We’ve just installed a new security certificate at jabber.org to replace the old one, which was due to expire on December 17. This new certificate should solve the recent connection problems experienced by users of Apple’s Snow Leopard operating system (OS X 10.6).
In other security news, our service will soon shut down the old SSL-only port 5223 because all IM clients should be able to upgrade port 5222 to a secure connection using the XMPP “STARTTLS” feature, which was standardized 5 years ago in RFC 3920. If your IM client was configured to prefer port 5223, you might need to adjust the configuration to use port 5222. (For improved security we would prefer to force the use of encrypted connections on port 5222, but won’t make that change until sometime in 2010.)