Sunday, 19 May 2013

No idea what is listening on port 80 in OS X

No idea what is listening on port 80 in OS X

I'm on OSX Mountain Lion 10.8.3, and I've freshly rebooted my Mac.
I want to start a service (like Apache on port 80), but there is already something going on with port 80:
telnet localhost 80

Trying ::1...
Connected to localhost.
Escape character is '^]'.
Wait, I hear you say, you can find that with lsof or netstat. Except there is nothing there
netstat -an | grep LISTEN | grep '\.80'

*comes back blank*

lsof -i :80 | grep LISTEN

*comes back blank
So from what I know about unix systems, I figure this must be a packet forwarding rule then? I.e. packets are being forwarded from inbound port 80 to something else, which is listening on that service.
ipfw show

65535 0 0 allow ip from any to any
Hmm, nothing unusual there
pfctl -s nat

No ALTQ support in kernel
ALTQ related functions disabled
Nothing unusual there
My question is, how can I display any packet forwarding rules... On Linux I might just do iptables -L -t NAT, or iptables -L. Or alternatively, can any OSX experts help me diagnose this problem?

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