G.shdsl Router User Manual
Level 5: Application
Level 4: TCP
Level 3: IP
Level 2: Data Link
Level 1: Physical
Telnet
FTP
Http
SMTP
Host PC
Proxy Server
Public Server
Request Page
Check URL
Request Page
Return Page
Return Page
Filter Content
External
Interface
Internal
Interface
Proxy Application
Denial of Service Attack
Denial of service (DoS) attacks typically come in two
flavors: resource starvation and resource overload. DoS
attacks can occur when there is a legitimate demand for
a resource that is greater than the supply (i.e. too many
web requests to an already overloaded web server).
Software vulnerabilities or system misconfigurations can also cause DoS situations. The
difference between a malicious denial of service and simple system overload is the requirement of
an individual with malicious intent (attacker) using or attempting to use resources specifically to
deny those resources to other users.
Inturruption
Ping of death-
On the Internet, ping of death is a kind of denial of service (DoS) attack caused by
an attacker deliberately sending an IP packet larger than the 65,536 bytes allowed by the IP
protocol. One of the features of TCP/IP is fragmentation; it allows a single IP packet to be broken
down into smaller segments. Attackers began to take advantage of that feature when they found
that a packet broken down into fragments could add up to more than the allowed 65,536 bytes.
Many operating systems didn't know what to do when they received an oversized packet, so they
froze, crashed, or rebooted. Other known variants of the ping of death include teardrop, bonk and
nestea.
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