howto use PIX as transparent firewall, no NAT, just traffic monitoring

Hello all
i have PIX 525, and i want to place it infront of my ISP network. Currently the 7500 router is facing the external network. I want to configure PIX transparently , ie not configure NAT for my internal IP's and use PIX just to monitor all of the traffic coming to my corporate network and allow specific traffic for web, ftp and mail machines. Anybody guide me in this regards, i also tried to search some scenarios to get help for this but not scenarios found, please send me some link or guide me in this regards.also guide me that is it recommended to place it infront of the network ????
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Tim HolmanCommented:
Try setting up two access lists, so keep 101 for outside > in -

access-list 101 permit tcp any host x.y.z.a eq telnet
access-list 101 permit tcp any host x.y.z.a eq domain
access-list 101 permit tcp any host x.y.z.a eq ssh
access-list 101 permit tcp any host x.y.z.a eq www
access-list 101 permit udp any any eq domain
access-list 101 permit icmp any host x.y.z.a
access-list 101 permit tcp any any
access-list 101 permit icmp any any

...but have a separate one for inside > out

access-list 102 permit ip any any

..then apply as follows:

access-group 101 in interface outside
access-group 102 in interface inside

And remove the NAT:

no static (inside,outside) netmask 0 0

This way, as long as addresses are fully routable on either side.

This way, the PIX will just firewall the IP addresses, rather than NATting.

Tim HolmanCommented:
You can't configure the PIX transparently (ie layer 2).  It NEEDS IP addreses.
I believe transparency will be addressed in a later release of software.
ahsan9211110200Author Commented:
but we can assign IP addres to the outside interface of the firewall then what's the problem in using it as transparent ????????


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ahsan9211110200Author Commented:
hello all
i can't find the satisfied answer of my question, so i have now changed my firewall behaviour. Now i have placed my firewall behind transit router. now i m getting a problem. traffice from my external interface to internal interface is Ok according to the access list, and inside to outside is also fine, but when i tried to pass the traffic throug hmain router ,  it is not working fine, plz tel me know , wat to do now ??????

Tim HolmanCommented:
PIX is a firewall, not a router ?

What do you mean by transparent - do you mean like a layer 2 switch is ?

ahsan9211110200Author Commented:

now i want just monitoring. i m placing it inside my network. i have applied accesslist to allow http, ftp , SMTP and pop request from outside to my inside interface, but when i request from outside for http or request for http from inside, it's not working, i m pasting the running config, here

: Saved
PIX Version 6.3(3)
nameif ethernet0 outside security0
nameif ethernet1 inside security100
hostname pixfirewall
domain-name asia.pix
clock timezone PKT 5
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
access-list 101 permit tcp any host x.y.z.a eq telnet
access-list 101 permit tcp any host x.y.z.a eq domain
access-list 101 permit tcp any host x.y.z.a eq ssh
access-list 101 permit tcp any host x.y.z.a eq www
access-list 101 permit udp any any eq domain
access-list 101 permit icmp any host x.y.z.a
access-list 101 permit tcp any any
access-list 101 permit icmp any any
access-list acl_in permit tcp any host x.y.z.a eq ssh
pager lines 20
logging on
logging trap notifications
logging device-id ipaddress inside
logging host inside x.y.z.a
icmp permit any outside
icmp permit any inside
icmp deny any intf2
mtu outside 1500
mtu inside 1500
mtu intf2 1500
mtu intf3 1500
ip address outside x.y.z.a   x.y.z.a
ip address inside x.y.z.a   x.y.z.a
no ip address intf2
no ip address intf3
ip audit info action alarm
ip audit attack action alarm
no failover
failover timeout 0:00:00
failover poll 15
no failover ip address outside
no failover ip address inside
no failover ip address intf2
no failover ip address intf3
pdm location x.y.z.a x.y.z.a  inside
pdm history enable
arp timeout 14400
static (inside,outside) netmask 0 0
access-group 101 in interface outside
access-group 101 in interface inside
route outside 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 x.y.z.a inside
snmp-server host inside x.y.z.a
no snmp-server location
snmp-server contact waseem
snmp-server community Pix@Asia
no snmp-server enable traps
tftp-server inside x.y.z.a /source
floodguard enable
sysopt connection permit-pptp
telnet a.b.c.d inside
telnet timeout 30
ssh a.b.c.d inside
ssh timeout 50
management-access inside
console timeout 60
terminal width 80
banner motd Speed
: end

i have removed unrelated lines

waiting for the answerr


Tim HolmanCommented:
To go from outside in, you need static NAT, plus the access lists.
I can see static NAT for - if this is x.y.z.a then you're on the right track.
BUT, as you've only two interfaces, you can't do identity NAT ( to
ahsan9211110200Author Commented:

but both of the ourside and inside network have different net ID's. and i m using NAT x x just for that i don't wannt to do natting, ie on the inside i have the machines with live IP's and i don't want NAT on the PIX so i just do NAT X X ,
i can't understand where my trafic is lagging , i m also using syslog, but no success

Tim HolmanCommented:
Config guide here:

I understand what you need now - and yes, it is possible if there are different net IDs on either side.
ahsan9211110200Author Commented:
thanx but i have alreay gone through these articles but my problem is still not solved.
my configuration is given above and i think that everything is fine but still its creating problem. plz read the above config and advise me that what may be the problem .
Tim HolmanCommented:
You need static NAT in order to get from the outside to the inside.
If you want more details, then you will need to post up more points..  ;)
ahsan9211110200Author Commented:
i think this is very basic question and not needed any more points.
just a global statement and a static statement needed, but ok if u want this ,
i m adding 50 more points, now waiting for the answer

than  in advance
ahsan9211110200Author Commented:
still no response,
i'll wait for last1week then i'll close the question
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