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Webcast-Catalyst9k
New Member

IOS NAT ALG support for DNS using TCP

Hi,

I have been digging around on CCO for any documentation that describes if the DNS ALG in IOS NAT supports TCP based session (zone xfers, truncated responses).

I know the NAT ALG works nicely for UDP based DNS answers (DNS doctoring works) but with TCP it seems to silently ignore the DNS packet contents and not translate them.

Is TCP not supported?

Thanks alot,

S

2 REPLIES
Bronze

Re: IOS NAT ALG support for DNS using TCP

NAT-PT currently provides limited Application Layer Gateway (ALG) support. ALG support for Internet Control Message Protocol (ICMP), File Transfer Protocol (FTP), and Domain Naming System (DNS) is provided, and future Cisco IOS releases will have ALG support similar to NAT for other applications

http://www.cisco.com/univercd/cc/td/doc/product/software/ios123/123cgcr/ipv6_c/sa_natpt.htm

New Member

Re: IOS NAT ALG support for DNS using TCP

Thanks, but Im only using IPv4, not IPv6 so NAT-PT is not applicable.

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