Ubuntu Tutorials - Herong's Tutorial Examples

∟Network Connection on Ubuntu

∟"netstat" - Display Network Statistics

This section provides a tutorial example on how to use 'netstat' command to display network statistics

"netstat" is a command line tool that allows you to see network statistics. Here are some examples on using the "netstat" command:

1. Display network traffic on all connections of all protocols: 

herong$ netstat -a 

Proto Recv-Q Send-Q Local Address      Foreign Address   State
tcp        0      0 0.0.0.0:51295      0.0.0.0:*         LISTEN
tcp        0      0 0.0.0.0:nfs        0.0.0.0:*         LISTEN
tcp        0      0 0.0.0.0:33833      0.0.0.0:*         LISTEN
tcp        0      0 localhost:5037     0.0.0.0:*         LISTEN
tcp        0      0 0.0.0.0:45139      0.0.0.0:*         LISTEN
tcp        0      0 localhost:domain   0.0.0.0:*         LISTEN
tcp        0      0 0.0.0.0:ssh        0.0.0.0:*         LISTEN
tcp        0      0 ubuntu:ssh         10.0.0.3:62780    ESTABLISHED
tcp        0      0 ubuntu:ssh         10.0.0.3:60186    ESTABLISHED
tcp6       0      0 [::]:nfs           [::]:*            LISTEN
tcp6       0      0 [::]:46791         [::]:*            LISTEN
...

2. Show TCP ports the local host is listening. Looks like I have so many network services that are running. I need to close some of them. 

herong$ netstat -lt

Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address        Foreign Address  State
tcp        0      0 0.0.0.0:sunrpc       0.0.0.0:*        LISTEN
tcp        0      0 0.0.0.0:imap         0.0.0.0:*        LISTEN
tcp        0      0 0.0.0.0:urd          0.0.0.0:*        LISTEN
tcp        0      0 0.0.0.0:ssh          0.0.0.0:*        LISTEN
tcp        0      0 localhost:ipp        0.0.0.0:*        LISTEN
tcp        0      0 0.0.0.0:smtp         0.0.0.0:*        LISTEN
tcp        0      0 0.0.0.0:pptp         0.0.0.0:*        LISTEN
tcp        0      0 0.0.0.0:imaps        0.0.0.0:*        LISTEN
tcp        0      0 0.0.0.0:pop3s        0.0.0.0:*        LISTEN
tcp        0      0 0.0.0.0:submission   0.0.0.0:*        LISTEN
tcp        0      0 0.0.0.0:pop3         0.0.0.0:*        LISTEN
tcp6       0      0 [::]:sunrpc          [::]:*           LISTEN
tcp6       0      0 [::]:imap            [::]:*           LISTEN
tcp6       0      0 [::]:http            [::]:*           LISTEN
tcp6       0      0 [::]:urd             [::]:*           LISTEN
tcp6       0      0 [::]:ftp             [::]:*           LISTEN
tcp6       0      0 [::]:ssh             [::]:*           LISTEN
tcp6       0      0 localhost:ipp        [::]:*           LISTEN
tcp6       0      0 [::]:smtp            [::]:*           LISTEN
tcp6       0      0 [::]:https           [::]:*           LISTEN
tcp6       0      0 [::]:imaps           [::]:*           LISTEN
tcp6       0      0 [::]:websm           [::]:*           LISTEN
tcp6       0      0 [::]:pop3s           [::]:*           LISTEN
tcp6       0      0 [::]:mysqlx          [::]:*           LISTEN
tcp6       0      0 [::]:mysql           [::]:*           LISTEN
tcp6       0      0 [::]:submission      [::]:*           LISTEN
tcp6       0      0 [::]:opsession-prxy  [::]:*           LISTEN
tcp6       0      0 [::]:pop3            [::]:*           LISTEN

3. Show UDP ports the local host is listening. I need to review each service and close some of them. 

herong$ netstat -lu
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address     Foreign Address  State
udp        0      0 localhost:domain  0.0.0.0:*
udp        0      0 0.0.0.0:bootps    0.0.0.0:*
udp        0      0 localhost:bootpc  0.0.0.0:*
udp        0      0 0.0.0.0:sunrpc    0.0.0.0:*
udp        0      0 localhost:323     0.0.0.0:*
udp        0      0 0.0.0.0:54488     0.0.0.0:*
udp        0      0 0.0.0.0:mdns      0.0.0.0:*
udp6       0      0 [::]:sunrpc       [::]:*
udp6       0      0 localhost:323     [::]:*
udp6       0      0 [::]:mdns         [::]:*
udp6       0      0 [::]:35424        [::]:*

4. Show TCP connections with their PIDs and program names: 

herong$ netstat -tp

Active Internet connections (w/o servers)
Proto Local Address         Foreign Address         PID/Program name
tcp   localhost:37124       hy.lcl:opsession-prxy   2906969/python3
tcp   localhost:imaps       192.168.1.7:64389       2906300/dovecot/imap
tcp   localhost:49482       192.168.1.:microsoft-ds -
tcp   localhost:urd         192.168.1.6:60248       2910580/smtpd
tcp   localhost:37122       hy.lcl:opsession-prxy   2906969/python3
tcp   localhost:ssh         192.168.1.4:59077       2906443/sshd: herong
tcp6  hy.lcl:opsession-prxy localhost:37124         5067/mysqld
tcp6  hy.lcl:opsession-prxy 192.168.1.7:65013       5067/mysqld

Table of Contents

 About This Book

 Introduction to Ubuntu Systems

 GNOME - Desktop Interface and Environment

 Shell - The Command-Line Interpreter

 Process Management

 Memory Management

 Files and Directories

 APT (Advanced Package Tool)

►Network Connection on Ubuntu

 Connect to Wi-Fi with GNOME Settings

 "traceroute" - Trace Route to Remote Host

 "ifconfig" - Trace Routes to Remote Host

 "route" - Manage Routing Table

►"netstat" - Display Network Statistics

 "lsof" - List of Open Files

 Internet Networking Tools

 SSH Protocol and ssh/scp Commands

 Administrative Tasks

 References

 Full Version in PDF/EPUB