ZyXEL Communications USG40 User Manual page 397

Even if you set a policy route to the same incoming interface and service as a HTTP redirect rule,
the ZyWALL/USG checks the HTTP redirect rules first and forwards HTTP traffic to a proxy server if
matched. You need to make sure there is no security policy(s) blocking the HTTP requests from the
client to the proxy server.
You also need to manually configure a policy route to forward the HTTP traffic from the proxy server
to the Internet. To make the example in
following settings.
For HTTP traffic between lan1 and dmz:
• a from LAN1 to DMZ security policy (default) to allow HTTP requests from lan1 to dmz.
Responses to this request are allowed automatically.
• a application patrol rule to allow HTTP traffic between lan1 and dmz.
• a HTTP redirect rule to forward HTTP traffic from lan1 to proxy server A.
For HTTP traffic between dmz and wan1:
• a from DMZ to WAN security policy (default) to allow HTTP requests from dmz to wan1.
Responses to these requests are allowed automatically.
• a application patrol rule to allow HTTP traffic between dmz and wan1.
• a policy route to forward HTTP traffic from proxy server A to the Internet.
SMTP
Simple Mail Transfer Protocol (SMTP) is the Internet's message transport standard. It controls the
sending of e-mail messages between servers. E-mail clients (also called e-mail applications) then
use mail server protocols such as POP (Post Office Protocol) or IMAP (Internet Message Access
Protocol) to retrieve e-mail. E-mail clients also generally use SMTP to send messages to a mail
server. The older POP2 requires SMTP for sending messages while the newer POP3 can be used with
or without it. This is why many e-mail applications require you to specify both the SMTP server and
the POP or IMAP server (even though they may actually be the same server).
SMTP Redirect, Firewall and Policy Route
With SMTP redirect, the relevant packet flow for SMTP traffic is:
Firewall
1
SMTP Redirect
2
Policy Route
3
Even if you set a policy route to the same incoming interface and service as a SMTP redirect rule,
the ZyWALL/USG checks the SMTP redirect rules first and forwards SMTP traffic to a SMTP server if
matched. You need to make sure there is no firewall rule(s) blocking the SMTP traffic from the client
to the SMTP server.
You also need to manually configure a policy route to forward the SMTP traffic from the SMTP server
to the Internet. To make the example in
following settings.
Chapter 14 Redirect Service
Figure 274 on page 395
Figure 275 on page 396
ZyWALL/USG Series User's Guide
397
work, make sure you have the
work, make sure you have the