Thursday, July 26, 2007

Sysadmin joke...

I just thought I should create a new command. Every linux/unix sysadmin knows chmod, to change the permissions on a file, so I thought having a chmood. So for days like today I'd like to use my new command to be slightly more enthusiastic...

Yeah, I thought of that by doing a typo when I was trying to do a chmod...

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Friday, July 20, 2007

SSH tunnel tutorial


I created a tutorial with Wink that shows how to create an SSH tunnel. In this example, I'll be connecting, using ssh, to a host called Through the tunnel, I'll connect to "destinationhost" on port 8080. This can be usefull if destinationhost only allows connection on port 8080 from the server I'm connecting to using SSH.

To setup the tunnel, I simply open the SSH connection. When I want to access the web site located at, I simply enter "localhost:8081" in my browser.

Here is the wink tutorial.

An SSH tunnel can be used for many reasons:

  • Send or read your e-mails using an insecure protocol (POP3/IMAP/SMTP), through an encrypted tunnel
  • Encrypt your HTTP traffic while in an internet cafe, using a tunnel and a proxy (like squid)
  • Access a host that is behind a firewall (as long as you have access via SSH to another host behind this firewall
BTW, this may be against the policy of the organization, so please check with the sysadmin before doing that.