ZyXEL Communications P-660HWP-D1, User Manual

Page: 177 / 374

Chapter 11 Firewall Configuration
P-660HWP-D1 User’s Guide
177
11.9 Anti-Probing
If an outside user attempts to probe an unsupported port on your P-660HWP-D1, an ICMP
response packet is automatically returned. This allows the outside user to know the P-
660HWP-D1 exists. The P-660HWP-D1 supports anti-probing, which prevents the ICMP
response packet from being sent. This keeps outsiders from discovering your P-660HWP-D1
when unsupported ports are probed.
Internet Control Message Protocol (ICMP) 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.
Refer to
Section 10.1 on page 149 for more information.
Click Security > Firewall > Anti Probing to display the screen as shown.
Figure 101 Firewall: Anti Probing
SSH(TCP/UDP:22) Secure Shell Remote Login Program.
STRMWORKS(UDP:1558) Stream Works Protocol.
SYSLOG(UDP:514) Syslog allows you to send system logs to a UNIX server.
TACACS(UDP:49) Login Host Protocol used for (Terminal Access Controller Access
Control System).
TELNET(TCP:23) Telnet is the login and terminal emulation protocol common on the
Internet and in UNIX environments. It operates over TCP/IP networks.
Its primary function is to allow users to log into remote host systems.
TFTP(UDP:69) Trivial File Transfer Protocol is an Internet file transfer protocol similar
to FTP, but uses the UDP (User Datagram Protocol) rather than TCP
(Transmission Control Protocol).
VDOLIVE(TCP:7000) Another videoconferencing solution.
Table 64 Predefined Services (continued)
SERVICE DESCRIPTION