Namespace SshSharp

Classes

KnownHostsLookup: The name and port a host key is looked up under in known_hosts (see KnownHostsLookup).

Verifies host keys against OpenSSH known_hosts files, with StrictHostKeyChecking semantics:

A recorded key that matches is trusted; one listed as @revoked is always refused.
A different key of a recorded type ("the host key has changed") is refused, except with No.
An unknown key is refused (Yes), offered to AskHostKey, or recorded and trusted (AcceptNew, No). AcceptNew refuses it when keys of other types are already recorded for the host, so a man in the middle cannot get a weaker key type accepted silently.

New keys are appended to the first user file. The file is rewritten only by UpdateHostKeys, to remove keys the server no longer announces.

SshAgent: An SSH agent (ssh-agent, the Windows OpenSSH agent service, or any agent speaking the same protocol) that holds private keys and signs with them, so the keys never enter this process. List its keys with GetKeysAsync(CancellationToken) and pass them in PrivateKeys; every signature is then made by the agent.

SshAgentDestination: One destination constraint on an agent key (OpenSSH's restrict-destination-v00@openssh.com, ssh-add -h): the key may be used to authenticate to To when reached from From; from this machine when From is null. A key used through agent forwarding needs a constraint for each hop: ssh-add -h jump -h "jump>dest" is two destinations. The agent enforces them through the session binding (session-bind@openssh.com) that ssh and SshSharp send.

SshAgentHost: A host in an agent destination constraint (SshAgentDestination): its name, the user (for the destination only), and the host keys that identify it, or certificate authorities whose host certificates do.

SshAgentHostKey: A host key in a destination constraint, in SSH wire format; with IsCertificateAuthority, a CA key whose host certificates count.

SshAgentKeyConstraints: Limits on a key added to an agent (AddKeyAsync(SshPrivateKey, SshAgentKeyConstraints?, CancellationToken)), as ssh-add -t and ssh-add -c set them.

SshAllowedSigners: An allowed-signers file (ssh-keygen's ALLOWED SIGNERS format, git's gpg.ssh.allowedSignersFile): which keys may sign as which principals, for SshSignature verification as ssh-keygen -Y verify and -Y find-principals do.

SshAuthenticationException: The server refused every authentication method that was tried.

SshAuthenticationPrompt: One question in a keyboard-interactive round.

SshCertificate: An OpenSSH certificate (PROTOCOL.certkeys): a public key signed by a certificate authority, limited to some principals, a validity window, and options. Presented by servers as host keys and used by clients for public-key authentication.

SshChannelTimeout: A channel idle timeout, as OpenSSH's ChannelTimeout sets one (type=interval): channels of ChannelType with no data in either direction for Timeout are closed by the client. See ChannelTimeouts.

SshClient: An authenticated SSH client connection: run commands over it. Create one with ConnectAsync(Stream, SshClientOptions, bool, CancellationToken).

SshClientOptions: Options for SshClient.

SshCommandResult: The outcome of a remote command.

SshConfigConnectOptions: Options for ConnectAsync(string, SshConfigConnectOptions?, CancellationToken), which takes everything else from ssh_config: host name, port, user, identity files, known_hosts and StrictHostKeyChecking, algorithms, ProxyJump, ProxyCommand, ServerAliveInterval, ConnectTimeout and AddressFamily.

SshDynamicPortForwarder: A SOCKS proxy (dynamic forwarding, ssh -D) started by ForwardDynamicPortAsync(IPEndPoint, CancellationToken): applications connect to LocalEndPoint as a SOCKS 4, 4a or 5 proxy (CONNECT, no authentication), and each connection is made by the server to the address the application asked for. Dispose it to stop listening and close the connections.

SshException: The base class for errors raised by SshSharp when talking SSH.

SshExitSignal: The signal that ended a remote program, from the server's exit-signal (RFC 4254 section 6.10).

SshExpect: Drives an interactive program, as expect does: wait until its output shows a prompt or other text, then send the next input. Wrap a shell session (StartShellAsync(SshSessionOptions?, CancellationToken), usually with a terminal) and use ExpectAsync(string, CancellationToken), ReadLineAsync(CancellationToken) and SendLineAsync(string, CancellationToken); timeouts are CancellationTokens.

SshExpectMatch: A match found by SshExpect.

SshGssapiOptions: Kerberos authentication (gssapi-with-mic, RFC 4462; ssh's GSSAPIAuthentication yes), set on Gssapi. The ticket comes from the platform: the logon session on Windows (SSPI), the credential cache (kinit) elsewhere (MIT or Heimdal GSS-API). Needs .NET 10; on .NET 8 the method is not offered.

SshHostKey: The host key the server proved possession of during key exchange. Decide whether to trust it in HostKeyVerifier.

SshHostKeyContext: What a SshHostKeyVerifier is asked to decide: which host this is and the key it proved it holds.

SshHostKeyException: The server's host key was not trusted, changed, or revoked, or the server could not prove it holds the key.

SshHostKeyPrompt: Why a KnownHostsVerifier in Ask mode is asking.

SshHostKeyScanOptions: Options for ScanHostKeysAsync(string, int, SshHostKeyScanOptions?, CancellationToken).

SshHostKeyUpdate: A change to known_hosts that UpdateHostKeys is about to make, for ConfirmHostKeyUpdate.

SshHostKeyVerifier: Decides whether to trust a server's host key. Use KnownHostsVerifier for OpenSSH known_hosts behaviour, Pinned(params string[]) for fixed fingerprints, or FromDelegate(Func<SshHostKeyContext, CancellationToken, ValueTask<bool>>) for your own logic.

SshKeySigner: Signs with a private key that SshSharp never sees: one in Azure Key Vault or AWS KMS, in an HSM behind PKCS#11, on a smart card. Derive from it, then pass it to FromSigner(SshKeySigner, string?) to use the key like any other (for public key authentication, with a certificate, or for SSH signatures). For a key that .NET's RSA or ECDsa already holds, including non-exportable Windows CNG keys, use FromRsa(RSA, string?) or FromECDsa(ECDsa, string?).

SshKeyboardInteractiveRequest: A round of keyboard-interactive authentication (RFC 4256): the server's questions, answered by KeyboardInteractive. All text comes from the server: strip control characters before showing it in a terminal.

SshLocalPortForwarder: A local port forwarding (ssh -L) started by ForwardLocalPortAsync(IPEndPoint, string, int, CancellationToken): connections to LocalEndPoint are relayed through the server to RemoteHost:RemotePort. Dispose it to stop listening and close the forwarded connections.

SshNegotiatedAlgorithms: The algorithms a connection negotiated (they can change at a key re-exchange). See Algorithms.

SshPrivateKey: A private key for public-key authentication. Load one with Parse(string, string?) or LoadAsync(string, string?, CancellationToken). Supported formats: the OpenSSH key format (BEGIN OPENSSH PRIVATE KEY, as ssh-keygen writes by default, also passphrase-protected), PuTTY .ppk (versions 2 and 3, also encrypted), PKCS#8 (BEGIN PRIVATE KEY, and BEGIN ENCRYPTED PRIVATE KEY for RSA and ECDSA), and PKCS#1/SEC1 PEM (BEGIN RSA PRIVATE KEY, BEGIN EC PRIVATE KEY). Key types: Ed25519, ECDSA (nistp256/384/521) and RSA (2048 bits or more).

SshProtocolException: The peer sent data that violates the SSH protocol (malformed packet, bad length, unexpected message).

SshProxy: An HTTP or SOCKS proxy to reach the SSH server through, for networks that allow outbound connections only that way. Set it as Proxy or Proxy, or open a stream with ConnectAsync(string, int, CancellationToken) and pass it to ConnectAsync(Stream, SshClientOptions, bool, CancellationToken).

SshRemotePortForwarder: A remote port forwarding (ssh -R) started by ForwardRemotePortAsync(string, int, string, int, CancellationToken): the server listens on BindAddress:RemotePort, and each connection made to it is relayed to LocalHost:LocalPort as reached from this machine. A remote dynamic forwarding (ForwardRemoteDynamicPortAsync(string, int, Func<string, int, bool>?, CancellationToken), IsDynamic) instead answers each connection as a SOCKS proxy and connects where it asks. Dispose it to cancel the forwarding on the server and close the forwarded connections.

SshRemoteSocketForwarder: A remote Unix-socket forwarding (ssh -R /remote/socket:target) started by ForwardRemoteUnixSocketAsync(string, string, int, CancellationToken): the server listens on the Unix socket RemoteSocketPath, and each connection made to it is relayed to a TCP port (LocalHost:LocalPort) or a Unix socket (LocalSocketPath) reached from this machine. Dispose it to cancel the forwarding on the server and close the forwarded connections.

SshSession: A shell or command running on the server (an SSH session channel), with its input and output as streams. Start one with StartShellAsync(SshSessionOptions?, CancellationToken) or StartCommandAsync(string, SshSessionOptions?, CancellationToken); dispose it to close the channel.

SshSessionOptions: Options for StartShellAsync(SshSessionOptions?, CancellationToken) and StartCommandAsync(string, SshSessionOptions?, CancellationToken).

SshSharpInfo: Build and identification information about the library.

SshSignRequest: One signature asked of an SshKeySigner: the algorithm, the data, and what the signature is for, so a signer can apply a policy (a key service that allows authentication only, say), log what it signs, or ask its user.

SshSignature: An SSH signature over a file or a message (OpenSSH's SSHSIG format, ssh-keygen -Y sign), as git uses for signed commits with gpg.format=ssh. Make one with SignAsync(SshPrivateKey, ReadOnlyMemory<byte>, string, string, CancellationToken) (any key, an agent's too), write it with ToString(), and read one with Parse(string).

SshTelemetry: The names SshSharp publishes diagnostics under. Subscribe to SourceName for traces (ActivitySource) and metrics (Meter), for example with OpenTelemetry: .AddSource(SshTelemetry.SourceName) and .AddMeter(SshTelemetry.SourceName). Nothing is recorded unless something listens, and no secrets (passwords, keys, command text) are ever recorded.

SshTerminalOptions: A pseudo-terminal request (RFC 4254 section 6.2).

Structs

SshHostKeyVerdict: A verifier's decision about a host key.

Enums

SshCertificateType: Whether an OpenSSH certificate certifies a user or a host.

SshFailureReason: Why an SSH operation failed.

SshKeyType: A key type to generate with Generate(SshKeyType, string?, int).

SshProxyType: The kind of proxy an SshProxy speaks.

SshSignaturePurpose: What a signature made with a private key is for (Purpose).

SshTerminalMode: Terminal mode opcodes (RFC 4254 section 8, and IUTF8 from RFC 8160), named as in POSIX termios.

Table of Contents

Namespace SshSharp

Classes

Structs

Enums