topic policy nat address pool in Network Security

policy nat address pool

mickyq — Tue, 12 Mar 2019 01:06:44 GMT

I have an internal firewall between two private networks.

I want all addrssing on the inside to use the gobal and I want any internal address destined for a group of servers on port 23 on the external to use a pool of addreses

the inside network is 10.0.0.0/8 and the destination subnet is 10.130.29.0/25. routes exist and connectivity works

heres the config

global (outside) 1 10.130.29.2

nat (inside) 1 access-list nat

access-list nat deny ip host 10.7.2.206 any

access-list nat deny ip host 10.7.2.207 any

access-list nat permit ip any any

ive added:

object-group network SERVERS

network-object host 195.104.88.151

network-object host 195.104.88.152

network-object host 195.104.88.153

access-list serv_acl permit tcp 10.0.0.0 255.0.0.0 object-group SERVERS eq 23

global (outside) 2 10.130.29.117-10.130.29.126 netmask 255.255.255.128

nat (inside) 2 access-list serv_acl

the SERVERS are destined for another network byond the firewall but I need to translate any address from the internal to pool 2. I can connect using the global but after applying the added config above the connection is still using the global. the xlate was cleared.

Is the subnet mask correct for the pool?

any help appreciated.

policy nat address pool

Jouni Forss — Wed, 27 Feb 2013 17:19:42 GMT

Hi,

So you say that your traffic is hitting the original Dynamic Policy PAT rule after configuring the new Dynamic Policy NAT rule?

I think this is because of the NAT ordering.

I am not sure if the "ID" of the NAT configuration has any meaning but I would try changing the NAT configuration in the following way

no global (outside) 1 10.130.29.2

no nat (inside) 1 access-list nat

global (outside) 100 10.130.29.2

nat (inside) 100 access-list nat

Then perhaps "clear xlate" if situation permits.

This should do so that the new Dynamic Policy NAT rule is the first to be matched and the original rule comes after that.

Notice that the original rule has a "permit ip any any" ACL rule which matches all traffic. So everything gets matched to it and wont get matched to the new rule.

Can you try this out and see how it goes.

- Jouni

policy nat address pool

mickyq — Thu, 28 Feb 2013 18:22:38 GMT

Thanks Jouni

You were exactly right.

The first policy had 'ip any any' which of course catches all traffic . I change the order and it works fine.

Thanks again

michael