SSH config directives reference

Complete reference for ~/.ssh/config directives including Host, HostName, Port, IdentityFile, ProxyJump, and ForwardAgent.

Complete reference for SSH client configuration directives in ~/.ssh/config covering connection, authentication, tunneling, and proxy settings.

SSH Connection Directives

Directive	SSH behavior	Default	Example
`Host`	SSH defines a named alias that matches against the hostname argument; supports wildcards ( `*`, `?`)	Required	`Host production`
`HostName`	SSH connects to this hostname or IP address when the alias matches	Alias name	`HostName 203.0.113.50`
`Port`	SSH connects to this TCP port on the remote server	`22`	`Port 2222`
`User`	SSH authenticates as this username on the remote server	Local username	`User admin`
`AddressFamily`	SSH uses IPv4 only ( `inet`), IPv6 only ( `inet6`), or both ( `any`)	`any`	`AddressFamily inet`

Directive	SSH behavior	Default	Example
`IdentityFile`	SSH uses this private key file for public key authentication	`~/.ssh/id_rsa`, `~/.ssh/id_ed25519`	`IdentityFile ~/.ssh/prod_key`
`IdentitiesOnly`	SSH offers only the keys specified by `IdentityFile`, ignoring the agent's key list	`no`	`IdentitiesOnly yes`
`PreferredAuthentications`	SSH attempts authentication methods in this order	`publickey,keyboard-interactive,password`	`PreferredAuthentications publickey`
`PasswordAuthentication`	SSH allows password authentication to the server	`yes`	`PasswordAuthentication no`

Directive	SSH behavior	Default	Example
`LocalForward`	SSH binds a local port and forwards traffic to a remote destination through the SSH tunnel	None	`LocalForward 3306 localhost:3306`
`RemoteForward`	SSH binds a port on the remote server and forwards traffic back to the local machine	None	`RemoteForward 8080 localhost:80`
`DynamicForward`	SSH creates a local SOCKS5 proxy that routes all traffic through the SSH connection	None	`DynamicForward 1080`
`ProxyJump`	SSH routes the connection through an intermediate SSH host (bastion/jump host) before reaching the target	None	`ProxyJump bastion`
`ForwardAgent`	SSH forwards the local SSH agent to the remote server, allowing onward SSH connections using local keys	`no`	`ForwardAgent yes`

Directive	SSH behavior	Default	Example
`ServerAliveInterval`	SSH sends a keepalive message every N seconds to prevent idle connection drops	`0` (disabled)	`ServerAliveInterval 60`
`ServerAliveCountMax`	SSH disconnects after this many unanswered keepalive messages	`3`	`ServerAliveCountMax 5`
`ConnectTimeout`	SSH limits the TCP connection phase to this many seconds	System default	`ConnectTimeout 10`
`Compression`	SSH enables zlib compression on the connection — useful for slow links	`no`	`Compression yes`
`LogLevel`	SSH sets the verbosity of client-side logging	`INFO`	`LogLevel DEBUG`