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Configuration Example Most Basic Zone Based Firewall

Posted on 2008-10-10
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Last Modified: 2012-05-05
I have some remote SOHO routers VPNing to a central site.  I want to add a very basic Zone Based Policy Firewall such that all traffic to the Internet is permitted out and its reply traffic is permitted in.  Inbound SIP traffic from two hosts is peritted in and IPSEC traffic is permitted from specific IP.  ICMP is permitted any any.  Would appreciate a configuration example.  Thanks.
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Question by:amigan_99
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by:Pugglewuggle
ID: 22693151
I highly recommend the Cisco ASA 5505 - this firewall is indeed zone-based and supports SIP as well as IPsec and SSL VPN. The unit runs about $350 USD and will do everything you need! It will work fine with an 871 router as well regarding the VPN.
http://www.cisco.com/en/US/prod/collateral/vpndevc/ps6032/ps6094/ps6120/product_data_sheet0900aecd802930c5.html
Cheers! Let me know if you have any questions
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by:Pugglewuggle
ID: 22693153
Also - it supports all Cisco LAN routing protocols - EIGRP, OSPF, RIP.
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by:kyleb84
ID: 22699936
A Very basic example of this would be just to create a few ACLs:

This is just off the top of my head and would probably work.
- The config assumes your internal network is 192.168.1.0/24
- Also, the permit gre ACLs are still in place for the IPSEC.

At least you've got something to base your config on...

!
int Dialer 0
 ip access-group 110 in
!
! Allow SIP from hosts x.x.x.x, and y.y.y.y, deny the rest
access-list 110 permit tcp host x.x.x.x  any eq 5060
access-list 110 permit tcp host y.y.y.y  any eq 5060
access-list 110 deny tcp any 192.168.1.0 0.0.0.255 eq 5060
!
! IPSEC allow
access-list 110 permit tcp z.z.z.z 0.0.0.0 any eq 500
access-list 110 deny tcp any 192.168.1.0 0.0.0.255 eq 500
!
! ICMP
access-list 110 permit icmp any any
!
! And allow existing NAT TCP streams
access-list 110 permit tcp any any established
!
! DENY the rest
access-list 110 deny any any
!
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by:amigan_99
ID: 22699945
Thanks for the ACL method.  But I specifically want the ZBPF so that all the return traffic is intelligently permitted back in.  
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kyleb84 earned 500 total points
ID: 22699972
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Author Closing Comment

by:amigan_99
ID: 31505147
I was looking specifically for a minimalist configuration.  But this is the best answer.  Thanks.
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by:Pugglewuggle
ID: 22703963
The ASA/PIX will automatically permit all return traffic.
On Cisco routers, you must use the keyword "established" at the end of all TCP ACLs, like this:
access-list 110 permit tcp host y.y.y.y any eq 5060 established
Cheers! Let me know if you have any questions!
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