Luis, I have seen similar problems when iptables has not been compiled and installed correctly (The INSTALL files needs to be read carefully). If your syntax is correct are you are running 1.2.7a on a linux system, are you booting the right kernel that you used to build iptables? Some times this problem also happends because the target module has not been loaded from the library or the kernel. Good luck, Jose. ----- Original Message ----- From: "Luis Miguel Cruz Miranda" <luismi@b2bi.es> To: <netfilter@lists.netfilter.org> Sent: Friday, February 21, 2003 12:41 AM Subject: snat Invalid argument??? (urgent) I execute this line: # iptables -t nat -A POSTROUTING -s 10.1.0.253 -o eth0 -j SNAT --to-source 194.149.216.62 iptables: Invalid argument but it returns Invalid argument???? What is wrong here? Luis Miguel Cruz Miranda. | B2B INTEGRAL, S.A. CCNA - Systems Administrator | Pol. Ind. de Asipo | C/A - Parcela 86-C Tel: +34 902 506 605 | 33.428 - CAYES - LLANERA Fax:+34 985 980 794 | ASTURIAS (ESPAŅA/SPAIN)