I have set up an SSL reverse proxy and found the net.ipv6.conf.all.disable_ipv6 bug (http://trac.nginx.org/nginx/ticket/552) is still biting us in v1.6.2. (I have installed Nginx through yum on CentOS).

ipv6 is disabled:
$ sysctl -a | fgrep disable_ipv6
net.ipv6.conf.all.disable_ipv6 = 1
net.ipv6.conf.default.disable_ipv6 = 1
net.ipv6.conf.lo.disable_ipv6 = 1
net.ipv6.conf.eth0.disable_ipv6 = 1

And we keep getting errors like:
2014/12/19 03:07:35 [error] 6392#0: *58764 connect() to [2607:f8b0:4001:c08::8d]:443 failed (101: Network is u
nreachable) while connecting to upstream, client: XX.XXX.XXX.XXX, ...

Is compiling from source without ipv6 option my only solution? If so, how can I make sure or varify that my build does not have ipv6 support?

Thanks.

If you don't want ipv6 why are you using ipv6 in your upstream?

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nginx for Windows http://nginx-win.ecsds.eu/

this is a bug as mentioned in the link above "The net.ipv6.conf.all.disable_ipv6 Linux sysctl support is implicit in nginx when it uses getaddrinfo() to resolve hostnames which it only does at configuration time. At run time, the built-in resolver is used which doesn't use getaddrinfo() and thus doesn't support Linux-specific sysctl."