Linux: Find Out What Is Using TCP Port 80 (2024)

How 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:

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

Tutorial details
Difficulty level	Easy
Root privileges	No
Requirements	None
Est. reading time	3 minutes

2. fuser – a command line tool to identify processes using files or sockets.
3. 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.
4. /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,

1. 0 0.0.0.0:80 – Source IP:Port
2. 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 nginxwhereis 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 lighttpdwhatis lighttpdwhereis lighttpd

Sample outputs:

lighttpd (8) - a fast, secure and flexible web serverlighttpd: /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, securityThis system is receiving updates from RHN Classic or RHN Satellite.0 packages excluded due to repository protectionsInstalled PackagesName : lighttpdArch : x86_64Version : 1.4.32Release : 1.el6Size : 664 kRepo : installedSummary : A web server more optimized for speed-critical environments.URL : http://lighttpd.net/License : Revised BSDDescription : 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: nixCraftRelease : 1.el6 Build Date: Sun 03 Feb 2013 03:22:08 AM CSTInstall Date: Mon 04 Feb 2013 04:44:26 AM CST Build Host: rhel6.nixcraft.net.inGroup : System Environment/Daemons Source RPM: lighttpd-1.4.32-1.el6.src.rpmSize : 680402 License: Revised BSDSignature : (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 comparedto 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: lighttpdPriority: optionalSection: universe/webInstalled-Size: 841Maintainer: Ubuntu Developers Original-Maintainer: Debian lighttpd maintainers Architecture: amd64Version: 1.4.28-2ubuntu4Provides: httpd, httpd-cgiDepends: 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-perlRecommends: spawn-fcgiSuggests: openssl, rrdtool, apache2-utils, ufwConflicts: cherokee (<= 0.6.1-1)Filename: pool/universe/l/lighttpd/lighttpd_1.4.28-2ubuntu4_amd64.debSize: 279838MD5sum: 65aedfd0e0ab6d3ee28e7b394567ed22SHA1: 34a9156fa3d23635eb24efb436de585c0594f046SHA256: 751d6f8309d249740d7aab240a74b6bae713e524cf6815544b6cdbb6107fded2Description-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.netDescription-md5: 267ee2989b526d8253e822e7d8244ccdBugs: https://bugs.launchpad.net/ubuntu/+filebugOrigin: 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