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Man page:ssh

Usage

shell

ssh OPTIONS host COMMAND

Option	Description
`-i`	Specify an identity file.
`-t`	Open a tty even with there are COMMANDs.
`-X` `-Y`	Enable trusted X11 forwarding.
`-o`	Allow specifying options in the configuration file format.
`-f`	Go to background just before command execution.
`-N`	Do not execute a remote command. This is useful for just forwarding ports.
`-T`	Disable pseudo-terminal allocation.
`-M`	Places the ssh client into "master" mode for connection sharing.
`-S`	Specifies the location of a control socket for connection sharing.

Config Option	Values	Description
`StrictHostKeyChecking`	`yes/accept-new/no/ask`	Verify host fingerprint.

Step servers does not need any packages to be installed. The destination server needs a X11 package, as follows:

Distro	Package
Ubuntu 20.04	`dbus-x11`
CentOS 8	`xorg-x11-xauth`

When forwarding ports, keep in mind that a tunnel is created between the local (current) machine and the remote machine.

Forward requests from local:123 to A:456. (local:123 → A:456)

shell

ssh -L 123:localhost:456 A

Forward requests from B:456 to local:123. (local:123 ← B:456)

shell

ssh -R 456:localhost:123 B

Creates a SOCKS server that will forward connections through it. Use as a proxy server.

shell

ssh -D 1080 A

Port-forward a SSH connection in the background:

shell

ssh -fNTMS my-socket -D 1070 dest
ssh -S my-socket -O check dest
ssh -S my-socket -O exit dest