How to Troubleshoot Networks in Unix

Troubleshooting a network can be a difficult task. Typically, only one thing is wrong with the network configuration; however, finding that one thing might take a lot of time and effort. The problem could be hardware related or software related or both.

Instructions

1. Investigate all hardware connections. Make sure all network cables are plugged in.

2. Make sure all network cables are plugged into a router and the router is turned on if you're connecting to a router.

3. Open a command window on your Unix system. Look under the Utilities menu on your Unix operating system.

4. Execute the "ping" command once the command window is open. Ping the host name of the machine that your network is having trouble reaching. A successful ping will come back with a "100% packet return." Some Unix systems will display "Host name is alive." Either result is good.

5. Investigate the routing table on the Unix system if the ping command comes back with "0% packet" or "the machine is not responding."

6. Execute the netstat -rn command to look at the routing table. The routing table will show you how the network traffic is resolved. Each line from the netstat command will show you one route defined on your network. The network problem might be that a route got dropped from the routing table.

7. Look for another common network problem if the above suggestions don't work. An interface might have been dropped. Invoke the ifconfig -a command. Look for interfaces that are up.

8. Run ifconfig up command for any interface that is down. This will enable that interface.

Tips & Warnings

• A network cable might be bad. Replace a bad network cable with a spare. Sometimes you might not know a network cable is bad until you replace it.

• The network problem might exist in your commercial router. If that is the case, consider contacting the router company for additional support.