I have no idea why this VPN is blocking only SOME traffic on a specific port

GregB Posts: 1


I've got a VPN300. I have no idea how old it is, it's an inherited hardware with my role.

That said, I can see packets coming into the public side with the UI packet sniffer, but no corresponding packet leaving to the right destination.

I'm sorry if I'm a bit unclear. I've been fighting with this for the last 9 hours straight.

So basically, we have a public IP, which is handling our IPSEC tunnel traffic over 4500 and 500 bypassing zyxel and tying into one of our VM's we have behind Zyxel. We've setup the Nat, we even have an identical IPsec server running. This setup even worked til 9 hours and 20 minutes ago.

I'm no zyxel expert, but I'm fairly solid working my around a network and getting something to work, but this setup is leaving me hard pressed. I see nothing in the logs except some ARP about a different server that's also running IPSEC, which made me wonder if there was some sort of ARP cache corruption or something of that nature.

But after digging into the docs and accessing the device over SSH… I have found 2 commands that work. ping and show interface Wan2 proxy-arp status

Every other command gives me a subshell. Would love a regular old terminal, like bash or something. But in the meantime, I could definitely use your guys help figure this out. Any advice?

All Replies

  • Cyrill_U
    Cyrill_U Posts: 3
    First Comment

    Could you probably clarify a little bit, please?
    IPSec means Network x Network communication. What kind of traffic (protocol, type) is blocked - and in what destination?

    I mean, if you have IPSec and no security policy (firewall) rules defined (remember, there are 2 IPSec endpoints, check both), you should have normal traffic flowing back and forth. Probably, the device you're trying to reach from another network has different gateway and/or route?

    Anyway, good luck in your investigations)

  • Zyxel_Stanley
    Zyxel_Stanley Posts: 1,366  Zyxel Employee
    First Anniversary 10 Comments Friend Collector First Answer

    The issue has fixed by firmware. You can download firmware by this thread.

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