Is traceroute supposed to work in user mode networking (slirp) ?

[Ottavio Caruso]

[Originally asked on qemu-discuss but I didn't get any feedback.
Thanks for your patience.

Hi,

I have enabled pinging from the guest changing the
"net.ipv4.ping_group_range" on my Linux host. I can now ping any host
using icmp. But I cannot get  traceroute to work with standard udp
from any of my guests.

$ traceroute 8.8.8.8
traceroute to 8.8.8.8 (8.8.8.8), 64 hops max, 40 byte packets
 1  * * *
 2  * * *
 3  * * *
 4  * * *
[and so on]

And if I use traceroute over icmp, I only get one hop shown:

$ traceroute -I 8.8.8.8
traceroute to 8.8.8.8 (8.8.8.8), 64 hops max, 60 byte packets
 1  dns.google (8.8.8.8)  26.147 ms  27.88 ms  20.048 ms

I have tested this with various guest OSes (OpenBSD, FreeBSD, NetBSD,
Small Damn Linux).

I've played around with various virtual interfaces but I have the same result.

Any clues? Is this intended behaviour? Any workarounds that don't
involve tap/tun/bridges?

--
Ottavio Caruso