Firewall Wizards mailing list archives
Re: NAT order help
From: "Avishai Wool" <yash () acm org>
Date: Mon, 12 Nov 2007 00:09:02 +0200
On 11/9/07, kevin horvath <kevin.horvath () gmail com> wrote:
first, AFAIK they are not in conflict since the translate-from address is different (10.0.0.0 != 1.1.1.2), so the order is irrelevant (?)they are. the access list for static pat stipulates the 10 net just as the static nat. Static nat wins over static pat.
well, actually, according to the cisco jargon at http://www.cisco.com/en/US/docs/security/asa/asa72/command/reference/s8_72.html#wp1202525 these are BOTH "static nat" - the 2nd one is regular old static nat and the 1st, with the access-list, is called "policy nat". to qualify for the term "static pat" you would need the extra "tcp" or "udp" keyword just after the (inside,outside).
second, I think they are processed in orderYou are thinking as if its an access list (permit or deny) but it works more like routing where the more specific statement wins if they are the same type of translation. Since they aren't and one is static nat then it has more precedence.
[snip - they are both the same type so I think the nat precedence rules you listed are not too relevant] I still say the statements seem non-conflicting, because the "mapped_ip" [the IP address right after the (inside,outside)] is different. Reading the Cisco docs, my understanding is that if a packet comes into the PIX with a ip.destination of "mapped_ip" (or in the "mapped_ip" subnet) then the pix translates that ip.destination to what the "static" command tells it to - namely the "real_ip" in regular static nat. in sivakumar's example. the mapped_ip is 1.1.1.2 in the 1st static, and 10.0.0.0 in the 2nd, so there is no conflict. Am I wrong? However, I am confused about one thing in the policy nat. here is the exaple: access-list rule1 permit tcp 10.0.0.0 255.0.0.0 host 1.1.1.1 static(inside,ouside) 1.1.1.2 access-list rule1 0 0 instead of just a real_ip subnet (as in the regular static), the access-list in fact has a subnet in the source field (10.0.0.0/8) and ANOTHER subnet in the destination field (1.1.1.1/32)... so when a packet comes into the PIX with ip.dest=1.1.1.2, how is it translated? using the source (10.0.0.0) or the destination (1.1.1.1) in the ACL? moreover, let's assume that the translate-to ip is the ACL's destination (1.1.1.1 in this example) - what does the OTHER (source) field do? Can any PIX mavens out there shed some light? PIXes are so weird. Avishai
On 11/6/07, sivakumar <siva_itech () yahoo com> wrote:Hi, access-list rule1 permit tcp 10.0.0.0 255.0.0.0 host 1.1.1.1 static(inside,ouside) 1.1.1.2 access-list rule1 0 0 static (inside,outside) 10.0.0.0 10.0.0.0 netmask 255.0.0.0 0 0 Please tell me which statement will take precedence - policy NAT ot Static NAT.. -- View this message in context: http://www.nabble.com/NAT-order-help-tf4737610.html#a13548213 Sent from the Firewall Wizards mailing list archive at Nabble.com. _______________________________________________ firewall-wizards mailing list firewall-wizards () listserv icsalabs com https://listserv.icsalabs.com/mailman/listinfo/firewall-wizards-- Avishai Wool, Ph.D., Co-founder and Chief Technical Officer http://www.algosec.com ******* Firewall Management Made Smarter ****** _______________________________________________ firewall-wizards mailing list firewall-wizards () listserv icsalabs com https://listserv.icsalabs.com/mailman/listinfo/firewall-wizards_______________________________________________ firewall-wizards mailing list firewall-wizards () listserv icsalabs com https://listserv.icsalabs.com/mailman/listinfo/firewall-wizards
-- Avishai Wool, Ph.D., Co-founder and Chief Technical Officer http://www.algosec.com ******* Firewall Management Made Smarter ****** _______________________________________________ firewall-wizards mailing list firewall-wizards () listserv icsalabs com https://listserv.icsalabs.com/mailman/listinfo/firewall-wizards
Current thread:
- NAT order help sivakumar (Nov 08)
- Re: NAT order help kevin horvath (Nov 09)
- Re: NAT order help Avishai Wool (Nov 09)
- Re: NAT order help kevin horvath (Nov 09)
- Re: NAT order help Avishai Wool (Nov 12)
- Re: NAT order help kevin horvath (Nov 13)
- Re: NAT order help sivakumar (Nov 14)
- Re: NAT order help kevin horvath (Nov 14)
- Re: NAT order help kevin horvath (Nov 09)