How to find the active TCP connections and PIDs corresponding to them?

[tetelee]

Hi all,

I am programming on Linux middleware so I need to get a list of all active TCP connections. Is there any API to get such information? I know I can find the connections in /proc/net/tcp, but how to find the PIDs? Apparently ps or netstat command is not an option since it is a middleware. Any help will be appreciated!

Cheers
Tete

[Irithori]

Hi and welcome

As root

netstat -anp --ip

Also this might help

man netstat

[tetelee]

Hi and welcome

As root

netstat -anp --ip

Also this might help

man netstat

Thanks for the quick reply. But as I said, if it is a program, is it a little bit ugly to use system("netstat -any --ip") in the program? Is there any library or function to call to do the same job? Or actually I am new to linux programming so I don't really know how they usually do it? Just this system call? Thanks again!

[Irithori]

Sorry, missed that part.
I am not a dev, but from the look of the man page and also a quick strace, netstat actually parses /proc.

From the top of my head, I am not aware of a library or API, but maybe someone else here has an idea.

[Irithori]

There is a perl module
Linux::Proc::Net::TCP - search.cpan.org

Which language are you using?

[tetelee]

Which language are you using?

I am using C/C++. In fact in the /proc/net/tcp, I can only find the tcp transmission information as well as the UID. But my problem is how to trace which process or program is using which TCP connection? Thanks for your reply!

[Irithori]

hmm,
as you know C, a look into netstat´s code might provide more insight.
Index of /phil/net-tools/

Disclaimer:
This is GPL2 software, so be careful to actually re-implement, not copy, if your licence is not GPL2.