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ss command is a tool that is used for displaying network socket related information on a Linux system. The tool displays more detailed information that the netstat command which is used for displaying active socket connections.
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In this guide, we delve in and see how the ss command can be used to display varied socket connection information in Linux.
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1. Listing all Connections
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The basic ss command without any options simply lists all the connections regardless of the state they are in.
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$ ssrn
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2. Listing Listening and Non-listening Ports
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You can retrieve a list of both listening and non-listening ports using the -a option as shown below.
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$ ss -arn
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3. Listing Listening Sockets
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To display listening sockets only, use the -l flag as shown.
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$ ss -lrn
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4. List all TCP Connections
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To display all TCP connection, use the -t option as shown.
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$ ss -trn
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5. List all Listening TCP Connections
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To have a view of all the listening TCP socket connection use the -lt combination as shown.
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$ ss -ltrn
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6. List all UDP Connections
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To view all the UDP socket connections use the -ua option as shown.
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$ ss -uarn
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7. List all Listening UDP Connections
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To list listening UDP connections use the -lu option.
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$ ss -lurn
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8. Display PID (Process IDs) of Sockets
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To display the Process IDs related to socket connections, use the -p flag as shown.
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$ ss -prn
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9. Display Summary Statistics
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To list the summary statistics, use the -s option.
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$ ss -srn
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10. Display IPv4 and IPv6 Socket Connections
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If you are curious about the IPv4 socket connections use the -4 option.
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$ ss -4rn
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To display IPv6 connections, use the -6 option.
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$ ss -6rn
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11. Filter Connections by Port Number
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ss command also lets you filter socket port number or address number. For example, to display all socket connections with a destination or source port of ssh run the command.
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$ ss -at '( dport = :22 or sport = :22 )'rn
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Alternatively, you can run the command.
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$ ss -at '( dport = :ssh or sport = :ssh )'rn
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12. Check Man Pages for ss Command
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To get more insights into the ss command usage, check the man pages using the command.
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$ man ssrn
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Those are some of the commonly used options that are used with ss command. The command is considered more superior to netstat command and provide detailed information about network connections.
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