SOLVED Can't ping gateway

[jboyce]

I have a Silver Support contract, but since it is after 6pm on Friday, I am not going to get any assistance with it until at least Monday morning. In the mean time I thought I would post my issue here in hopes that someone else might have some suggestions on what else I should look at to diagnose and resolve this issue. Below is the brief synopsis. I can certainly provide more details if needed.

I was installing a new network gateway that included setting up OpenVPN. In doing this I was changing our network addressing from 192.168.112.0/24 to 192.168.120.0/24. The TrueNAS box had been running on the network to rsync files from the server it was replacing. I installed the new gateway box, then changed the network settings on the TrueNAS box. When testing the VPN connection we realized that we could not access the TrueNAS box behind the gateway (router) / VPN. Troubleshooting lead us to realize that the gateway / router box at 192.168.120.2 could not ping the TrueNAS box at 192.168.120.10. Likewise the TrueNAS box could not ping the gateway box. The laptop connected to the common switch at 192.168.120.100 could ping both the gateway and the TrueNAS box and was being used to configure everything.

I suspect I messed up some networking configuration when changing the TrueNAS box, but I can't seem to see where it might be. The steps I took to change the network settings on the TrueNAS box was at the serial console, select configure network interface, change the interface setting to DHCP (I don't think I chose delete interface first). After seeing the new address displayed (I think it was 192.168.120.106), then logged into the GUI using that address from the laptop and changed the network interface back to static, giving it the 192.168.120.10 address. The GUI currently shows the interface address of 192.168.120.10 with a default route of 192.168.120.2 (the gateway/router box), and name server of 192.168.120.2, all of which appears correct.

Thanks,
Jeff

 

[Samuel Tai]

Try clearing the ARP cache on your router. It's stuck with the 192.168.120.106 ARP.

 

[jboyce]

I think I may have solved it. Initial tests are positive, but want to do further diagnostics to be sure. Wanted to post what I found now so I don't forget.

I compared the ARP cache tables between the gateway and the TrueNAS box. Both tables showed the correct respective IP addresses for everything. However, in the gateway ARP table the MAC address for the TrueNAS box was incorrect (the IP address was correct). As soon as I deleted the listing in the gateway for the TrueNAS box that had the incorrect MAC address, I was able to ping both directions between the gateway and the TrueNAS box.

Thanks for your guidance. I figured it had to be something like this, it was just unfamiliar territory for me.

Jeff