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# on b's 192.168.0.2 interface, listen for incoming connections on port 2525
# and forward them to c's localhost on port 25 (assumes b has an interface with
# an ip address of 192.168.0.2 and c is listening for ssh connections on port
# 25).
user@b$ ssh -L 192.168.0.2:2525:localhost:25 user@c
# on a, ssh to b's 192.168.0.2 interface on port 2525, this will be forwarded
# to c on port 25.
user@a$ ssh -p 2525 [email protected]