Ubuntu and firewall [LWN.net]

Ubuntu and firewall

Posted Oct 5, 2006 9:41 UTC (Thu) by ayeomans (subscriber, #1848)
In reply to: Ubuntu and firewall by drag
Parent article: Mark Shuttleworth interview (Linux Format)

Not sure if this is still true. It ceertainly used to be the case that you could turn off all listening services. But they are coming back into fashion. My stock Ubuntu system is listening on four ip ports by default, three to do with printing, even though I don't have a printer connected:

4351/tcp python /usr/sbin/hpssd
4325/tcp /usr/sbin/hpiod
23974/tcp /usr/sbin/cupsd
3497/udp dhclient3 (for eth0)

If it wasn't for the fact that I'm behind a hardware firewall, I'd feel a bit uneasy about advertising these on the Internet. So a firewall that restricts access to local subnet would seem a good idea.

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Ubuntu and firewall

Posted Oct 6, 2006 3:19 UTC (Fri) by nlucas (subscriber, #33793) [Link]

You forgot to include the addresses they are binding to.

Except for dhclient3 (which obviously is using an external connection to your dhcp server) they are all bound to localhost (unless you configured them differently).