Hai, when will the netfilter conntrack helper funtion will be called for a router? It will be in input chain, forward chain or output chain for the first packet detected matching the helper registration parameters. i printed skbuff contents for TFTP which i found after SNAT done .will it not be before doing NAT?..can any one guide me if i am wrong My setup is client router server 192.168.0.1 10.145.2.23(wan) 10.145.6.78 c2b682a4: 17 192.168.0.1:32770 -> 10.145.6.78:69 rep tuple c2b682bc: 17 10.145.6.78:69 -> 10.145.2.23:32770 and skbuff contents as 10.145.2.23:32770 -> 10.145.6.78:69 can i directly change tupule contents to redirect the packet to any ipaddress or port? regards, murugan The information contained in this electronic message and any attachments to this message are intended for the exclusive use of the addressee(s) and may contain proprietary, confidential or privileged information. If you are not the intended recipient, you should not disseminate, distribute or copy this e-mail. Please notify the sender immediately and destroy all copies of this message and any attachments. WARNING: Computer viruses can be transmitted via email. The recipient should check this email and any attachments for the presence of viruses. The company accepts no liability for any damage caused by any virus transmitted by this email. www.wipro.com