Linux: Find Out What Is Using TCP Port 80

H

ow do I find out what is listing or using tcp port number 80 on Linux based systems using command line options?

 

You can use any one of the following command to find out what is using tcp or udp port number 80 on Linux operating systems:

netstat – a command-line tool that displays network connections, routing tables, and a number of network interface statistics.

fuser – a command line tool to identify processes using files or sockets.

lsof – a command line tool to list open files under Linux / UNIX to report a list of all open files and the processes that opened them.

/proc/$pid/ file system – Under Linux /proc includes a directory for each running process (including kernel processes) at /proc/PID, containing information about that process, notably including the processes name that opened port.

Examples

Open a terminal and then type the following command as root user:

netstat command find out what is using port 80

Type the following command

# netstat -tulpn | grep :80

 

OR pass the –color option to grep command as follows:

# netstat -tulpn | grep –color :80

 

Sample outputs:

tcp        0      0 0.0.0.0:80                  0.0.0.0:*                   LISTEN      1215/nginx

Where,

0 0.0.0.0:80 – Source IP:Port

1215/nginx – PID/Process name

The tcp port 80 is opened and used by nginx web server. Type the following command to find out more about nginx:

whatis nginx

whereis nginx

Note: You may need to install lsof and fuser command.

Use /proc/$pid/exec file find out what is using port 80

First, find out the processes PID that opened tcp port 90, enter:

# fuser 80/tcp

 

Sample outputs:

80/tcp:              12161 21776 25250 25393

Finally, find out process name associated with PID # 3813, enter:

# ls -l /proc/12161/exe

 

Sample outputs:

lrwxrwxrwx. 1 root root 0 Aug  9 13:28 /proc/12161/exe -> /usr/sbin/lighttpd

Find out more about lighttpd:

man lighttpd

whatis lighttpd

whereis lighttpd

Sample outputs:

lighttpd             (8)  – a fast, secure and flexible web server

lighttpd: /usr/sbin/lighttpd /usr/lib64/lighttpd /usr/share/man/man8/lighttpd.8.gz

You can use package manager to dig into lighttpd:

# rpm -qa | grep lighttpd

 

Sample outputs:

lighttpd-1.4.32-1.el6.x86_64

To find out more about lighttpd-1.4.32-1.el6.x86_64 package, type:

# yum info lighttpd-1.4.32-1.el6.x86_64

 

Sample outputs:

Loaded plugins: auto-update-debuginfo, protectbase, rhnplugin, security

This system is receiving updates from RHN Classic or RHN Satellite.

0 packages excluded due to repository protections

Installed Packages

Name        : lighttpd

Arch        : x86_64

Version     : 1.4.32

Release     : 1.el6

Size        : 664 k

Repo        : installed

Summary     : A web server more optimized for speed-critical environments.

URL         : http://lighttpd.net/

License     : Revised BSD

Description : It is a secure and fast web server a very low memory footprint compared

: to other webservers and takes care of cpu-load.

OR use rpm command:

# rpm -qi lighttpd

 

Sample outputs:

Name        : lighttpd                     Relocations: (not relocatable)

Version     : 1.4.32                            Vendor: nixCraft

Release     : 1.el6                         Build Date: Sun 03 Feb 2013 03:22:08 AM CST

Install Date: Mon 04 Feb 2013 04:44:26 AM CST      Build Host: rhel6.nixcraft.net.in

Group       : System Environment/Daemons    Source RPM: lighttpd-1.4.32-1.el6.src.rpm

Size        : 680402                           License: Revised BSD

Signature   : (none)

URL         : http://lighttpd.net/

Summary     : A web server more optimized for speed-critical environments.

Description :

It is a secure and fast web server a very low memory footprint compared

to other webservers and takes care of cpu-load.

Debian / Ubuntu Linux user can use the following commands:

# dpkg –list | grep lighttpd

# apt-cache search lighttpd

# apt-cache show lighttpd

 

Sample outputs from the last command:

Package: lighttpd

Priority: optional

Section: universe/web

Installed-Size: 841

Maintainer: Ubuntu Developers

Original-Maintainer: Debian lighttpd maintainers

Architecture: amd64

Version: 1.4.28-2ubuntu4

Provides: httpd, httpd-cgi

Depends: libattr1 (>= 1:2.4.46-5), libbz2-1.0, libc6 (>= 2.4), libgamin0 | libfam0, libldap-2.4-2 (>= 2.4.7), libpcre3 (>= 8.10), libssl1.0.0 (>= 1.0.0), zlib1g (>= 1:1.1.4), lsb-base (>= 3.2-14), mime-support, libterm-readline-perl-perl

Recommends: spawn-fcgi

Suggests: openssl, rrdtool, apache2-utils, ufw

Conflicts: cherokee (<= 0.6.1-1)

Filename: pool/universe/l/lighttpd/lighttpd_1.4.28-2ubuntu4_amd64.deb

Size: 279838

MD5sum: 65aedfd0e0ab6d3ee28e7b394567ed22

SHA1: 34a9156fa3d23635eb24efb436de585c0594f046

SHA256: 751d6f8309d249740d7aab240a74b6bae713e524cf6815544b6cdbb6107fded2

Description-en: A fast webserver with minimal memory footprint

lighttpd is a small webserver and fast webserver developed with

security in mind and a lot of features.

It has support for

* CGI, FastCGI and SSI

* virtual hosts

* URL rewriting

* authentication (plain files, htpasswd, ldap)

* transparent content compression

* conditional configuration

and configuration is straight-forward and easy.

Homepage: http://www.lighttpd.net

Description-md5: 267ee2989b526d8253e822e7d8244ccd

Bugs: https://bugs.launchpad.net/ubuntu/+filebug

Origin: Ubuntu

lsof command find out what is using port 80

Type the following command

# lsof -i :80 | grep LISTEN

 

Sample outputs:

apache2   1607     root    3u  IPv4   6472      0t0  TCP *:www (LISTEN)

apache2   1616 www-data    3u  IPv4   6472      0t0  TCP *:www (LISTEN)

apache2   1617 www-data    3u  IPv4   6472      0t0  TCP *:www (LISTEN)

See also

Linux: Find Out Which Process Is Listening Upon a Port

ss: Display Linux TCP / UDP Network and Socket Information

See man pages for more info lsof(8),fuser(1),proc(5),netstat(8),ss(8)

 

 

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