For other Movable Type blogs out there

If you're wondering why comments aren't working, as I was, and are on shared hosting, as I am, and get to looking at your error_log file and see something like this in it:

[Sun Oct 12 12:34:56 2014] [error] [client 192.0.2.5] 
ModSecurity: Access denied with code 406 (phase 2). 
Match of "beginsWith http://%{SERVER_NAME}/" against "MATCHED_VAR" required. 
[file "/etc/httpd/modsecurity.d/10_asl_rules.conf"] [line "1425"] [id "340503"] [rev "1"] 
[msg "Remote File Injection attempt in ARGS (/cgi-bin/mt4/mt-comments.cgi)"]
[severity "CRITICAL"] 
[hostname "example.com"] 
[uri "/cgi-bin/mt/mt-comments.cgi"]
[unique_id "PIMENTOCAKE"]

It's not just you.

It seems that some webhosts have a mod_security rule in place that bans submitting anything through "mt-comments.cgi". As this is the main way MT submits comments, this kind of breaks things. Happily, working around a rule like this is dead easy.

1. Rename your mt-comments.cgi file to something else
2. Add "CommentScript ${renamed file}" to your mt-config.cgi file

And suddenly comments start working again!

Except for Google, since they're deprecating OpenID support.