If it doesn’t exist, which is the default, we’ll have to create a new one. We can use the global ssh client config file (located on /etc/ssh/ssh_config or/etc/openssh/ssh_config) or use our user’s specific configuration file that is located at ~/.ssh/config. That’s why one of the most lovely features of ssh is allowing any command-line parameters in the config files. If disabled, other hosts on the SSH server network might use it.

X11UseLocalhost: Forces the X11 forwarding to be only allowed from the SSH server host loopback address.

X11Forwarding: Specifies whether X11 forwarding is allowed.

PermitTunnel: Specifies whether tun device forwarding is allowed.PermitOpen: Specifies the address and ports a TCP forwarding may point to.It provides more fine control if we enable GatewayPorts. PermitListen: Specifies the addresses and ports that can be bound to allow port-forwarding to clients.By default, only the hosts running the SSH server can use reverse tunnels.

GatewayPorts: Allows other hosts to use the ports forwarded to a client (reverse tunnels).Override, if enabled, all other related configurations options DisableForwarding: Disables all kinds of forwarding.It enables single TCP port forwards and socks proxying AllowTcpForwarding: Allows TCP port forwarding.AllowStreamLocalForwarding: Allows Unix domain sockets to be forwarded.Its location varies a little but is usually on /etc/ssh or /etc/openssh. The enablement of sshd, the daemon that serves ssh sessions, is done by editing the sshd_configfile.

Persistent ssh tunnel windows