Linux Squid Proxy server access to Google error

Linode VPS, using squid to build a proxy, after loading, found that Facebook can be on, YouTube can also, but Google prompted errors, as follows

We ' re sorry ... but your computer or network may is sending automated. To protect we are users, we can ' t process your request right now

Looking for a long time on the internet, finally found a solution.

Method One: Edit/etc/sysctl.conf, add the following

Net.ipv6.conf.all.disable_ipv6=1
Net.ipv6.conf.default.disable_ipv6=1
Net.ipv6.conf.lo.disable_ipv6=1
Reboot network card

#/etc/init.d/networking Restart

Method two, immediate effect

echo ' 1 ' >/proc/sys/net/ipv6/conf/lo/disable_ipv6
echo ' 1 ' >/proc/sys/net/ipv6/conf/lo/disable_ipv6
echo ' 1 ' >/proc/sys/net/ipv6/conf/all/disable_ipv6
echo ' 1 ' >/proc/sys/net/ipv6/conf/default/disable_ipv6