Finding which ports are in use on Linux System.

Hi there,

I'd greatly appreciate if someone could please
help me with a problem. I am using a RH Linux
system on which I want to find which ports are
already in use. This I want to do in a program
rather than using some command like lsof. Is
there any API using which I can achieve this.

Thanks,
Bhavin.

On 18 Apr 2004 07:59:29 -0700, B. Gandhi <(E-Mail Removed)> wrote:
> Hi there,
>
> I'd greatly appreciate if someone could please
> help me with a problem. I am using a RH Linux
> system on which I want to find which ports are
> already in use. This I want to do in a program
> rather than using some command like lsof. Is
> there any API using which I can achieve this.

What kind of ports (i/o ports, network ports, etc.)?

You will likely find that info in /proc. For example network ports in use
can be found in tcp, tcp6, udp and udp6 files in /proc/net/

--
David Efflandt - All spam ignored http://www.de-srv.com/

(E-Mail Removed) (David Efflandt) wrote in message news:<(E-Mail Removed)>...
> On 18 Apr 2004 07:59:29 -0700, B. Gandhi <(E-Mail Removed)> wrote:
> > Hi there,
> >
> > I'd greatly appreciate if someone could please
> > help me with a problem. I am using a RH Linux
> > system on which I want to find which ports are
> > already in use. This I want to do in a program
> > rather than using some command like lsof. Is
> > there any API using which I can achieve this.
>
> What kind of ports (i/o ports, network ports, etc.)?
>
> You will likely find that info in /proc. For example network ports in use
> can be found in tcp, tcp6, udp and udp6 files in /proc/net/

I apologize for being vague, yeah, I meant network
ports. Thanks.

B. Gandhi wrote:

> I'd greatly appreciate if someone could please
> help me with a problem. I am using a RH Linux
> system on which I want to find which ports are
> already in use. This I want to do in a program
> rather than using some command like lsof. Is
> there any API using which I can achieve this.

netstat -nlp

-n numeric
-l listen
-p give me the process number (only usefule if you are root)

in a programm.. you can grep the output of netstat, or get the source of
netstat and look how it manages self to get the ouput.
( with debian a "apt-get source net-tools" should give you the
source/example code)

--
mfG Florian

Use netstat to find port information,

#netstat -a | less

x86

Gentoo Linux 1.4 (2.6.5-mm1) / FreeBSD Unix 4.9 - Pentium M 1.40GHz -
512 MB - 40 GB - 14" - 4.5-4.9 lbs - CD-RW/DVD-ROM - Intel
PRO/1000 Gigabit Ethernet - Intel PRO/Wireless Network Connection
802.11b

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On Sun, 18 Apr 2004 07:59:29 -0700, B. Gandhi wrote:

> I'd greatly appreciate if someone could please
> help me with a problem. I am using a RH Linux
> system on which I want to find which ports are
> already in use. This I want to do in a program
> rather than using some command like lsof. Is
> there any API using which I can achieve this.

Hi B. Gandhi,
give netstat -vatnp
and nmap a try