If you have routing to the IP, then it's just a matter of: $ telnet <ip> <port> If you don't have routing, then you'll need to arrange it somehow. With the

If you have routing to the IP, then it's just a matter of: $ telnet <ip> <port> If you don't have routing, then you'll need to arrange it somehow. With the example addresses you gave, you could do it by being on your immediate upstream network and then running: $ ip route add 192.168.1.123/24 via 123.45.67.89 $ telnet 192.168.1.123 <port>