16Jul
Wed2008 | Ports in Use Ruwan Linton
covers the process used to get an IANA-assigned port for Apache
Synapse.
I don't think I've ever bothered to talk to IANA for a port for
any of my applications.
- It's a hint. If someone is using your port -even if it's IANA
assigned- you have to be the one to deal with it. So your port must
always be a configurable option.
- A lot of ops teams like to change ports around, to add a bit of
obscurity to the game. There's no need to run SSH over port 22, for
example, and doing so on remotely visible machines just increases
your server load as machines around the world try and guess the
password for likely accounts.
- The real ports you have to avoid are those used by the trojans,
by Storm (port 7871 BTW) and other worms. Because the security
scanners will throw a wobbly when any scanned machine has those
ports open; its taken as a sign of being 0wned. And of course, the
malware authors never bother to go through IANA to pick a
port.
One thing that flexible applications can do is not require a
specific port. This is what the portmapper daemon can do.
It's a shame that this tool/binding protocol has fallen into
effective disuse.
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