Joerg Pommnitz wrote: [snip] >tcpdump: listening on ppp1 >15:29:46.120000 193.254.167.86.1029 > 193.254.165.18.12345: udp 8 (DF) >15:29:47.120000 193.254.167.86.1029 > 193.254.165.18.12345: udp 8 (DF) >15:29:48.120000 193.254.167.86.1029 > 193.254.165.18.12345: udp 8 (DF) >15:29:49.120000 193.254.167.86.1029 > 193.254.165.18.12345: udp 8 (DF) >15:29:50.120000 193.254.167.86.1029 > 193.254.165.18.12345: udp 8 (DF) >15:29:51.120000 193.254.167.86.1029 > 193.254.165.18.12345: udp 8 (DF) >15:29:52.120000 193.254.167.86.1029 > 193.254.165.18.12345: udp 8 (DF) >jpo>./tcpdump -i ppp0 udp >tcpdump: listening on ppp0 >15:29:46.100000 193.254.167.86.1029 > 193.254.165.18.12345: udp 8 (DF) >15:29:47.600000 193.254.167.86.1029 > 193.254.165.18.12345: udp 8 (DF) >15:29:48.080000 193.254.167.86.1029 > 193.254.165.18.12345: udp 8 (DF) >15:29:49.560000 193.254.167.86.1029 > 193.254.165.18.12345: udp 8 (DF) >15:29:50.100000 193.254.167.86.1029 > 193.254.165.18.12345: udp 8 (DF) >15:29:51.600000 193.254.167.86.1029 > 193.254.165.18.12345: udp 8 (DF) >15:29:52.090000 193.254.167.86.1029 > 193.254.165.18.12345: udp 8 (DF) >15:29:53.560000 193.254.167.86.1029 > 193.254.165.18.12345: udp 8 (DF) > >So I see the packets going leaving from ppp1 and arriving on ppp0, but >I do NOT see them in my little program. > >Does anybody know where and why they get lost? > I'm guessing that your kernel is performing reverse path filtering -- i.e., it "knows" that packets from that source address should be coming over the loopback interface, and not ppp0. I suggest that you "echo 0 > /proc/sys/net/ipv4/conf/ppp0/rp_filter" to disable reverse path, and "echo 1 > /proc/sys/net/ipv4/conf/ppp0/log_martians" so you will get log messages for similar stuff. > >Note that this program works fine without binding to a device: > >jpo>./rtt -a 193.254.165.18 >rtt (0:189) >rtt (0:228) >rtt (0:148) >rtt (0:161) > >So I'm a little bit lost. Any ideas? > >Regards > Jörg > >--- Joerg Pommnitz <pommnitz@yahoo.com> wrote: > >>Hi List, >>I want to do something slightly unusual and need a little push in the >>right direction. I have a Linux box (2.4.18) with two GPRS devices >>attached as ppp0 and ppp1. ppp0 has address A, ppp1 has address B. I >>want >>to route traffic to address B (e.g. ppp1) through interface ppp0, e.g >>despite the fact that address B is local I want to sent it through the >>external net. My first naive try was to >>route add -host "address B" ppp0 >> >>This does not do what I want. Traceroute still shows that address B is >>just a single hop and 1 ms away. >> >>How can I get Linux to do what I want (e.g. not to optimize the >>routing). >> >>Regards >> Jörg >> >>P.S.: Just in case you are wondering: This is to make some round trip >>measurements. >> > > >===== > -- Casey Carter Casey@Carter.net ccarter@uiuc.edu AIM: cartec69 - : send the line "unsubscribe linux-net" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
