topic Re: Microsoft L2TP connection from behind PIX in Network Security https://community.cisco.com/t5/network-security/microsoft-l2tp-connection-from-behind-pix/m-p/239804#M563241 <HTML><HEAD></HEAD><BODY><P>It's been a while since I screwed around with L2TP but I recall that one of the biggest limitations to L2TP is that the original packets cannot be NAT'ed at all. That is, not PAT'ed nor 1:1 NAT'ed. The packets have to arrive at the termination device unchanged. You may want to check into this and make sure my info is not outdated.</P><P></P><P>Hope this helps.</P><P></P><P>Scott</P></BODY></HTML> Thu, 12 Aug 2004 13:01:36 GMT scoclayton 2004-08-12T13:01:36Z Microsoft L2TP connection from behind PIX https://community.cisco.com/t5/network-security/microsoft-l2tp-connection-from-behind-pix/m-p/239803#M563240 <P>Hi,</P><P></P><P>I'm trying to get a Microsoft native L2TP VPN client to go from behind my PIX to a VPN site on the Internet. It doesn't work. My PIX is running PAT for the outbound connections. My client gets to the "Verifying username and password" stage and hangs.</P><P></P><P>Suggestions?</P> Fri, 21 Feb 2020 07:33:50 GMT https://community.cisco.com/t5/network-security/microsoft-l2tp-connection-from-behind-pix/m-p/239803#M563240 cboykin 2020-02-21T07:33:50Z Re: Microsoft L2TP connection from behind PIX https://community.cisco.com/t5/network-security/microsoft-l2tp-connection-from-behind-pix/m-p/239804#M563241 <HTML><HEAD></HEAD><BODY><P>It's been a while since I screwed around with L2TP but I recall that one of the biggest limitations to L2TP is that the original packets cannot be NAT'ed at all. That is, not PAT'ed nor 1:1 NAT'ed. The packets have to arrive at the termination device unchanged. You may want to check into this and make sure my info is not outdated.</P><P></P><P>Hope this helps.</P><P></P><P>Scott</P></BODY></HTML> Thu, 12 Aug 2004 13:01:36 GMT https://community.cisco.com/t5/network-security/microsoft-l2tp-connection-from-behind-pix/m-p/239804#M563241 scoclayton 2004-08-12T13:01:36Z Re: Microsoft L2TP connection from behind PIX https://community.cisco.com/t5/network-security/microsoft-l2tp-connection-from-behind-pix/m-p/239805#M563242 <HTML><HEAD></HEAD><BODY><P>there is a ms update that provides some nat-t support to l2tp, but i have no idea how effective it is. i believe it is a separate download for win2k and xp, and is included in xp sp2</P></BODY></HTML> Thu, 12 Aug 2004 14:39:37 GMT https://community.cisco.com/t5/network-security/microsoft-l2tp-connection-from-behind-pix/m-p/239805#M563242 mostiguy 2004-08-12T14:39:37Z