I just bought an ASA 5505 that my data center is setting up for me. They have told me that setting the ASA to routed with NAT will break Web/DNS server on inside network.
For example: WAN IP 66.xxx.47.x translated to LAN IP 192.168.0.1 on inside network will not provide WAN IP to the inside Web/DNS server, which apparently will break DNS — of course DC provides no other details.
Are most people providing web services behind an ASA set in Transparent mode?? Looks like transient mode has some drawbacks, not terminating VPN traffic being one of them.
Seems like routed/NAT is the most secure/versatile, but maybe I’m not seeing the benefits of transient mode, on the surface, seems like a quick & dirty way to get up & running, hopefully more than that.
Feedback appreciated, I have to make the call on this soon…
A typical static entry looks like this:
static (inside,outside) 126.96.36.199 192.168.0.2 netmask 255.255.255.255
If they program it through ASDM, it’ll typically throw in the dns part. This alters DNS replies coming from the outside. This is NOT what you want:
static (inside,outside) 188.8.131.52 192.168.0.2 netmask 255.255.255.255 dns
Get rid of that DNS statement and you should be fine
Transparent mode is pretty nice, but it removes a bunch of features from the ASA. Go with routed mode unless you have a reason to do otherwise.
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