Netstat: melihat port yang aktif - Revision history

Onnowpurbo: /* Referensi */

2018-10-26T21:39:34Z

Referensi

← Older revision		Revision as of 21:39, 26 October 2018
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	* http://linuxers.org/howto/how-find-out-active-connections-or-which-ports-are-openlistening-linux		* http://linuxers.org/howto/how-find-out-active-connections-or-which-ports-are-openlistening-linux


			==Pranala Menarik==

			* [[netstat]]

Onnowpurbo at 21:39, 26 October 2018

2018-10-26T21:39:13Z

← Older revision		Revision as of 21:39, 26 October 2018
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			Melihat port yang di listen

			netstat -plnt # listen semua
			netstat -n -A inet # listen semua
			lsof -i # listen semua
			netstat -n -A inet -t # listen TCP
			netstat -n -A inet -u # listen UDP
			lsof -i4TCP # listen IPv4 TCP

	~~How to find out Active Connections or which Ports are open/listening on Linux~~		Contoh memfilter
	~~Written on May 18th, 2010 at 03:07 am by shredder12~~

	~~Sysadmin~~

	~~tux logo~~

	While managing a server or your home desktop, sometimes you might want to check out which ports are currently being used by which applications, what all TCP/UDP connections are active at the moment or other similar cases. There are two basic command line tools present in almost all the Linux/UNIX based systems - netstat and lsof, that might help you out with such queries.

	~~Before starting it would be good to know about these two commands.~~

	~~Netstat is used to display network connections, routing tables and a whole bunch of network and interface stats.~~
	lsof on the other hand is used to list out open files. So, if you want to find out what all files are currently open just run lsof. And since in Linux "Everything is a File", we can use lsof to print network connections too.

	~~Lets start learning by resolving common queries.~~
	~~How to display a list of open ports?~~

	~~This can be done using both netstat and lsof.~~

	~~[shredder12]$ netstat -n -A inet~~

	~~-n is used to display numeric addresses instead of trying to determine symbolic hostnames~~

	~~-A is used to define the address family we are concerned with. Here its internet connections on IPv4 network, so inet(user inet6 for IPv6 connections).~~

	~~[shredder12]$ lsof -i~~

	~~How to display a list of Active connections?~~

	~~In case you noticed the output of the command mentioned above, they actually show the active connections.~~

	~~[shredder12]$ netstat -n -A inet~~

	~~[shredder12]$ lsof -i~~

	~~How to display a list of listening ports?~~

	~~Use the --listen flag with netstat to get a list.~~

	~~[shredder12]$ netstat --listen -A inet~~

	~~How to display a list of active TCP or UDP connections?~~

	~~With netstat, we can use the flag -t to denote TCP connections only.~~

	~~[shredder12]$ netstat -n -A inet -t~~

	~~similarly, -u for UDP connections.~~

	~~The -i flag of lsof provides a lot of configurable options. Use the following command to filter out TCP connections.~~

	~~[shredder12]$ lsof -i4TCP~~

	~~Please note no space between i4 and TCP. This means TCP connections on IPv4 network. Similary one can use i6 for IPv6 and UDP for udp connections.~~
	~~How to find out all the ports being used by a single application or process using PID?~~

	~~With netstat option -p you can even list out the program a port/socket is associated with. So, lets run -p with our active connections command and grep the pid.~~

	~~[shredder12]$ netstat -A inet -n -p \| grep 1413~~

	~~You can find out the PID of a process using ps or pgrep.~~

	~~[shredder12]$ ps -e \| grep firefox~~

	~~[shredder12]$ pgrep firefox~~

	~~How to find out all the files being used by a program or application using PID?~~

	~~Since we are concerned with files, lsof comes into play here. Here the -p option used along with the PID to catch the files associated with that process.~~

	~~[shredder12]$ lsof -i4TCP -a -p 1413~~

	~~The -a flag is used to tell lsof to AND the result of all the options used.~~

	~~I hope this will help you out. If you want something to be added/modified/removed from here or have any other query just leave a comment~~


			netstat -plnt \| grep ':80' # web
			netstat -A inet -n -p \| grep 1413 # grep port socket
			ps -e \| grep firefox # grep firefox PID

Onnowpurbo: New page: Sumber: http://linuxers.org/howto/how-find-out-active-connections-or-which-ports-are-openlistening-linux How to find out Active Connections or which Ports are open/listening on Linux W...

2013-01-01T22:14:30Z

New page: Sumber: http://linuxers.org/howto/how-find-out-active-connections-or-which-ports-are-openlistening-linux How to find out Active Connections or which Ports are open/listening on Linux W...

New page

Sumber: http://linuxers.org/howto/how-find-out-active-connections-or-which-ports-are-openlistening-linux

How to find out Active Connections or which Ports are open/listening on Linux
Written on May 18th, 2010 at 03:07 am by shredder12

Sysadmin

tux logo

While managing a server or your home desktop, sometimes you might want to check out which ports are currently being used by which applications, what all TCP/UDP connections are active at the moment or other similar cases. There are two basic command line tools present in almost all the Linux/UNIX based systems - netstat and lsof, that might help you out with such queries.

Before starting it would be good to know about these two commands.

Netstat is used to display network connections, routing tables and a whole bunch of network and interface stats.
lsof on the other hand is used to list out open files. So, if you want to find out what all files are currently open just run lsof. And since in Linux "Everything is a File", we can use lsof to print network connections too.

Lets start learning by resolving common queries.
How to display a list of open ports?

This can be done using both netstat and lsof.

[shredder12]$ netstat -n -A inet

-n is used to display numeric addresses instead of trying to determine symbolic hostnames

-A is used to define the address family we are concerned with. Here its internet connections on IPv4 network, so inet(user inet6 for IPv6 connections).

[shredder12]$ lsof -i

How to display a list of Active connections?

In case you noticed the output of the command mentioned above, they actually show the active connections.

[shredder12]$ netstat -n -A inet

[shredder12]$ lsof -i

How to display a list of listening ports?

Use the --listen flag with netstat to get a list.

[shredder12]$ netstat --listen -A inet

How to display a list of active TCP or UDP connections?

With netstat, we can use the flag -t to denote TCP connections only.

[shredder12]$ netstat -n -A inet -t

similarly, -u for UDP connections.

The -i flag of lsof provides a lot of configurable options. Use the following command to filter out TCP connections.

[shredder12]$ lsof -i4TCP

Please note no space between i4 and TCP. This means TCP connections on IPv4 network. Similary one can use i6 for IPv6 and UDP for udp connections.
How to find out all the ports being used by a single application or process using PID?

With netstat option -p you can even list out the program a port/socket is associated with. So, lets run -p with our active connections command and grep the pid.

[shredder12]$ netstat -A inet -n -p | grep 1413

You can find out the PID of a process using ps or pgrep.

[shredder12]$ ps -e | grep firefox

[shredder12]$ pgrep firefox

How to find out all the files being used by a program or application using PID?

Since we are concerned with files, lsof comes into play here. Here the -p option used along with the PID to catch the files associated with that process.

[shredder12]$ lsof -i4TCP -a -p 1413

The -a flag is used to tell lsof to AND the result of all the options used.

I hope this will help you out. If you want something to be added/modified/removed from here or have any other query just leave a comment

==Referensi==

* http://linuxers.org/howto/how-find-out-active-connections-or-which-ports-are-openlistening-linux