awtop

A really simple cross-platform network/process monitor. lsof -i isn't that good :P

how to install?

It's tested on OS X with Python 2.7 and uses a third-party psutil module. You can install it via either pip or easy_install:

pip install psutil

how to use?

You can search for the nasty process that's connecting to some site just like that:

$ python awtop.py -s "*github*"
 41398 | + Google Chrome
       | |-- ESTABLISHED     | ip1b-lb3-prd.iad.github.com:443
       | |-- ESTABLISHED     | ip1b-lb3-prd.iad.github.com:443
 54981 | + ssh
       | |-- ESTABLISHED     | ip1b-lb3-prd.iad.github.com:22
 54985 | + ssh
       | |-- ESTABLISHED     | ip1b-lb3-prd.iad.github.com:22

By default, it shows connections of the proccesses that user has permissions to access to. If you have problem with that, feel free to run it with sudo.

It shows the least bit of information - for example, it doesn't bother to show you the source IP. Or connections marked as CLOSE. Or localhost <-> localhost connections.

There's some options, though, to satisfy your curiosity. Feel free to run it with --help to see something like that:

  -n          don't resolve hostnames
  -l          show connections that go to localhost
  -p          show incoming hostnames (it doesn't filter the connection list;
              just suppresses a bit of output)
  -c          show closed connections
  -s SEARCH   search in outgoing hosts by wildcard