrid means an attacker has to break both halves, and it is what defends traffic recorded today against being decrypted later.

Modern only (Settings → Connection) tightens that: post-quantum key exchange required with no classical fallback, Ed25519 host keys, AEAD ciphers, encrypt-then-MAC. A server that cannot meet it stops connecting rather than quietly downgrading — which is the point, and why it is off by default.

There is deliberately no “compatibility” mode that re-enables SHA-1 MACs, CBC ciphers or small DH groups. The defaults already exclude them; a switch that put them back would be a footgun in a client whose argument is that its defaults can be trusted.

Importing ~/.ssh/config

UniSSH applies Host patterns (including ! negation), HostName, Port, User, IdentityFile, ProxyJump, LocalForward, RemoteForward, DynamicForward, SetEnv, ServerAliveInterval, ConnectTimeout and Compression, and follows Include.

Everything it cannot apply — ProxyCommand, Match blocks, anything else — is reported with its line number in the import preview. A real config is mostly directives no GUI client implements, and importing one in silence leaves you believing your ProxyCommand came across when it did not.