Squid keeps listening on IPv6 and gives slow access to its client.

Issue

• Squid keeps listening on IPv6 and gives a 5-second delay based on the default value of the 'dns_retransmit_interval' to its client in accessing internet even when sysctl shows IPv6 is disabled.

The below sysctl command shows IPv6 is disabled as follows.

# sysctl -a
net.ipv6.conf.default.disable_ipv6 = 1
net.ipv6.conf.all.disable_ipv6 = 1

The below ss command shows squid still listens on IPv6 on tcp 3128 port.

# ss -tulpn | grep squid
tcp    LISTEN     0      128      :::3128                 :::*                   users:(("squid",pid=3095,fd=11))

• After that sysctl shows IPv6 is disabled, we get the following message when we run the "squid -k check" command.

# squid -k check
WARNING: BCP 177 violation. Detected non-functional IPv6 loopback.