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New Member

Mapping outbound traffic to external IP.

I have couple of external IP addresses x.x.x.61 and x.x.x.69. I use the x.x.x.69 for NAT. My mail server (192.168.y.20:25) sits behind the firewall and is mapped to the external address x.x.x.61:25. There is no issue with incomming mail. The problem is that when mail is sent out the message appears as comming from x.x.x.69:25 and not from x.x.x.61:25. Some providers (e.g. Comcast) reject the mail based on the fact that the reverse look up does not match.

Is there a way to setup IOS to map outgoing traffic from 192.168.y.20:25 to x.x.x.61:25?

3 REPLIES
Hall of Fame Super Blue

Re: Mapping outbound traffic to external IP.

Hi

In IOS

ip nat inside source static tcp 192.168.y.20 25 x.x.x.61 25 extendable.

Just out if interest is it IOS you want to do this in or on the firewall ?

If the firewall is a pix then

static (inside,outside) tcp x.x.x.61 25 192.168.y.20 25 netmask 255.255.255.255

HTH

Jon

New Member

Re: Mapping outbound traffic to external IP.

Thanks for your quick reply.

I already have the "ip nat inside source...." command. The inbound traffic is routed just fine. It is the outbound traffic that keeps going out as x.x.x.69:25 since the x.x.x.69 is the external NAT IP. What I am looking for is to map the internal 192.168.y.20:25 to x.x.x.61:25

Re: Mapping outbound traffic to external IP.

Hi ..

If you are using a PIX, then you need to use static NAT instead of port forwarding meaning that you need to use.

static (inside,outside) public_IP Private_IP netmask 255.255.255.255

I hope it helps .. please rate if it does !!!

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