I have an Cisco 871 at a remote site and at the head end I have a Checkpoint Firewall; I can get the tunnel to come up and everything seems to work okay except for Outlook to Exchange server and File Mappings basically anything using AD Authentication. I took out the 871 and replaced it with a PIX501 and everything works perfectly. I also tried 2 different 871's with the same results so I am guessing I am missing some type of command in the 871 to fix this but I can't seem to figure out what it is. Anyone else ever have this problem and can you share the resolution please? I have attached my sample configs of the PIX and 871.