Connectivity is a crucial aspect of any networked environment, including Linux systems. Ensuring that your Linux machine can communicate with other devices on the network, access the internet, and resolve domain names is fundamental for both personal and enterprise use. This article explores various methods and tools available in Linux to check and troubleshoot network connectivity. We will cover basic commands such as ping, ifconfig, and netstat, as well as more advanced tools like traceroute and nmap.

Examples:

1. Checking Network Interface Configuration:

   The ifconfig command is used to display or configure network interfaces. To check the current configuration of your network interfaces, you can use:

   ifconfig

   This will display information about all network interfaces, including IP addresses, subnet masks, and MAC addresses.

2. Testing Connectivity with Ping:

   The ping command is used to test the reachability of a host on an IP network. For example, to check if you can reach Google's DNS server, you can use:

   ping 8.8.8.8

   This will send ICMP echo requests to the specified IP address and display the response time.

3. Displaying Routing Information:

   The netstat command can be used to display network connections, routing tables, interface statistics, masquerade connections, and multicast memberships. To display the routing table, you can use:

   netstat -r

   Alternatively, you can use the route command:

   route -n

4. Tracing Network Path with Traceroute:

   The traceroute command is used to display the route packets take to a network host. To trace the route to Google's DNS server, you can use:

   traceroute 8.8.8.8

5. Scanning Network Ports with Nmap:

   The nmap command is a powerful network scanning tool. To scan open ports on a specific host, you can use:

   nmap 192.168.1.1

   This will display a list of open ports and the services running on them.