ZyXEL Communications ZyWALL USG100-Plus User Manual page 112

Chapter 5 Managing Traffic
5.6.2.4 Set Up a DMZ to LAN Firewall Rule for SIP
The firewall blocks traffic from the DMZ zone to the LAN1 zone by default so you need to create a
firewall rule to allow the IPPBX to send SIP traffic to the SIP clients on the LAN.
Click Configuration > Firewall > Add. Set the From field as DMZ and the To field as LAN1. Set
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the Destination to the IPPBX's DMZ IP address object (DMZ_SIP). Set the Source to
IPPBX_DMZ. Leave the Access field to allow and click OK.
5.6.3 What Can Go Wrong
• The ZyWALL checks the firewall rules in order and applies the first firewall rule the traffic
matches. If traffic matches a rule that comes earlier in the list, it may be unexpectedly blocked.
• The ZyWALL does not apply the firewall rule. The ZyWALL only apply's a zone's rules to the
interfaces that belong to the zone. Make sure the WAN interface is assigned to WAN zone.
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ZyWALL USG100-PLUS User's Guide