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TCP tracerouting with a Technicolor 582n

Community Veteran
Posts: 5,187
Thanks: 486
Fixes: 21
Registered: ‎10-06-2010

TCP tracerouting with a Technicolor 582n

I've just noticed that attempting to do a traceroute by sending TCP packets seems to be totally broken with a Technicolor 582n router.

# traceroute -q 1 -N 1 -T -p 80 community.plus.net
traceroute to community.plus.net (212.159.9.110), 30 hops max, 52 byte packets
1  192.168.1.254 (192.168.1.254)  3.967 ms
2  *
3  link-a-central10.pcl-gw01.plus.net (212.159.2.176)  24.443 ms
4  *
5  *
6  *
7  *
8  *
9  community.plus.net (212.159.9.110)  32.202 ms

The first missing reply is in the firewall log, no sign of the rest:
{admin}=>:syslog msgbuf show
...
<81> Feb 19 21:12:32 FIREWALL icmp check (1 of 6): Protocol: ICMP  Src ip: 195.166.128.186 Dst ip: 87.112.my.ip Type: Time Exceeded Code: Time to Live exceeded in Transit

A traceroute using ICMP (which is what Windows tracert.exe uses) works as expected, but I thought TCP traceroutes can be more useful in certain cases. 10.2.5.2 FO firmware being used on ADSL, and it doesn't seem to make any difference changing from firewall config tcpchecks=exact to tcpchecks=none.