FreeBSD 6.3 gre and traceroute
sclark46 at earthlink.net
Wed Nov 12 12:57:46 PST 2008
Julian Elischer wrote:
> Stephen Clark wrote:
>> When I run traceroute thru a gre it doesn't seem to decrement the
>> ttl, so I get * * * for that hop. Can this be fixed?
> you will need to define the setup and question better.
> TTL is controlled by the IP stack which is unaware of which interface
> it came in on and doesn't care which interface it goes out on. That
> includes GRE interfaces.. Is it freebsd at both ends?
> BTW * * * would come from an EXTRA decrement
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FreeBSD workstation 10.0.129.1<-->10.0.128.1 Freebsd FW "A" with gre over ipsec
tunnel<---->FreeBSD FW "B" with gre over ipsec tunnel 192.168.3.1<--->
192.168.3.86 linux workstation
$ sudo traceroute 192.168.3.86
traceroute to 192.168.3.86 (192.168.3.86), 64 hops max, 40 byte packets
1 HQFirewallRS.com (10.0.128.1) 0.575 ms 0.423 ms 0.173 ms
2 * * *
3 192.168.3.86 (192.168.3.86) 47.972 ms 45.174 ms 49.968 ms
No response from the FreeBSD "B" box.
When I do a tcpdump on "B" of the gre interface I see UDP packets
with a TTL of 1 but no ICMP repsonse packets being sent back.
If I do the traceroute from the linux workstation 192.168.3.86 I get
similar results - I don't see a response from the FreeBSD "A" box.
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