Solved: NAT query

d-g-c · ‎06-18-2008

Hi folks,

I have just established a RDP connection accross the internet between two pc's both running between ADSL connections.

When the connection is made, the firewall on the remote PC reports a connection from the NAT'd address of the local pc. However the Remote Desktop Clip Monitor is trying to make a connection to the "actual" IP address of the local machine - 10.4.82.101

I can't figure out why the machine would know about this address, since it is getting NAT'd.

Any suggestions would be much appreciated!!

Thanks

Jon Marshall · ‎06-18-2008

Peter

Sounds like the "real" IP address is being included in the data in the IP packet and this is what the RD Clip Monitor uses. So the IP header has the changed IP address but the real address is written into the actual data when the packet is transmitted.

This is why some applications do not work with NAT because NAT will only change the addresses in the IP header. Sometimes vendors have addtional code eg. fixup in pix firewalls, inspect on IOS routers that understand some of the more common application protocols and some of this code can cope with embedded NAT addresses.

Is this an inconvenience or is it stopping it working. It might be worth looking on vendor site for RD Clip Monitor and issues with NAT.

Jon

View solution in original post

Jon Marshall · ‎06-18-2008

Peter

Sounds like the "real" IP address is being included in the data in the IP packet and this is what the RD Clip Monitor uses. So the IP header has the changed IP address but the real address is written into the actual data when the packet is transmitted.

This is why some applications do not work with NAT because NAT will only change the addresses in the IP header. Sometimes vendors have addtional code eg. fixup in pix firewalls, inspect on IOS routers that understand some of the more common application protocols and some of this code can cope with embedded NAT addresses.

Is this an inconvenience or is it stopping it working. It might be worth looking on vendor site for RD Clip Monitor and issues with NAT.

Jon

d-g-c · ‎06-18-2008

Jon,

Thanks for the prompt reply. That's what i thought was probably happening, however i was starting to doubt myself!

Much appreciated.