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MS ISA & Cisco Pix Frontend / Backend Issues

Posted on 2009-05-19
Medium Priority
Last Modified: 2013-11-16

I am running in to a few problems with the setup of a frontend and backend FW setup. Ive had been trying to set this up in a test environment before I roll it out in a production environment.
        Ive ran in to a few problems. Ive set up the static NATs on the PIX to directly forward to the internal network. All traffic is routed on the ISA rather then NAT'ed to avoid a double nat.
     On the PIX I can ping computers on the internal network. However, I have a server in the perimeter network and I cant ping any computers on the internal network using the gateway. If I use the ISA as the gateway it works fine. However, I cant RDP in to it from an external IP etc...

On the internal network, all servers are able to get outside fine. Publishing RDP servers and OWA I am also running in to problems.

I have included the PIX config and a diagram of the network.

Any help would be greatly appreciated


PIX Version 6.3(5)
interface ethernet0 auto
interface ethernet1 auto
interface ethernet2 auto shutdown
nameif ethernet0 outside security0
nameif ethernet1 inside security100
nameif ethernet2 intf2 security4
enable password  encrypted
passwd  encrypted
hostname aam-pix
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
no fixup protocol smtp 25
fixup protocol sqlnet 1521
fixup protocol tftp 69
access-list 201 permit tcp any any eq www
access-list 201 permit ip any any
access-list 150 permit tcp any host 135.196.X.X eq https
access-list 150 permit tcp any host 135.196.X.X eq www
access-list 150 permit tcp any host 135.196.X.X eq smtp
access-list 150 permit tcp any host 135.196.X.X eq 3389
access-list 150 permit tcp any host 135.196.X.X eq ftp
access-list 150 permit udp any host 135.196.X.X eq isakmp
access-list 150 permit udp any host 135.196.X.X eq 4500
access-list 150 permit udp any host 135.196.X.X eq 10000
access-list 150 permit tcp any host 135.196.X.X eq 10000
access-list 101 permit ip
pager lines 24
logging on
logging timestamp
logging standby
logging trap informational
logging history warnings
logging host inside
mtu outside 1500
mtu inside 1500
mtu intf2 1500
ip address outside 135.196.X.X
ip address inside
no ip address intf2
ip audit info action alarm
ip audit attack action alarm
ip local pool ippool
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 pdm history enable
arp timeout 14400
global (outside) 1 interface
nat (inside) 0 access-list 101
nat (inside) 1 0 0
static (inside,outside) tcp interface ftp ftp netmask 0 0
static (inside,outside) tcp interface 3389 3389 netmask 0 0
static (inside,outside) tcp interface https https netmask 0 0
static (inside,outside) tcp interface www www netmask 0 0
access-group 150 in interface outside
access-group 201 in interface inside
route outside 1
route inside 1
route inside 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 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
aaa-server partnerauth protocol radius
aaa-server partnerauth max-failed-attempts 3
aaa-server partnerauth deadtime 10
aaa-server partnerauth (inside) host C1sco timeout 5
http server enable
no snmp-server location
no snmp-server contact
snmp-server community public
no snmp-server enable traps
floodguard enable
sysopt connection permit-ipsec
crypto ipsec transform-set myset esp-des esp-md5-hmac
crypto dynamic-map dynmap 10 set transform-set myset
crypto map mymap 10 ipsec-isakmp dynamic dynmap
crypto map mymap interface outside
isakmp enable outside
isakmp identity address
isakmp keepalive 10
isakmp nat-traversal 20
isakmp policy 10 authentication pre-share
isakmp policy 10 encryption des
isakmp policy 10 hash md5
isakmp policy 10 group 2
isakmp policy 10 lifetime 86400
vpngroup aam-vpn address-pool ippool
vpngroup aam-vpn dns-server
vpngroup aam-vpn default-domain aamtest.co.uk
vpngroup aam-vpn idle-time 1800
vpngroup aam-vpn password ********
telnet inside
telnet timeout 5
ssh timeout 5
console timeout 0
terminal width 255

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Question by:AAM_IT
  • 2
LVL 12

Accepted Solution

Amit Bhatnagar earned 2000 total points
ID: 24421834
What you are facing right now is a simple routing issue. If you will point to the Server in perimeter Network to Cisco, then it won't ping any internal Client unless you add a static route to it. This ofcourse starts working when you point the Server in Perimeter Network to ISA as ISA is already routing but then, any external request reaching the Server in Perimeter would also get redirected to ISA as the Default gateway is ISA.

Do this...Point the Server in Perimeter Network to CISCO as the Default Gateway. Add a static Route on the Server using Route Add command

Route add Mask -p

This command will make sure that even though the Default Gateway is set to CISCO, all the traffic which is meant for 192.168.0.X Network from the Perimeter Servers will always go to ISA.

Author Comment

ID: 24442836
Thanks chap :)

LVL 12

Expert Comment

by:Amit Bhatnagar
ID: 24451231
You are welcome !

Amit Bhatnagar :)

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