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-   -   tracert/traceroute (http://www.linuxquestions.org/questions/linux-networking-3/tracert-traceroute-507912/)

dav_y2k 12-06-2006 11:54 AM

tracert/traceroute
 
Hi all,
I have a small lab at home where I have a linux box (Fedora core 5) running iptables everything works accordingly but I noticed the following:

when I do a tracert from a windows machine I get
C:\Documents and Settings\Administrator>tracert www.google.com

Tracing route to www.l.google.com [66.102.7.99]
over a maximum of 30 hops:

1 <1 ms <1 ms <1 ms 10.10.1.1
2 * * * Request timed out.
3 * * * Request timed out.
4 14 ms 15 ms 15 ms 221.184.12.65
5 16 ms 16 ms 17 ms 125.206.149.241
6 15 ms 14 ms 14 ms 60.37.11.37
7 17 ms 15 ms 15 ms 210.254.188.197
etc...

but on the linux box I get the following:

[root@ADONAI ~]# traceroute www.google.com
traceroute to www.google.com (66.102.7.147), 30 hops max, 40 byte packets
1 * * *
2 * * *
3 * * *
4 * * *
5 * * *
6 * * *


can anyone explain why??

thanks in advance.

amitsharma_26 12-06-2006 12:25 PM

Because with windows, tracert send icmp echo requests with small ttl values which further goes through your router & get reponse back with icmp type 11 replies But on the other side while you do traceroute from linux, it sends udp packets from source with small ttl values & further the router respond with icmp time exceeded replies (type 11).

So probably your iptables will be blocking udp packets & hence its not working in the latter case.


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