Mailing List Archive: Wrong source IP address!

Hi,

VNPC works on my PC. However, on an ARM device i am having problems
using this pre-compiled version:
http://www.gfd-dennou.org/library/Linux/debian/pool/main/v/vpnc/

Tcpdump shows the packets going out of eth0 with the source IP address
set as the internal tunnel end IP address (129.150.146.51) and not the
IP of the eth0 interface. Of course the path from eth0 to the VPN
gateway does *not* work!

Can anyone give me some pointers as to why the wrong source address is
set?
Is the config below correct?
ie. "inet addr:129.150.146.51 P-t-P:129.150.146.51" for the tun0 device

Thanxs und vielen Dank!
Andy

Here is the TCP trace and config

Ping to the VPN Gateway at 192.18.17.12 works

~ # ping 192.18.17.52
PING 192.18.17.52 (192.18.17.52): 56 data bytes
04:13:34.831473 192.168.123.50 > 192.18.17.52: icmp: echo request (DF)
04:13:34.943031 192.18.17.52 > 192.168.123.50: icmp: echo reply (DF)
64 bytes from 192.18.17.52: icmp_seq=0 ttl=119 time=113.4 ms

04:13:35.827872 192.168.123.50 > 192.18.17.52: icmp: echo request (DF)
04:13:35.842733 192.18.17.52 > 192.168.123.50: icmp: echo reply (DF)
64 bytes from 192.18.17.52: icmp_seq=1 ttl=119 time=16.7 ms

--- 192.18.17.52 ping statistics ---
2 packets transmitted, 2 packets received, 0% packet loss
round-trip min/avg/max = 16.7/65.0/113.4 ms

Ping to an internal IP address behind the VPN gateway fails
tcpdump shows the wrong source IP (.51) and of course nothing coming
back! This does work on a PC with the exact same configuration as on
the ARM device.

~ # ping 129.158.138.16
PING 129.158.138.16 (129.158.138.16): 56 data bytes
13:37.082242 129.150.146.51 > 192.18.17.52:ESP(spi=0x2be40bc5,seq=0x5de)
13:38.082014 129.150.146.51 > 192.18.17.52:ESP(spi=0x2be40bc5,seq=0x5df)
13:39.081801 129.150.146.51 > 192.18.17.52:ESP(spi=0x2be40bc5,seq=0x5e0)
--- 129.158.138.16 ping statistics ---
3 packets transmitted, 0 packets received, 100% packet loss

Here is the routing table etc.

~ # route -ne
Kernel IP routing table
Destination Gateway Genmask FlagsMSS Window irtt
Iface
192.18.17.52 192.168.123.1 255.255.255.255 UGH 1500 0 0 eth0
192.168.123.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0
0.0.0.0 129.150.146.51 0.0.0.0 UG 0 0 0 tun0

~ # ifconfig tun0
tun0 Link encap:Point-Point Protocol
inet addr:129.150.146.51 P-t-P:129.150.146.51 Mask:255.255.255.255
UP POINTOPOINT RUNNING NOARP MULTICAST MTU:1412 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:1516 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:10
RX bytes:0 (0.0 B) TX bytes:125555 (122.6 KiB)

# uname -r
2.4.19-rmk6-pxa1-hh36

hi,

> Tcpdump shows the packets going out of eth0 with the source IP address
> set as the internal tunnel end IP address (129.150.146.51) and not the
> IP of the eth0 interface. Of course the path from eth0 to the VPN
> gateway does *not* work!

> Can anyone give me some pointers as to why the wrong source address is
> set?

hmm.. could you search the syslog for "local address for ..."?

> Is the config below correct?
> ie. "inet addr:129.150.146.51 P-t-P:129.150.146.51" for the tun0 device

the remote end of this tunnel does not have a designated IP at all,
so I had to "invent" one...

> ~ # route -ne
> Kernel IP routing table
> Destination Gateway Genmask FlagsMSS Window irtt
> Iface
> 192.18.17.52 192.168.123.1 255.255.255.255 UGH 1500 0 0 eth0
> 192.168.123.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0
> 0.0.0.0 129.150.146.51 0.0.0.0 UG 0 0 0 tun0

this route should be without gateway ...
"route add default dev tun0"

cu
maurice