Cisco Feature Navigator equivalent for ASA's? I've recently been using the Cisco Feature Navigator to assess whether or not to upgrade IOS images (and compare them), but it doesn't support ASA software. Is there an easy way to compare images for ASA's like with CFN? If not, how do you do this without manually combing release notes?

The feature set of the ASA changes so very rarely, it's not something Cisco has ever put any effort into creating. The few changes that have occurred are between major revisions, eg.

* 8.2 to 8.3 -> major nat configuration change
* somewhere in the v7 era "hair-pinning" became possible
* SSLVPN (webvpn) [v7+]
* IPv6 support (the joke that it is)
* transparent mode



(I'm sure there's more, but that all I can think of!)

The command reference generally tells in which versions it's valid.

The only reason I've updated any over the last ~5 years is security bug fixes.