Bug 64

Summary: Traceroute will not operate through passt/pasta
Product: passt Reporter: David Gibson <dgibson>
Component: UDPAssignee: nobody
Status: CONFIRMED ---    
Severity: enhancement    
Priority: Low    
Version: unspecified   
Hardware: All   
OS: Linux   

Description David Gibson 2023-07-04 03:27:01 UTC 
Traceroute or similar tools (mtr, tracepath) can't be used through passt, because we don't propagate IP level TTL values to our outgoing sockets.

I believe it would be possible to do this by:
  * Using the IP_TTL socket option to propagate the TTL from UDP packets received on the tap interface to the outgoing UDP sockets
  * Using IP_RECVERR on outward facing UDP sockets to detect time exceeded erorrs and propagate them to the guest with synthesized ICMP packets.