Network Diagnostics

When troubleshooting network issues, you can use diagnostic tools like ping, traceroute, netstat, and ss to check connectivity, trace routes, and inspect active network connections.

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1. ping - Check Network Connectivity

The ping command tests connectivity between your system and another device by sending ICMP echo requests.

1. Check if a host is reachable

    ping google.com
   

   

2. Limit the number of packets sent (e.g., 5 packets)

    ping -c 5 google.com
   

   

3. Set packet size (e.g., 100 bytes)

    ping -s 100 google.com
   

   

4. Set time interval between pings (e.g., 2 seconds)

    ping -i 2 google.com
   

   

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2. traceroute - Trace the Path of a Packet

The traceroute command shows the route packets take to reach a destination.

1. To display a list of routers between your computer and Google's server.

    traceroute google.com
   

   

Understanding traceroute Output

Example output:

nginxCopyEdittraceroute to google.com (142.250.183.206), 30 hops max, 60 byte packets
 1  192.168.1.1 (192.168.1.1)  1.23 ms  1.12 ms  1.10 ms
 2  10.0.0.1 (10.0.0.1)  5.89 ms  5.76 ms  5.80 ms
 3  203.0.113.1 (203.0.113.1)  12.34 ms  12.40 ms  12.50 ms
 4  * * *
 5  142.250.183.206 (google.com)  25.67 ms  25.75 ms  25.80 ms

Explanation:

• Each line represents a hop (a router in the path).

• 192.168.1.1 is the first router (local network gateway).

• 10.0.0.1 is the second router.

• 203.0.113.1 is another router in the path.

• * * * means a router is not responding.

• The final destination (google.com) is reached in 5 hops.

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3. netstat (Deprecated, Use ss Instead)

The netstat command displays active network connections, routing tables, and network statistics. It is now replaced by ss.

Show all active network connections

 netstat -a

Options:

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4. ss (Replacement for netstat)

The ss command is a faster and more powerful alternative to netstat, providing detailed information about socket connections.

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