command to know which port no is using by ssh or ftp or telnet service

singhjc · 08-18-2012, 07:46 AM

hello all,

i have a question which was asked to me by an interviewer the question is that.

how to know which port is using by ssh or telnet service through command i couldn't get it answer this question that why i came here , i really thankful for your correct reply.

camorri · 08-18-2012, 08:32 AM

You can find out what "well know ports" are at this site.

-->http://www.networksorcery.com/enp/pr...ports00000.htm

That does not tell you what ports are in use on any particular system though. For that you need a port scanner. In linux, nmap will scan a system. nmap is a command line tool. There is a gui front end called zenmap, that makes it easier for a terminal challenged person.

suicidaleggroll · 08-18-2012, 09:13 AM

You could also grep the config files for the services in question to see if they're set up to listen on any non-standard ports.

allend · 08-18-2012, 10:56 AM

Perhaps 'netstat -atpn' if you are interested in the local system?

chrism01 · 08-19-2012, 07:11 PM

A local on-machine list of the 'Well Known Ports' (& therefore defaults) is /etc/services