Recently on the Snort Mailing lists a request was made for the historical archive of the Snort code. So after pulling from several different areas I've assembled as much as I can (on a Friday) here:
There is a directory in there called "Old stuff you shouldn't use".
Seriously, you shouldn't use it. It's there for historical archive as requested.
I'll keep this up moving forward when there's a new release. Some versions missing in there, and I'm working to get those versions up as soon as possible. (Have to go to the backup tapes!)
Sourcefire/Snort/VRT's stance on support does not change, however. http://www.snort.org/vrt/rules/eol_policy These are the versions we support. We want people to upgrade because of features, bug fixes, and a plethora of other things. If you write in for support for an older version of Snort, we may be able to help you, but most likely you are going to be asked to Upgrade.
You simply would not believe the amount of requests we receive to troubleshoot stuff in older versions of Snort (like 2.3!?) Most likely, a problem in that old of a version of Snort has been fixed by now. Upgrade, Upgrade, Upgrade. I understand some of you have it baked into your routers and things like that. I know of routers/firewalls running 2.6. That version is about 7 years old now, and we just can't support every version.
The vast majority of our user base is around one version back (184.108.40.206) according to our download stats.
We think this is great. Our latest version, 220.127.116.11, fixes a ton of issues (like logging output of data), and introduces new features like flowbit OR'ing. 18.104.22.168 was released this week and contains some bug fixes and code cleanup that didn't make it into the 22.214.171.124 release.
So I encourage you to look through our archives and see how far we've come in 10+ years. The future is right around the corner, and it's brighter than ever.