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James
Asked: 2013-08-18 12:33:13 +0800 CST

List all internet connections

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I'd like to know all the connections my system is making to the internet. I tried netstat but that shows a lot of connections - all of which aren't applicable I think. Can it be displayed like top does for processes ?

I'm a little security conscious and would like to know all the incoming and outgoing connections happening on my system.

internet

2 Answers

  1. Using netstat

    netstat by itself monitors all major protocols including TCP and UDP on every port.

    If you want to display TCP and UDP connections:

       netstat -t -u

    If you want to display that continously:

       netstat -t -u -c

    Similar to top:

    1. nethogs - shows a list of the top processes that use bandwidth

    2. jnettop - shows list of top connections

    3. iftop - shows list of top connections with bandwidth bars

    GUI Interface (just in case):

    1. Ntop

    2. Netactview

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  2. You may try ss as well, it's more advanced than netstat.

    • $ ss --tcp -all

    List all TCP connections (including those with non-established state, e.g. SYN-SENT, LISTEN, and TIME-WAIT). Read more about TCP states transition in RFC793.

    State                    Recv-Q               Send-Q                             Local Address:Port                                 Peer Address:Port     
LISTEN                   0                    4096                                   127.0.0.1:5672                                      0.0.0.0:*    
ESTAB                    0                    0                                    192.168.1.4:57310                               35.157.63.229:443  
ESTAB                    0                    0                                      127.0.0.1:43764                                   127.0.0.1:8080 
CLOSE-WAIT               1                    0                                    192.168.1.4:34554                              142.250.186.33:443  
CLOSE-WAIT               1                    0                                    192.168.1.4:34564                              142.250.186.33:443
    • $ ss --tcp --all --processes

    Include information about the owner process of the connections (e.g., process name and PID)

    • $ ss state established '( dport = :ssh or sport = :ssh )'

    Display all established SSH connections.

    • $ ss --options state fin-wait-1 '( sport = :https )' dst 193.233.7/24

    List all the TCP sockets in state FIN-WAIT-1 for network 193.233.7/24 and look at their timers with --options, which shows timer information.

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