Help needed with routing problems

[Javier Castillo Alcibar <Castillo@xxxxxxxxxx>]

        Hi there,

        I have a very, very strange problem. My english is very poor, so I am going to be very short:

1) I insert a new route:
linux-rt:/proc/net# route add -host 194.69.249.21 gw 195.53.58.97

2) I ping the new host:
linux-rt:/proc/net# ping 194.69.249.21 &
[1] 8904
PING 194.69.249.21 (194.69.249.21): 56 data bytes

3) And I want to what happens:
linux-rt:/proc/net# tcpdump -v -n -i eth5 src or dst 194.69.249.21
tcpdump: listening on eth5
10:58:28.348284 195.53.58.98 > 194.69.249.21: icmp: echo request (ttl 64, id 43415)
10:58:28.349563 195.53.58.98 > 194.69.249.21: icmp: echo request (ttl 63, id 43415)  ????
10:58:29.348275 195.53.58.98 > 194.69.249.21: icmp: echo request (ttl 64, id 43419)
10:58:29.349578 195.53.58.98 > 194.69.249.21: icmp: echo request (ttl 63, id 43419) ?????
10:58:30.348258 195.53.58.98 > 194.69.249.21: icmp: echo request (ttl 64, id 43421)
10:58:30.349546 195.53.58.98 > 194.69.249.21: icmp: echo request (ttl 63, id 43421) ?????

        It seems that the packets are duplicated, but with a lower ttl ¿?¿?

Ok, the ping (icmp) is crazy, let's try with tracepath tool (udp):

4) Thx Kuznet for your tool:
linux-rt:/proc/net# tracepath 194.69.249.21 &
[1] 9177
 1?: [LOCALHOST]      pmtu 1500

5) Let's see:

linux-rt:/proc/net# tcpdump -v -n -i eth5 src or dst 194.69.249.21 1:  no reply

tcpdump: listening on eth5
11:06:16.188295 195.53.58.98.1475 > 194.69.249.21.44448: udp 1472 (DF) (ttl 2, id 44275)
11:06:17.188281 195.53.58.98.1475 > 194.69.249.21.44449: udp 1472 (DF) (ttl 2, id 44278)
 2:  no reply
11:06:18.188368 195.53.58.98.1475 > 194.69.249.21.44450: udp 1472 (DF) (ttl 3, id 44280)
11:06:19.188284 195.53.58.98.1475 > 194.69.249.21.44451: udp 1472 (DF) (ttl 3, id 44282)
11:06:20.188279 195.53.58.98.1475 > 194.69.249.21.44452: udp 1472 (DF) (ttl 3, id 44284)
 3:  no reply
11:06:21.188352 195.53.58.98.1475 > 194.69.249.21.44453: udp 1472 (DF) (ttl 4, id 44286)
11:06:22.188280 195.53.58.98.1475 > 194.69.249.21.44454: udp 1472 (DF) (ttl 4, id 44288)
11:06:23.188280 195.53.58.98.1475 > 194.69.249.21.44455: udp 1472 (DF) (ttl 4, id 44292)
 4:  no reply
11:06:24.188340 195.53.58.98.1475 > 194.69.249.21.44456: udp 1472 (DF) (ttl 5, id 44294)
11:06:25.188279 195.53.58.98.1475 > 194.69.249.21.44457: udp 1472 (DF) (ttl 5, id 44300)

        This time, the packets are not duplicated.............¿?¿?¿?

        I have a kernel 2.2.16

        Thx all.

Javier Castillo Alcíbar - castillo@xxxxxxxxxx
Alhambra Systems, S.A. - www.alhsys.com
c/Albasanz 14, 28037 Madrid
Tel.:  +34 91 787 23 00
Fax.: +34 91 787 23 01