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Community Member

proper config for 515 routing outbound

I just got our new 515E into the shop and I've been trying to get it up and running. This is my first experience with PIX, so I've definitely drifted a little deeper in the pool than I've been before.

We have a subnetted class C that we'd like to hold on to, since all the machines are presently configured with it. I'm not interested in NAT and using private addresses behind the PIX since that is the case. I can't seem to get the unit configured, though, in such a way that it let's me access outside from inside.

Using the example here:

I managed to work up the following config:

PIX Version 6.3(1)

interface ethernet0 auto

interface ethernet1 auto

nameif ethernet0 outside security0

nameif ethernet1 inside security100

enable password xxxx

passwd xxxx

hostname pixfirewall


fixup protocol ftp 21

fixup protocol h323 h225 1720

fixup protocol h323 ras 1718-1719

fixup protocol http 80

fixup protocol ils 389

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


access-list acl_out permit icmp any any

pager lines 24

logging buffered debugging

mtu outside 1500

mtu inside 1500

ip address outside A.B.C.130

ip address inside A.B.C.193

ip audit info action alarm

ip audit attack action alarm

arp timeout 14400

nat (inside) 0 A.B.C.130 0 0

access-group acl_out in interface outside

route outside A.B.C.129 1

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 uauth 0:05:00 absolute

aaa-server TACACS+ protocol tacacs+

aaa-server RADIUS protocol radius

aaa-server LOCAL protocol local

http server enable

http A.B.C.200 inside

floodguard enable

telnet timeout 5

console timeout 0

terminal width 80

I can ping the router (outside) from the PIX, and I can ping hosts on my network (inside) from the PIX, and vice versa. I can't seem to transverse it, though, with ping or http requests.

Anyone see the problem with my configuration?




Re: proper config for 515 routing outbound

the pix is not a bridging firewall. you have both your outside and inside interfaces on the same subnet, which will not work. you will likely need to use your legit ip addresses on the outside, and use nat internally.

how many hosts do you have inside?

Community Member

Re: proper config for 515 routing outbound

Two things...

1. I really don't see why I'd have to change all the hosts inside to a private IP. I don't understand how my situation is different from the example in the documentation that I linked to.

2. I don't really have both my outside and inside interfaces on the same subnet. They both use the same class C, but with a subnet mask of they're on different subnets (inside is on A.B.C.192 and outside on A.B.C.128).

Am I missing something?

- CW


Re: proper config for 515 routing outbound

i lost my head, you are right on the ip addressing

edit : don't you want to disable nat?

nat 0 a.b.c.192 woul do identity nat for the inside subnet. this would allow those hosts to avoid nat, and make connections outbound, and thus create xlates. xlates would not be automatically created for outside hosts to initiate commo to inside hosts. to do that, nat 0 access... or a static command would be necessary

Community Member

Re: proper config for 515 routing outbound

Hmmm...I have a curiosity question here.

Assuming I have the PIX configured properly for untranslated addresses on the inside, when those packets move across the PIX out the outside interface...what would happen to them? They'd be on a different subnet than they originated from, wouldn't they? And without translation, no device configured on the OUTSIDE subnet (including the outer router) would be able to pick up those packets, no?

If this is the case, what good is bypassnig NAT to use public IPs...if they have to be on a different subnet, and one that isn't going to be routed on the other side? Is there something in the router config that picks up those requests and sends them along?

- CW

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