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Old 12-21-2009, 12:53 PM   #1
vragukumar
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Registered: Dec 2009
Posts: 6

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Intercept UDP packet in transparent bridge mode


Hello All,

I have setup two servers as shown below

---------
|Internet |
---------
|
|
---------
|DSL Modem|
---------
|
| eth0
---------
|Server 1 |
---------
| eth1(Server1)
|
| eth0(Server2)
---------
|Server 2 |
---------

Server1 : Has eth0 and eth1 bridged, bridge has a Public IP.Runs Kamailio and rtpproxy
Server2 : Configured with a Public IP.Runs Asterisk
-------------------------------------------------------------------------
The bridge between eth0 and eth1 of Server1 has been setup using the shell script:
brctl addbr br0
brctl stp br0 on
brctl addif br0 eth0
brctl addif br0 eth1
ifdown eth0 1>/dev/null 2>&1
ifdown eth1 1>/dev/null 2>&1
ifconfig eth0 0.0.0.0 up
ifconfig eth1 0.0.0.0 up
ifconfig br0 64.221.148.221 netmask 255.255.255.224 up
route add default gw 64.221.148.220
for file in br0 eth0 eth1
do
echo "1" > /proc/sys/net/ipv4/conf/${file}/proxy_arp
echo "1" > /proc/sys/net/ipv4/conf/${file}/forwarding
done;
echo "1" > /proc/sys/net/ipv4/ip_forward
-------------------------------------------------------------------------
Is it possible to intercept packets on UDP port(port_number) at Server1 destined to Server2 before they arrive at Server2 ? If so, how can this be done ?

Thanks in advance for your help.

Regards,
Vikram.

Last edited by vragukumar; 12-21-2009 at 12:54 PM.
 
Old 12-21-2009, 01:33 PM   #2
David1357
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Registered: Aug 2007
Location: South Carolina, U.S.A.
Distribution: Ubuntu, Fedora Core, Red Hat, SUSE, Gentoo, DSL, coLinux, uClinux
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Quote:
Originally Posted by vragukumar View Post
Is it possible to intercept packets on UDP port(port_number) at Server1 destined to Server2 before they arrive at Server2 ? If so, how can this be done ?
Try using the libnetfilter_queue library.
 
Old 12-22-2009, 08:36 AM   #3
kirukan
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Registered: Jun 2008
Location: Eelam
Distribution: Redhat, Solaris, Suse
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Bridge working in layer 2 level, so did you check about ebtables?
 
  


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