ZyXEL Communications ZyWALL 2 Series User Manual

Page of 614
ZyWALL 2 Series User’s Guide 
17-28 
Remote Management Screens 
17.16 Configuring  Security 
To change your ZyWALL’s Security settings, click REMOTE MGNT, then the Security tab. The screen 
appears as shown. 
If an outside user attempts to probe an unsupported port on your ZyWALL, an ICMP response packet is 
automatically returned.  This allows the outside user to know the ZyWALL exists. The ZyWALL series 
support anti-probing, which prevents the ICMP response packet from being sent. This keeps outsiders from 
discovering your ZyWALL when unsupported ports are probed.   
 
Figure 17-24 Security 
The following table describes the fields in this screen. 
Table 17-8 Security 
LABEL DESCRIPTION 
ICMP 
Internet Control Message Protocol is a message control and error-reporting protocol 
between a host server and a gateway to the Internet. ICMP uses Internet Protocol (IP) 
datagrams, but the messages are processed by the TCP/IP software and directly 
apparent to the application user.