- There are two IP addresses on the server - internal ( 192.0.2.2 ) and public (203.0.113.2 ).
- The affected domain is assigned to the public IP.
tcpdumputility shows that requests to 80 (443) port are forwarded to internal IP instead of the public:
# tcpdump -pn -i any -vvA port 80
203.0.113.10.53338 > 192.0.2.2.80: Flags [.], cksum 0x9b8f (correct), seq 1647, ack 46057, win 254, length 0
If add the internal IP to webmail configuration file the webmail for affected domain opens correctly:
CONFIG_TEXT: less /etc/apache2/plesk.conf.d/webmails/plesk.test_webmail.conf
<VirtualHost 203.0.113.2:7080 127.0.0.1:7080 192.0.2.2.808:7080>
<VirtualHost 203.0.113.2:7081 127.0.0.1:7081 192.0.2.2.808:7081>
# /etc/init.d/apache2 reload
Routing misconfiguration on the server.
Configure requests via 80 (443) port to be forwarded correctly to public IP or delete internal IP from the network.