Cristian Grigoriu wrote:
>KobrAs wrote:
>
>
>
>>mtr merge default pe icmp si traceroute merge default pe udp
>>incearca traceroute -I 172.16.72.100
>>
>>
>
>Bun, dar asta tot nu ma lamureste. Masina 72.100 primeste un pachet UDP
>sau ICMP, nu conteaza, cu TTL 1 de la 1.30, genereaza ICMP Time Expired
>in Transit pe care trebuie sa-l trmita inapoi la 1.30. Dupa cum am mai
>spus, 72.100 NU are ruta nici spre host 1.30 si nici spre net 1.0.
>
un tcpdump pe masina 72.100 ce zice ?
in special pachetele generate ar fi interesante.
>Si de ce apare 72.100 de la hopul 6 la 12?
>
># traceroute -I 172.16.72.100
>traceroute to 172.16.72.100 (172.16.72.100), 30 hops max, 38 byte packets
> 1 192.168.1.1 (192.168.1.1) 0.688 ms 0.639 ms 0.623 ms
> 2 172.24.79.57 (172.24.79.57) 21.112 ms 21.030 ms 20.935 ms
> 3 192.168.39.1 (192.168.39.1) 105.048 ms 114.248 ms 106.910 ms
> 4 172.24.78.33 (172.24.78.33) 50.553 ms 45.481 ms 49.768 ms
> 5 172.24.78.34 (172.24.78.34) 48.638 ms 52.111 ms 50.282 ms
> 6 172.16.72.100 (172.16.72.100) 48.581 ms 51.633 ms 74.483 ms
> 7 172.16.72.100 (172.16.72.100) 89.177 ms 69.389 ms 60.785 ms
> 8 172.16.72.100 (172.16.72.100) 137.864 ms 138.678 ms 162.063 ms
> 9 172.16.72.100 (172.16.72.100) 224.838 ms 142.385 ms 142.588 ms
>10 172.16.72.100 (172.16.72.100) 137.857 ms 237.620 ms 148.320 ms
>11 172.16.72.100 (172.16.72.100) 99.542 ms 89.013 ms 88.477 ms
>12 172.16.72.100 (172.16.72.100) 111.632 ms 83.758 ms 74.023 ms
>13 * * *
>14 * * *
>
aici e usor neclar si pt mine. de amorul artei se poate simula
comportamentul de mai sus punind pe routerele de pe parcurs ceva de genul
iptables -A POSTROUTING -t nat -p imcp --icmp-type echo-reply -j
SNAT --to 172.16.72.100
dar ma indoiesc ca e situatia ta. de altfel cred ca desi apare de 6 ori,
de fapt e un singur router care se screme si nu stie cum sa te faca sa
ii intelegi dilemele existentiale prin care trece.
>
># ping 172.16.72.100
>PING 172.16.72.100 (172.16.72.100) from 192.168.1.30 : 56(84) bytes of data.
>
>--- 172.16.72.100 ping statistics ---
>7 packets transmitted, 0 received, 100% loss, time 6015ms
>
>
$IPT -A INPUT -p icmp --icmp-type echo-reply -i $EXTERNAL_INTERFACE1 -j DROP
$IPT -A INPUT -p icmp --icmp-type time-exceeded -i $EXTERNAL_INTERFACE1
-j ACCEPT
si o sa ai traceroute fara a avea ping reply.
--
My mechanic told me, "I couldn't repair your brakes, so I made your horn louder."
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