Hi Konstantin, Thanks for your kind reply. You can check the iptables output at : http://pastebin.com/i3zUfVeb. I hope that this will give you enough clue in right direction. With Regards, Vijay Thakur ====================================================================================================================== Message: 3 Date: Fri, 3 Aug 2012 17:38:23 +0300 From: "Konstantin M."<evilzluk(a)gmail.com> Subject: Re: [SR-Users] kernel: nf_ct_sip: dropping packetIN= OUT=eth0 Error To: "SIP Router - Kamailio (OpenSER) and SIP Express Router (SER) - Users Mailing List"<sr-users(a)lists.sip-router.org> Message-ID: <CAEYtTzdeY88X-GC+wDwLou+smsB60h+M36h7xwCu448V0YtD2g(a)mail.gmail.com> Content-Type: text/plain; charset="iso-8859-1" Looks like your firewall is passing a state RELATED,ESTABLISHED and don't have a permit rule for a state NEW. Check your iptables or simply do a command: iptables-save > /tmp/iptables.txt and paste this file (/tmp/iptables.txt) to pastebin 2012/8/3 Vijay Thakur<vijay.thakur(a)loopmethods.com>