Someone at work pointed out a cool utility called tsocks.
tsocks allows non-SOCKS-aware applications (e.g.: telnet, ssh, ftp, etc.) to use SOCKS without any modification. It does this by intercepting the calls that applications make (i.e.: through
LD_PRELOAD) to establish network connections and negotating them through a SOCKS server as necessary.
Installing it on a Debian-based system is as easy as:
$ sudo apt-get install tsocks
I then edited my
/etc/tsocks.conf file to have this:
local = 192.168.1.0/255.255.255.0 local = 10.0.0.0/255.0.0.0 server = 127.0.0.1 server_type = 4 server_port = 1080
The last part is the most important part and is basically telling tsocks that it’s going to proxy all of my connections through a SOCKS 4 proxy at localhost:1080 (this SOCKS proxy comes from the fact that I have a “
DynamicForward 1080” line in my
~/.ssh/config for the ssh proxy that I use to connect to work).
Then I can access machines behind the corporate firewall by invoking tsocks in “one-off” fashion like this:
$ tsocks ssh somehost.firewalleddomain.net
or if typing “
tsocks” in front of each of your commands is too much trouble, tsocks can be turned on and off semi-permanently so you can do stuff like this:
$ source /usr/bin/tsocks on $ ssh host1.firewalleddomain.net $ ssh host2.firewalleddomain.net $ source /usr/bin/tsocks off
Neat concept. Interesting use of