To be completely pedantic, a machine with no network services running is not necessarily completely secure. Most obviously, attacks can come in from compromised hosts you connect to. This is the most common attack vector these days thanks to malware on websites. Secondly, attacks can exploit vulnerabilities in the networking stack which can be tripped without a connection succeeding. I can think of two: the ping of death, and that nice information leak a while back where Linux was sending out Ethernet frames padded with random uninitialized rubbish from kernel memory (which could of course contain private data).
Copyright © 2018, Eklektix, Inc.
Comments and public postings are copyrighted by their creators.
Linux is a registered trademark of Linus Torvalds