Please help with port forwarding problem!!!

[markjrees]

Can anyone give us some help?

We are trying to configure input filters on our NAT server so that all SMTP traffic is forwarded to an Exchange server but a slight problem occurs.

When we specify the IP address of the Exchange server it requires a Subnet Mask to be entered also, but it will not accept the subnet 255.255.255.0 that we are using throughout the network. If we use a subnet of 0.0.0.0 as per MS instructions it says that the "Destination address cannot be more specific than the network mask"

Any help is appreciated.

Luke.

http://www.accountantjokes.co.uk

http://www.markjrees.co.uk

http://www.mjrcomputersolutions.co.uk

http://www.mjrfm.co.uk

 

[Parcival21]

Well I'm not that deep in this topic but i might help you.
I know that cisco uses a wildcard mask for some commands.
This wildcard mask differs in the following way from the subnet mask.
If you have a subnet mask of 255.255.255.0 it changes to 0.0.0.255.
To talk binary, The ones are exchanged by zeroes and the zeros are exchanged by ones.
You might try it this way.Hope this helps,
busche

 

[Nettekkie1010]

Parcival21 is correct. Cisco access-lists definately use the wildcard mask when specifying an IP address.

172.18.20.0 255.255.255.0 would be 172.18.20.0 0.0.0.255
10.16.4.0 255.255.252.0 would be 10.16.4.0 0.0.3.255
and so on....

In your case enter it as <your IP address> 0.0.0.255