ZyXEL Communications 2WG - Manual (Page 226)

ZyWALL 2WG Support Notes
All contents copyright (c) 2006 ZyXEL Communications Corporation.
226
computer to be more easily accessed from various locations on the Internet. To use the service, you must
first apply an account from several free Web servers such as WWW.DYNDNS.ORG .
Without DDNS, we always tell the users to use the WAN IP of the ZyWALL to reach our internal server.
It is inconvenient for the users if this IP is dynamic. With DDNS supported by the ZyWALL, you apply a
DNS name (e.g., www.zyxel.com.tw) for your server (e.g., Web server) from a DDNS server. The outside
users can always access the web server using the www.zyxel.com.tw regardless of the WAN IP of the
ZyWALL.
When the ISP assigns the ZyWALL a new IP, the ZyWALL updates this IP to DDNS server so that the
server can update its IP-to-DNS entry. Once the IP-to-DNS table in the DDNS server is updated, the DNS
name for your web server (i.e., www.zyxel.com.tw) is still usable.
A23. When do I need DDNS service?
When you want your internal server to be accessed by using DNS name rather than using the dynamic IP
address we can use the DDNS service. The DDNS server allows to alias a dynamic IP address to a static
hostname. Whenever the ISP assigns you a new IP, the ZyWALL sends this IP to the DDNS server for its
updates.
A24. What DDNS servers does the ZyWALL support?
The DDNS servers the ZyWALL supports currently is WWW.DYNDNS.ORG where you apply the DNS from
and update the WAN IP to.
A25. What is DDNS wildcard?
Some DDNS servers support the wildcard feature which allows the hostname, *.yourhost.dyndns.org, to be
aliased to the same IP address as yourhost.dyndns.org. This feature is useful when there are multiple servers
inside and you want users to be able to use things such as www.yourhost.dyndns.org and still reach your
hostname.
A26. Does the ZyWALL support DDNS wildcard?
Yes, the ZyWALL supports DDNS wildcard that WWW.DynDNS.ORG supports. When using wildcard, you
simply enter yourhost.dyndns.org in the Host field in Network/WAN/DDNS menu.
A27. Can the ZyWALL NAT handle IPSec packets sent by the VPN gateway behind
ZyWALL?
Yes, the ZyWALL's NAT can handle IPSec ESP Tunneling mode. We know when packets go through NAT,
NAT will change the source IP address and source port for the host. To pass IPSec packets, NAT must