User`s guide

Chapter 1 Introduction

A public server can be as the following example:

company.com MX 10 mail.company.com

mail.company.com A 215.75.128.33

You should also set a record for your backup mail server, if you have one available.

Firewall conﬁguration

Kerio Connect is installed in a local network behind a ﬁrewall. In addition to the mailserver’s

conﬁguration, it is also necessary to perform corresponding additional settings of the ﬁrewall.

If the mailserver is to be accessible from the Internet, certain ports have to be opened (mapped)

in the ﬁrewall. Each mapped port might introduce security problems. Therefore, map ports

only for those services which you want to make available from the Internet.

In the case of our network environment, it is necessary to map port 25 (a default port for the

SMTP service). This setting is required for cases where an MX record for the particular domain

is addressed to the server. Any SMTP server on the Internet can connect to your SMTP server

to send email to one of its domains. For this reason access to the mapped port 25 must not

be restricted to particular IP addresses.

Now, it is necessary to map ports that will be used for connections out of the local network.

Since the security risk is higher here, only SSL/TLS-secured services will be mapped. Settings

are shown in table 1.1.

Service (default port) Outgoing connection Incoming connection

SMTP (25) allow allow

SMTPS (465) allow allow

POP3 (110) allow deny

POP3S (995) allow allow

IMAP (143) allow deny

IMAPS (993) allow allow

NNTP (119) allow deny

NNTPS (563) allow allow

LDAP (389) allow deny

LDAPS (636) allow allow

HTTP (80) allow deny

HTTPS (443) allow allow

Table 1.1 Services to be allowed on the ﬁrewall