Date:  10 Jul 2014 02:34:29 Hong Kong Time

Firefox is not able to connect to a SOCKS-Proxy with IPv6



i do work since a little time in a new IPv6-only local network and there 
is a SOCKS5-Proxy for accessing the public/global Internet.

The SOCKS-Proxy is configured through a PAC-Script what can found by the 
"Web Proxy Autodiscovery Protocol" ( ). The 
PAC-Script is correctly found and read by Firefox (configured for 
autodetection the internet connection), even its HTTP-Server is also 
IPv6-only in the local network.

If i try a local server name then the PAC-Script returns "DIRECT" and 
Firefox do a local DNS-Query (that result is an AAAA-Record) and 
afterwards Firefox connect properly to the local server.
If i try a public server from the internet then the PAC-Script returns 
"SOCKS5 [Proxy-IPv6-Address]:Port" and Firefox do nothing, i can not see 
any TCP-Connection to the SOCKS5-Proxy with wireshark. When i set the 
"socks_remote_dns" to 'false' i see a DNS-Query to the local DNS-Server 
and its negative response but Firefox do also nothing to connect to the 

The only way for accessing the Internet with Firefox is to setup a local 
Proxy that is accessible by IPv4 (like "ssh -D") and 
configure it directly in the Firefox-GUI. This way disables the Features 
of the PAC-Script also.

All other Browsers, that i have tested, Chromium / Safari / Internet 
Explorer, are working correctly with configuration set to "autodetection 
the internet connection". As far as is see this Problem is present in 
_all_ Firefox versions on _all_ Platforms.

In my Opinion this is a major Bug in Firefox. In Bugzilla are multiple 
Bugs present for this Problem, but non of them are solved.

Is the support for SOCKS-Proxys not intended to be transitioned to IPv6?