Every few minutes our Cisco ASA 5505 firewall is logging errors that I can't figure out with my limited Cisco experience.
Severity Date Time Syslog ID Source IP Destination IP Description 3 Mar 25 2010 17:21:14 305006 18.104.22.168 regular translation creation failed for icmp src inside:10.10.0.206 dst outside:22.214.171.124 (type 3, code 3) 3 Mar 25 2010 17:18:37 305006 126.96.36.199 regular translation creation failed for icmp src inside:10.10.0.206 dst outside:188.8.131.52 (type 3, code 3)
The logged inside-IP is our internal DNS server, and the outside IP's are Google's public DNS servers, which we're using as forwarders in our local BIND config. ICMP Type 3 Code 3 means "Port Unreachable".
The 'Inspect DNS', 'Inspect ICMP' and 'Inspect ICMP Errors' global Service Policies are enabled, with the default inspection maps.
Our "outside" interface has a fixed IP and our "inside" interface is in the 10.10.0.0/16 subnet. The 10.10.0.206 IP is our internal BIND DNS server, and DNS is resolving fine. Using different DNS forwarders, such as OpenDNS, generates the same errors.
I've spent days trying to figure this one out, so any and all advice is appreciated!