ZyXEL Communications P-2602HWLNI, Руководство пользователя, Страница: 354 / 496

Chapter 23 Remote Management Configuration
P-2602HWLNI User’s Guide
354
Figure 202 Remote Management: ICMP
The following table describes the labels in this screen.
23.10 SSH
You can use SSH (Secure SHell) to securely access the ZyXEL Device’s command line
interface. Specify which interfaces allow SSH access and from which IP address the access
can come.
Unlike Telnet or FTP, which transmit data in plaintext (clear or unencrypted text), SSH is a
secure communication protocol that combines authentication and data encryption to provide
secure encrypted communication between two hosts over an unsecured network. In the
following figure, computer
A on the Internet uses SSH to securely connect to the WAN port of
the ZyXEL Device for a management session.
Table 144 Remote Management: ICMP
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.
Respond to Ping
on
The ZyXEL Device will not respond to any incoming Ping requests when Disable is
selected. Select LAN to reply to incoming LAN Ping requests. Select WAN to reply
to incoming WAN Ping requests. Otherwise select LAN & WAN to reply to both
incoming LAN and WAN Ping requests.
Do not respond to
requests for
unauthorized
services
Select this option to prevent hackers from finding the ZyXEL Device by probing for
unused ports. If you select this option, the ZyXEL Device will not respond to port
request(s) for unused ports, thus leaving the unused ports and the ZyXEL Device
unseen. By default this option is not selected and the ZyXEL Device will reply with
an ICMP Port Unreachable packet for a port probe on its unused UDP ports, and a
TCP Reset packet for a port probe on its unused TCP ports.
Note that the probing packets must first traverse the ZyXEL Device's firewall
mechanism before reaching this anti-probing mechanism. Therefore if the firewall
mechanism blocks a probing packet, the ZyXEL Device reacts based on the
corresponding firewall policy to send a TCP reset packet for a blocked TCP packet
or an ICMP port-unreachable packet for a blocked UDP packets or just drop the
packets without sending a response packet.
Apply Click Apply to save your customized settings and exit this screen.
Cancel Click Cancel to begin configuring this screen afresh.