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DSL-514 ADSL Router User's Guide
Firewall
Firewall Rules is an advance feature used to deny or allow traffic from passing through the DSL-514. It
works in the same way as IP Filters with additional settings. You can create more detailed rules for the
Router.
DoS Protection: Use the following denial of service protection: (1)SYN DoS (2)ICMP DoS (3)Per-host
DoS protection
SYN Flooding checking: is a well-known Denial Of Service attack on TCP based services. TCP needs a
3-way handshake before the actual communication starts between two hosts. Whenever a new
connection request comes in, the server allocates some resources for serving it. A malicious intruder can
forge a huge amount of service requests over a very short period, and make your server run out of its
resources. When you enable SYN flooding control, filters out such forged service requests while allowing
legitimate requests to pass through.
ICMP Redirection checking: is a standard ICMP message, which conveys the better route information
to the source. After receiving this message, the recipient updates its routing table with the routing
information present in the message. As there is no strong authentication mechanism built into this
process, an intruder can make a target update its routing table with the information of his/her interest. By
this way an intruder can potentially get access to the data originated from the target host.
Source Routing checking: With strict and loose source routing, as specified in IP standard RFC 791,
one can make data grams take a predefined path towards a destination. By this way, an intruder can gain
more information about the corporate network, which he or she can then misuse.
Winnuke Attack checking: Apparently Windows doesn't know how to handle OOB, so it panics and
crazy things happen. Windows also sometimes has trouble handling anything on a network at all after an
attack like this. A reboot fixes whatever damage this causes.
Hacker Log SysLog: Specifies how attempted violations of the firewall settings will be tracked. Records
of such events can be sent via Ethernet to be handled by a system utility Ethernet to (trace) or can
e-mailed to specified administrators.
E-mail Address: Specifies the e-mail addresses of the administrators who should receive notices of any
violations.
attempted firewall
Service Filtering: With this table you can define the transport protocol and used port for the services.
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