Plesk firewall extension allows all connections but it was not configured in this way at Home > Extensions > Firewall .
# iptables-save | grep "-A INPUT -p udp -j ACCEPT"
/sbin/iptables -A INPUT -p udp -j ACCEPT
# iptables-save | grep "-A INPUT -p tcp -j ACCEPT"
/sbin/iptables -A INPUT -p tcp -j ACCEPT
This is a software issue with internal ID PPPM-714 . Fixed in
Plesk 11.5 .
If there is no possibility to do it right now, you can apply workaround:
Create database backups according to article KB213904125
Remove these lines from
mysql> delete from module_firewall_rules where object like '%neigh%';
Query OK, 2 rows affected (0.01 sec)