Determine what service listening on port

[Steve Phillips]

Romeo Theriault wrote:
> The -sV option on nmap would give you service version information. You 
> might
> also want to try connecting to the ports with telnet to see what they might
> show.

I find "lsof | grep <port>" tends to use (obviously without < and > ) 
but usually takes a little interpretation (i.e - look for UDP: <port>, 
not the other random things that will show up in such a generalised 
grep), lsof will show the process that has the port open, past that, you 
can trace back PIDs and PPID's to find the process parent - as is 
usually needed when dealing with java applications etc.

trying to use 'telnet' to connect to a UDP port however will be rather 
fruitless, as was the "LISTEN" suggestion (UDP services show as "Idle" 
not LISTENING)

good luck :-)

-- 
Steve.

> 
> On 7/13/07, joseph tacuyan <joseph.mailboxlist at gmail.com> wrote:
>>
>> how about nmapping it?
>>
>> On 7/13/07, redhat at buglecreek.com <redhat at buglecreek.com> wrote:
>> >
>> > I have a RHEL ES3 server that has three listening udp ports open.  I'm
>> > having a hard time trying to determine what service opened them up.  
>> The
>> > ports are udp 1020,1022,1023.  I have tried to following: "netstat 
>> -lp",
>> > the PID/Program name column just shows a -,  "fuser -n udp 1020",
>> > nothing returned, lsof -i :1020. nothing returned.  I have shut down a
>> > few services in an attempt to discover who opened the ports, but no
>> > luck.  Anything I may have forgotten?
>> >
>> > Thanks
>> >
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