Since weeks pingbacks and trackbacks didn't work (except getting trackbacks). Now, I found out, that I couldn't use the fopen() function for opening URLs in my own scripts, even with allow_url_fopen on enabled. I contacted my webspace provider and they told me, they disabled port 80 for security reasons. That's also the reason why the WordPress-dashboard doesn't show the RSS-feeds anymore. I could live with that, but not without having pingbacks and trackbacks.
Is there a workaround for sending trackbacks (using another port, another function or so...) and if so, where should I change what?