When your Linux server seems to have network issues, you should be able to log in via VNC console to troubleshoot the issue

Mostly used Linux network commands:

ip addr show # Displays the addresses for every link configured on the system. Locate the eth0 link, which connects the host to the wider network on most systems. The inet field displays the Ipv4 address. It replaces the old ifconfig command

   ip addr show

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host
       valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP group default qlen 1000
    link/ether f2:3c:93:60:50:30 brd ff:ff:ff:ff:ff:ff
    inet 178.00.000.000/24 brd 178.00.000.255 scope global eth0
       valid_lft forever preferred_lft forever
    inet6 2a01:7e00::f03c::5030/64 scope global dynamic mngtmpaddr noprefixroute
       valid_lft 5155sec preferred_lft 1555sec
    inet6 fe80::f03c::5030/64 scope link
       valid_lft forever preferred_lft forever
   ifconfig #only displays enabled interfaces. 

ping # Test network connectivity to a remote host

 ping google.com
PING google.com (200.0.000.000) 56(84) bytes of data.
64 bytes from par.net (200.0.000.000): icmp_seq=1 ttl=117 time=21.4 ms
64 bytes from par.net (200.0.000.000): icmp_seq=2 ttl=117 time=23.6 ms


mtr # combines the functionality of traceroute and ping to provide continuous traceroute-like output for network diagnostics. It sends ICMP ECHO requests to each router on the path to a destination host, showing both the round-trip time and packet loss percentage at each hop. 1

Guide How To Use MTR 

  mtr google.com
My traceroute  [v0.92]
hostname (0.0.0.0)                                  Thu Jun 21 12:00:00 2024
Keys:  Help   Display mode   Restart statistics   Order of fields   quit
                                             Packets               Pings
 Host                                      Loss%   Snt   Last   Avg  Best  Wrst StDev
 1. router1                                 0.0%     5    1.0   1.2   0.9   1.5   0.2
 2. isp-router                              0.0%     5    9.1  10.2   8.3  12.5   1.2
 3. destination-router                       0.0%     5   20.5  15.9  14.3  20.5   2.0
 4. google.com                               0.0%     5   21.7  18.3  17.1  21.7   1.8

iperf # widely used tool for network performance measurement and tuning. Iperf has client and server functionality, it allows you to measure various parameters of a network connection, such as bandwidth, latency, and packet loss.

Guide How To Use IPERF

netstat # Display all the active network connections, routing tables, and interface statistics on your Linux system.

This helps in understanding what applications or daemons are running and potentially causing issues, crucial for troubleshooting port conflicts or unauthorized services running on unexpected ports.

Useful in verifying firewall rules and monitoring for unauthorized services or suspicious network activity

 netstat -tulpn #shows all programs listening for connections, along with their details like ports and IDs, using numbers instead of names.

Proto Recv-Q Send-Q Local Address           Foreign Address         State       PID/Program name    
tcp        0      0 127.0.0.53:53           0.0.0.0:*               LISTEN      -                   
tcp        0      0 127.0.0.1:631           0.0.0.0:*               LISTEN      -                   
tcp        0      0 127.0.0.1:46565         0.0.0.0:*               LISTEN      1616/eidLvUIServer  
tcp6       0      0 :::45623                :::*                    LISTEN      71127/AppRun.wrappe 
tcp6       0      0 :::5061                 :::*                    LISTEN      71127/AppRun.wrappe 
tcp6       0      0 ::1:631                 :::*                    LISTEN      -                   
tcp6       0      0 :::1716                 :::*                    LISTEN      1614/kdeconnectd    
udp        0      0 0.0.0.0:52881           0.0.0.0:*                           -                
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