[CentOS] ssh port forwarding

Thu Jul 12 17:32:39 UTC 2012
Joseph Spenner <joseph85750 at yahoo.com>

 From: Ski Dawg <centos at skidawg.org>
To: CentOS mailing list <centos at centos.org> 
Sent: Thursday, July 12, 2012 10:20 AM
Subject: [CentOS] ssh port forwarding
We are wanting to make mysql connections over an ssh tunnel.

In this case, lets say that hostA is our local machine, and hostB is the
Amazon EC2 instance. I have tried several different variations (that I have
found from google searching), including:
from hostA: ssh -L 22222:hostB:3306 user at hostB
from hostA: ssh -L 22222:localhost:3306 user at hostB
from hostA: ssh -L 22222:hostB:3306 user at localhost



  Depending on how the mysql is bound on hostB, either variation 1 or 2 should work. Variation 3 doesn't look very useful, since it implies hostA can already access tcp/3306 on hostB.
  After you build the port forwards, and open another terminal on HostA, and do:

$ telnet localhost 22222

What does it do?

Also, just to verify, if you're on hostB and do:

$ telnet localhost 3306

Does it 'connect' to a tcp port?