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Troubleshooting Internet Connectivity

This is a guide intended to show some useful steps for troubleshooting Internet connectivity. Although not specific to ClearOS only, it can be useful if you cannot get out to the Internet.

Another guide exists for even greater detail that can be used generally for ALL types of network connections. If this does not help you with your issue, refer to that guide here.


You can work either forwards or backwards in this guide. I present them working your way backward since the conclusions seem to work better when presented this way. From the workstation which cannot get to the internet perform the following:

    • If you can ping this but you can't surf this then the problem usually lies with your web browser or a proxy server if you are using one.
  • Ping (google's name server and easy to remember).
    • If you can ping this address, then your problem is DNS resolution.
  • Ping the IP address of the default gateway of your firewall.
    • By successfully pinging the address you confirm that the settings on your firewall permit access and that NAT is working but because you cannot get further, this means that your failure is with your firewall blocking policy or your ISP or further down the road. I usually follow up by running a traceroute to and performing the same tests from the firewall itself. If it fails from the firewall itself then the problem lies with the ISP. If the firewall works fine, check the firewall rules.
  • Ping the IP address of your gateway's external network card.
    • A successful ping to this address means that your gateway is set correctly on your workstation. Failure usually means that your gateway is not configured correctly on your workstation.
  • Ping the IP address of your gateway's internal network card.
    • A success here means that your network can talk ok. A failure here means that your network is NOT on the same subnet as your gateway or that there is a hardware connectivity problem on your network.


content/en_us/kb_troubleshooting_internet_connectivity.txt · Last modified: 2014/12/18 17:04 (external edit)