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23.7 Legacy Series / Re: [Tutorial/Call for Testing] Enabling Receive Side Scaling on OPNsense
« on: January 08, 2024, 01:18:25 pm »
We tested RSS on a slow PC Engines APU2 device in combination with an IPsec Site to Site VPN.
With enabled RSS, there are some issues with unbound receiving DNS packets through the VPN tunnel:
- unbound has a DNS override for a specific domain, the IP of the authorative server for that override is set to an IP inside the IPsec P2 remote network.
- The outgoing network interface in unbound is set to the interface, the IPsec P2 local network resides in.
With a packet capture we can see the DNS answer packets arriving at the IPsec P2 local network, but unbound does not see them.
With disabled RSS this setup is working without any issues.
With enabled RSS, there are some issues with unbound receiving DNS packets through the VPN tunnel:
- unbound has a DNS override for a specific domain, the IP of the authorative server for that override is set to an IP inside the IPsec P2 remote network.
- The outgoing network interface in unbound is set to the interface, the IPsec P2 local network resides in.
With a packet capture we can see the DNS answer packets arriving at the IPsec P2 local network, but unbound does not see them.
With disabled RSS this setup is working without any issues.