After months of receiving spam through my contact forms I decided it was time to add reCAPTCHA to them in the hope of stemming the tide of garbage. This now under the control of Google I thought there wasn't going to be an issue with this. Having just installed reCAPTCHA on my works websites I knew what to do and all went well on those sites. On the Friday I did 3 forms on my own sites and all worked as expected, on the Saturday I did the last form I had, but that one didn't work. All I kept getting was a 'could not open socket' error.

Initially I thought I must have made some error in the code but after checking the code against that which I had done the day before I could see no error. And more over the 3 forms I did the day before that worked, now no longer worked and displayed the same error message, what the hell?? Most frustrating was the fact that this was all the message said and gave no clue as to what was causing it. I made a number of attempts to find which section of code that was at fault by adding echo's throughout the php code but none of them showed, only that damned error message. I thought there must be something wrong with the server.

Someone must have had this issue before so I turned my attention to Google for an answer. As I started to type 'could not open socket' the autocomplete came up with 'could not open socket recaptcha', ah ha! But I couldn't think why it could have worked yesterday and not today? After reading many unhelpful posts' I found this: http://code.google.com/p/recaptcha/issues/detail?id=26 which although didn't have the exact answer it did help me to realise the answers to my own issues.

After reading through this thread I came to the conclusion that my problem was 2 fold and explained why it had worked yesterday and not today. The main problem was my web host, in their attempt to be helpful they introduced (a long time back) blocking of outgoing connections to remote IPs from within my sites. This is one to be aware of if you are auto blogging using wp-o-matic, any feed you add will most likely be blocked by this until you add the IP to the allowed list from within your control panel.

I assume there is a good reason for them doing this but it can imagine it has caused nightmares for the inexperienced. Obviously it had worked yesterday because it was new, once the server knew the connection was being made it blocked it. It was probably the number of tests I did that made the connection get noticed and was possibly a good job it was noticed so quickly or I might not have noticed it for some time.

So which IP was I to add to the allowed list? The line of code in recaptchalib.php identified as the problem in the above thread was:

define("RECAPTCHA_VERIFY_SERVER", www.google.com);

So what I needed was the IP of google.com. http://www.mxtoolbox.com/SuperTool.aspx is a very useful tool I have been using for a long time. A DNS lookup for google.com gave me 5 options for an IP, 74.125.227.48 to 74.125.227.52, so now I have:

define("RECAPTCHA_VERIFY_SERVER", "74.125.227.48");

Adding this IP to the allowed remote IP list from within my control panel sorted the problem on all my forms. Score!