Hi,

This is the issue:

First the setup
-----

System A - WIN XP
System B - Fedora 9

A and B is connected via a wireless DSL router.

ipconfig on A shows the following:
IP Address - 192.168.1.5
Subnet Mask - 255.255.255.0
Default Gateway - 192.168.1.1

ifconfig on B shows the following:

eth0 Link encap:Ethernet HWaddr 00:1D:72:FC:64:78
inet addr:192.168.1.2 Bcast:192.168.1.255 Mask:255.255.255.0
inet6 addr: fe80::21d:72ff:fefc:6478/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:2702 errors:0 dropped:0 overruns:0 frame:0
TX packets:2985 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:1864292 (1.7 MiB) TX bytes:658219 (642.7 KiB)
Interrupt:16

lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:16436 Metric:1
RX packets:4784 errors:0 dropped:0 overruns:0 frame:0
TX packets:4784 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:245304 (239.5 KiB) TX bytes:245304 (239.5 KiB)

A UDP application trying to send test data from A to B (port 5060). The receiver at B is not getting the data.

I used analyser at B (wireshark)..which shows data is coming to B (192.168.1.2) but strangely the UDP application is not receiving the same.

Am I missing something important here?

Please help me pointing it out...

~Thanx
Abhijit

Two possibilities come to mind:

1. You're filtering udp traffic on that port with iptables. (Wireshark still sniffs and reports on data that gets filtered at the host level.)
2. Your application is borked.

Hi Anomie,

Thanks for the comments. But the app is not *borked*. I ran a simple test -

Instead of A sending UDP data to B, I ran the sender application in B itself - this time the receiver app in B got the data.

The data is going through localloop instead of routing it via 192.168.1.2, though the applicatios are binded to IP:192.168.1.2

If I disable the lo - then the receiver does not get any data.

I am perplexed - any hints. It seems there is something wrong in the network configuration perhaps.

Any help much appriciated.

~Thanx
Abhijit

Well, let's start confirming (or not) some things.

On the host that you're trying to push udp packets to, let's see the output of:

• # netstat -lun
• # iptables -nvL

Please put the output in code tags so that we can read it.

Just figured it out yesterday night - iptable was blocking the UDP packets. I added a line to allow it. Now its all fine. Thanks for the hints.

~Abhijit