Securing Kerio Connect Multi-Server


This information is designed for Kerio Connect Multi-Server 9.

All servers in Kerio Connect Multi-Server communicate between them unsecurely. Therefore, run Kerio Connect Multi-Server in a dedicated private network protected with a firewall.

Firewall settings

This table shows the protocols and ports used in Kerio Connect Multi-Server.


Do not change these ports.

Refer to the table below and on your firewall, open the ports for the front-end server and instant messaging server.

Server Protocol Port
Syslog server UDP 514
Directory server LDAPLightweight Directory Access Protocol - A protocol that enables users to access centrally managed contacts. 389
Back-end servers IMAPInternet Message Access Protocol - One of the two most commonly used Internet standard protocols for e-mail retrieval, the other being POP3. 143
POP3Post Office Protocol 3 - A protocol used by local email clients to retrieve emails from mailboxes over a TCP/IP connection. 110
HTTPHypertext Transfer Protocol - A protocol for exchange of hypertext documents in HTML. 80
SMTPSimple Mail Transport Protocol - An internet standard used for email transmission across IP networks. 25
Kerio Connect Administration 4040
Instant messaging server XMPPExtensible Messaging and Presence Protocol is a protocol used for real-time communication (chat). 5222
XMPP SSLSecure Sockets Layer - A protocol that ensures integral and secure communication between networks. 5223
Session server memcached 11211
Distributed domain server Synchronization 44337
Free/Busy HTTP 80
Free/Busy HTTPSSecure version of secured by SSL. 443
User migration HTTPS 443
Front-end server IMAP 143
POP3 110
POP3 SSL 995
SMTP Submission 587
HTTP 80, 8800
HTTP SSL 443, 8843