Cisco Cisco Email Security Appliance C160 Guide De Montage

Depending on your network configuration, your firewall may 
need to be configured to allow access using the following ports. 
SMTP and DNS services must have access to the Internet. 

DNS: port 53

SMTP: port 25

For other system functions, the following services may be 
required:

FTP: port 21, data port TCP 1024 and higher

HTTP: port 80

HTTPS: port 443

LDAP: port 389 or 3268

LDAP over SSL: port 636

LDAP with SSL for global catalog queries: port 3269

NTP: port 123

SSH: port 22

Telnet: port 23

If you do not open port 80 and port 443, you cannot 
download feature keys.

For more information, see firewall information in the user guide 
for your version of AsyncOS for Cisco Email Security 
Appliances.