Re: Outside NAT with PIX

tgrundbacher · ‎09-14-2005

I'm having a problem when working with outside NAT. Maybe I haven't understood the concept of outside NAT properly.

Here's the lab situation:

Running PIX OS 6.3(3) and (5).

outside network: 192.168.0.0 /24

inside network: 10.0.0.0 /8

A customer has an inside host 10.0.0.2 statically NATted to the outside global of 20.0.0.2. So far so good, traffic flows correctly with the related access-lists.

What the customer now wants is, for initiated inbound traffic, to do inbound PAT and source translate every IP to a global of 30.0.0.3 (we're talking of outside NAT). After having done that, traffic flows can be established from any outside host to our inside host, on which we see that sessions will originate from 30.0.0.3.

The problem now: I can't initiate outbound traffic anymore, with the following log entry in the PIX log:

305005: No translation group found for tcp src inside:10.0.0.2/11009 dst outside:192.168.

0.2/8080

Why is that? We do have a static (inside,outside) that should be dealing with the translation, isn't it?

Any help is appreciated!! See the config below.

Thanks

Toni

---

pixfirewall(config)# sh run

: Saved

:

PIX Version 6.3(5)

interface ethernet0 auto

interface ethernet1 auto

nameif ethernet0 outside security0

nameif ethernet1 inside security100

enable password xxx

passwd xxx

hostname pixfirewall

fixup protocol dns maximum-length 512

fixup protocol ftp 21

fixup protocol h323 h225 1720

fixup protocol h323 ras 1718-1719

fixup protocol http 80

fixup protocol rsh 514

fixup protocol rtsp 554

fixup protocol sip 5060

fixup protocol sip udp 5060

fixup protocol skinny 2000

fixup protocol smtp 25

fixup protocol sqlnet 1521

fixup protocol tftp 69

names

access-list outside permit ip any host 20.0.0.2

access-list outside permit icmp any any

access-list inside permit icmp any any

access-list inside permit tcp any any eq 8080

access-list inside permit ip any any

access-list nat-outside permit ip any host 20.0.0.2

pager lines 24

logging on

logging buffered debugging

mtu outside 1500

mtu inside 1500

ip address outside 192.168.0.1 255.255.255.0

ip address inside 10.0.0.1 255.0.0.0

ip audit info action alarm

ip audit attack action alarm

pdm history enable

arp timeout 14400

global (inside) 1 30.0.0.3

nat (outside) 1 access-list nat-outside outside 0 0

static (inside,outside) 20.0.0.2 10.0.0.2 netmask 255.255.255.255 0 0

access-group outside in interface outside

access-group inside in interface inside

timeout xlate 3:00:00

timeout conn 1:00:00 half-closed 0:10:00 udp 0:02:00 rpc 0:10:00 h225 1:00:00

timeout h323 0:05:00 mgcp 0:05:00 sip 0:30:00 sip_media 0:02:00

timeout sip-disconnect 0:02:00 sip-invite 0:03:00

timeout uauth 0:05:00 absolute

aaa-server TACACS+ protocol tacacs+

aaa-server TACACS+ max-failed-attempts 3

aaa-server TACACS+ deadtime 10

aaa-server RADIUS protocol radius

aaa-server RADIUS max-failed-attempts 3

aaa-server RADIUS deadtime 10

aaa-server LOCAL protocol local

no snmp-server location

no snmp-server contact

snmp-server community public

no snmp-server enable traps

tftp-server outside 192.168.0.2 /

floodguard enable

telnet timeout 5

ssh timeout 5

console timeout 0

terminal width 80

Cryptochecksum:xxx

: end

pixfirewall(config)#

owillins · ‎09-20-2005

%PIX-3-305005: No translation group found for protocol src: message signals a configuration error. If dynamic NAT is desired for the source host, ensure that the nat command matches the source IP address. If static NAT is desired for the source host, ensure that the local IP address of the static command matches. If no NAT is desired for the source host, check the ACL bound to the nat 0 ACL.

jackko · ‎09-20-2005

according to the config above, there is no outside nat statement

access-list nat-outside permit ip any host 20.0.0.2

global (inside) 1 30.0.0.3

nat (outside) 1 access-list nat-outside outside 0 0

with these statements, the pix will nat any packet has a destination to 20.0.0.2 into 30.0.0.3. traffic with other destinations will not match the acl and that mean will not be natted. that's why no traffic can be initiated outbound. the only exception is 10.0.0.2 as it will be natted to 20.0.0.2

in order to achieve the outside nat, try

static (outside,inside) 30.0.0.3 netmask 255.255.255.255 0 0

howeever, it may not be feasible to do outside pat, i did only 1-to-1 nat

dritanulqinaku · ‎09-23-2005

I have the same problem of outside. So I want to do a nat 1-to-1 translation. I have excecuted the:

When I executed:

static (outside,inside) 30.0.0.3 real_ip_lan netmask 255.255.255.255 0 0

I have seen that I can see the web site from inside with domain name but I can not see it from outside.

I have used an access-list:

access-list www permit tcp any host 30.0.0.3 eq www

and access-group www in interface outside

can you please help me?

thnx

tgrundbacher · ‎09-23-2005

Hi dritanulqinaku

I'm not quite sure of what you want to do. Can you tell us how you want to translate and in which direction you want to filter?

I interpret your config output this way:

- You want to translate the destination IP for a host sitting on the outside. Seen from the inside.

- Confusingly, you want to only permit www traffic coming from any host sitting on the outside to 30.0.0.3, which in turn is only accessible from the inside?

I think you need to bind the access-list to the inside interface:

access-group www in interface inside

Hope this helps...

Toni

jackko · ‎09-23-2005

hi dritanulqinaku,

are you trying to setup a web server located behind the firewall and allowing access from the internet? if so, you'll need the followings:

static (outside,inside) netmask 255.255.255.255

plus the acl you've got already

tgrundbacher · ‎09-23-2005

Thanks for your reply, jackko.

Some things to point out:

- I'm aware that there is no nat (inside) 0 0.0.0.0 0.0.0.0 statement in my config. Yet, I've used it during the lab with no success.

- Your statement: "traffic with other destinations will not match the acl and that mean will not be natted" does only apply to inbound traffic. Yes, traffic won't be translated for initiated outbound connections from any to any as well, but this is due to the missing nat (inside) 0 statement. According to the tests in my lab, it won't change the problem if you entered it.

- I agree, the only exception that should be translated is 10.0.0.2 as it will be natted to 20.0.0.2. The thing is: it doesn't. See the error message I've already posted:

--> 305005: No translation group found for tcp src inside:10.0.0.2/11009 dst outside:192.168.

0.2/8080

- This error msg was generated while I Pinged from that mentioned source 10.0.0.2 to an outside host. Representing the reason for my confusion and this post.

I'd really be glad if someone could confirm the capability of the PIX to handle this kind of NAT. By now, no one could really prove it works.

jackko · ‎09-23-2005

just wondering if you did "clear xlate" as it's required when modifying any nat-related statement.

also do a "show xlate" and "debug icmp t" to verify whether the pix does perform the nat as expected as well as whether or not the traffic is being sent and received.