ssh commands

i2p tunnel

creating a tunnel to a server running i2p

-fTN

run in the background, no tty allocation and no remote command, respectively

-L

local port forwarding, i.e. the requests to the local port (first number) on localhost (this machine) are forwarded to the remote port (second number) on my i2p box.

4444, 7070

the ports needed for i2p. 4444 is the proxy port and 7070 is the router console port

box

a placeholder for the name of the server

reverse tunnel

creating a reverse ssh tunnel from a firewalled host to a server

-NT

do not execute a remote command and do not allocate a tty

-o ServerAliveInterval=60

send a packet every 60 seconds to keep the connection alive – useful for long-lived connections

-R

reverse port forwarding, i.e. the requests to the remote port (first number) on the server are forwarded to the local port (second number) on the client

11111

the port on the server

localhost:22

the port on the client (ssh)

box

the 'outside' server

then, ssh -p 11111 user@localhost will connect to the firewalled host from the server.

jump hosts

if the server is used as a jump host, then ssh -J user@jumphost user@finalhost will connect to the final host through the jump host.

e.g. used with the previous command, ssh -J user@server -p 11111 user@localhost will connect to the firewalled host from the client via the server as the jump host.