Monitor UDP port

[Sylvain CROUET]

Hello,

How would you monitor a UDP port on a server to check wether a process is listening to it, from the inside point of view (directly on the server) and the outside point of view (from another server).

[Florian Heigl (new acc)]

inside:
netstat -na | grep LISTEN or much better lsof.
outside:
nmap, or simply telnet.

[Steven E. Protter]

netstat -an | grep LISTEN | grep

SEP

[RAC_1]

On the server you can use netstat/lsof to monitor a port.

lsof -p udp:"port_number"
netstat -an|grep "port_number"

You can get lsof here.
http://hpux.connect.org.uk

From other server, you can try telneting to the port to check if it is listening or not.
telnet system "port_number"
You can also user some tools such as portscan, nport etc.

Anil

[Sylvain CROUET]

Well, lsof -p does not work for me:

toor@cexi01:/var/opt/OV/bin/OpC/monitor # lsof -p udp:"162"
lsof: illegal process ID: udp:162
lsof 4.55 (latest revision at ftp://vic.cc.purdue.edu/pub/tools/unix/lsof)
usage: [-?abChlnNoOPRstUvV] [-c c] [+|-d s] [+|-D D] [+|-f[cfgGn]]
[-F [f]] [-g [s]] [-i [i]] [-k k] [+|-L [l]] [-m m] [+|-M] [-o [o]] [-p s]
[+|-r [t]] [-S [t]] [-T [t]] [-u s] [+|-w] [--] [names]
Use the ``-h'' option to get more help information.
toor@cexi01:/var/opt/OV/bin/OpC/monitor #

[renarios]

Hi Crouet,

leave the quotes, i.e. lsof -p udp:162


cheerio,

Renarios

[Sylvain CROUET]

It does not work either. Same error.

[RAC_1 · Accepted solution]

It is -i option.

lsof -i tcp:23