So, I needed a fast way to install dovecot on a centos 7 server in a private network that had access to my own network but not to the internet.

I set up a proxy and then saw that yum wants to use ipv6 here’s what I did

export http_proxy="http://198.51.100.13:3128"
echo 'ip_resolve=4'>> /etc/yum.conf
sysctl -w net.ipv6.conf.all.disable_ipv6=1
sysctl -w net.ipv6.conf.default.disable_ipv6=1
yum update