ZyXEL P-662H-67 User Guide - Page 185
Anti-Probing
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Chapter 11 Firewall Configuration Table 68 Predefined Services (continued) SERVICE DESCRIPTION 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. 11.9 Anti-Probing If an outside user attempts to probe an unsupported port on your ZyXEL Device, an ICMP response packet is automatically returned. This allows the outside user to know the ZyXEL Device exists. The ZyXEL Device supports anti-probing, which prevents the ICMP response packet from being sent. This keeps outsiders from discovering your ZyXEL Device 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 157 for more information. Click Security > Firewall > Anti Probing to display the screen as shown. Figure 106 Firewall: Anti Probing P-662H/HW-D Series User's Guide 185