D-Link Confidential - D-Link DVX-1000 User Manual

DVX-1000 User Manual
22.2.2.16 ICMP Time Exceeded Messages
The ICMP time exceeded message is generated when the gateway processing the
datagram (or packet, depending on how you look at it) finds the Time To Live
field (this field is in the IP header of all packets) is equal to zero and therefore
must be discarded. The same gateway may also notify the source host via the
time exceeded message.
22.2.2.17 ICMP Ping
ICMP echo request and echo reply messages are allowed, by default.
22.2.2.18 Connections to SOCKS, X-Windows, Open-Windows & NFS ports
The ports to SOCKS, X-Windows, Open-Windows and NFS are blocked, by default,
so as to protect the system from protocol and system administration problems.
22.2.2.19 Telnet/SSH/FTP/HTTP/HTTPS/TFTP Server/Client
The settings related to either of Telnet/SSH/FTP/HTTP/HTTPS/TFTP server/client
can be altered as required.
22.2.2.20 NTP Client
The setting for allowing the packets related to NTP Client can be modified as
required. Currently, these packets are allowed.
22.2.2.21 Packets having source address as target system's external IP address
For natural reasons, such packets are blocked.
22.2.2.22 Packets from machine having private class-A/B/C addresses
Packets from either of the private class A, class B, or class C address received on
the external interface are blocked. Since these address can only be assigned to
LANs.
22.2.2.23 Packets having source IP address as loop back address
Packets claiming to have loop back address as the source IP address are blocked.
22.2.2.24 Malformed broadcast packets
Malformed broadcast packets are blocked. The packets having "0.0.0.0" as the
destination address and/or "255.255.255.255" as the source address are
dropped.
22.2.2.25 Packets having source IP address as multicast IP Addresses
Multicast IP address cannot be put in the source IP address of the packet. Packet
found with such IP address is blocked.
22.2.2.26 Packets having class E addresses
Class E being a reserved class, as yet, the packets having source/destination IP
as Class E address are blocked.

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