Hi, Am using OpenBSD as for routers and am getting quite a few traceroutes which have traversed them and show the wrong IP/rDNS.
It seems that OpenBSD sends the reply from the best route, rather than the interface that the traffic came in on - like a real router would do. This manifests in some odd traceroutes, because external hops are over one transit provider, but then the IP/rDNS of the router is that of a completely different transit interface. This is most confusing if you are not aware / used to it. This is a problem in Linux too, but it has a sysctl toggle to resolve it: net.ipv4.icmp_errors_use_inbound_ifaddr: https://sysctl-explorer.net/net/ipv4/icmp_errors_use_inbound_ifaddr/ "If non-zero, the message will be sent with the primary address of the interface that received the packet that caused the icmp error. This is the behaviour network many administrators will expect from a router. And it can make debugging complicated network layouts much easier." Please could something similar be implemented in OpenBSD? I'm told that NetBSD has this, but it's not easily portable: https://github.com/NetBSD/src/blob/trunk/sys/netinet/ip_icmp.c#L768= Thanks, Ian
