We have a Zywall USG 300 which dials ipsec to a Server 2008 R2 server.
This was working until recently when any attempt to communicate with the server sees the following in the logs.
error IPSec SPI:0x0 SEQ:0x0 No rule found, Dropping packet [count=2] internal-ip external-ip ipsec
There hasn't been a change on the network... (at least that we're aware of) to explain it stopping working
We have Zywal routes set up
- Anything incoming on the VPN routes to our LAN
- Anything from our LAN destined for the external network routes through the VPN
We have firewall rules set
- from the external network to the public IP endpoint => allow
- from the external network to the public ip endpoint => allow
- from the LAN to the external network => allow
- from the external network to the LAN => allow
Networking isn't my strong-point(!!) and I'm not sure where to begin troubleshooting this...
Any advice appreciated...