XMPP Handshake Failing

[Michael McConville]

On Tue, Jul 14, 2015 at 02:24:19PM -0400, J Kephart wrote:
> We're suddenly experiencing handshake failures when connecting via
> XMPP to our VoIP provider's service on uc.8x8.com--but only on
> Linux-based systems, such as Ubuntu. I've posted a typical debug log
> below:
> 
> (13:42:21) *jabber:* Recv (358): <?xml version="1.0" encoding="UTF-8"?><stream:stream xmlns="jabber:client" xmlns:stream="http://etherx.jabber.org/streams" from="uc.8x8.com" version="1.0" id="a13f3b0825cc44998ed98b0398b38893"><stream:features xmlns:stream="http://etherx.jabber.org/streams"><starttls xmlns="urn:ietf:params:xml:ns:xmpp-tls"><required></required></starttls></stream:features>
> (13:42:21) *jabber:* Sending (xxx at uc.8x8.com): <starttls xmlns='urn:ietf:params:xml:ns:xmpp-tls'/>
> (13:42:21) *jabber:* Recv (59): <proceed xmlns="urn:ietf:params:xml:ns:xmpp-tls"></proceed>
> (13:42:21) *nss:* Handshake failed  (-12156)
> (13:42:21) *connection:* Connection error on 0x7f0ffa07a170 (reason: 5 description: SSL Handshake Failed)

It's the TLS handshake failing. Has either the client or server software
been changed or updated recently? If not, my guess is that the server's
certificate expired.