0

I am running into a roadblock that I thought I could troubleshoot but have not been able to.

I am running a Asus RT-AC86U router (192.168.120.1) with Merlin and am trying to set up a site to site VPN config. I am using a dedicated openVPN machine (192.168.120.55) behind the router and not the router itself since the transfer rates on the router are too slow.

SO, I am trying to forward all requests for the remote subnet (192.168.110.1) to the openvpn machine gateway (192.168.120.55) using Asus' static route list.
LAN - static route list:
LAN - static route list

BUT, after applying the static route, then having the site-to-site VPN connected and trying to ping and tracert towards the 192.168.110.1 subnet, none of the requests are even sent to the VPN gateway. And checking the router's routing table, the 192.168.110.1 destination is nowhere in that table.

What am I missing? Any pointers would be greatly appreciated.

Improve this question
2
  • Check with Wireshark what’s happening. Your router might be sending ICMP redirects, because the gateway is on the local network. Some hosts do not accept these. // How are you check the router’s current routing table?
    – Daniel B
    Commented Mar 22, 2023 at 8:16
  • thanks for commenting but it is solved below. to answer your question, the router has a page that displays the current routing table.
    – anothernguyen
    Commented Mar 24, 2023 at 20:45

1 Answer 1

Reset to default
0

The only unusual thing in your screenshot (possible firmware bugs aside) is that the destination has non-zero 'host' bits. For a /24 prefix (with 255.255.255.0 as the mask), you should have 192.168.110.0 as the destination. While some systems just ignore the host bits in such situations, other systems are stricter and explicitly refuse such prefixes (as it makes no sense having them set).

Even though it is common to ignore .0 and .255 addresses, do not overdo it – they merely have a special purpose within the /24 address range but they're still very much part of the range.

(And only the final gateway that controls the /24 gets to decide whether they're in fact special or not; as far as your RT-AC86U is concerned, they're just as usable as any other address.)

Improve this answer
1
  • Wow. that was exactly it! I thought it would ignore the host bit and it seemed like a minor point, but duly noted your explanation! Thank you so much, more hours of headaches!
    – anothernguyen
    Commented Mar 24, 2023 at 20:42

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .