Date: Around 1999
have you heard of the ICMP ping command?,can you tell me what it is
about and what does it do?.Thanks
This is a great question, first off I will give some explanation on the
protocols used here.
ICMP is the Internet Control Message Protocol, (ICMP) this is a reporting
protocol used to provide feedback on specific conditions. ICMP messages
are only sent by a router or a destination node in response to a Packet
Internet Gopher (PING) request. PING is used to check the state of a remote
machine via the TCP/IP protocol. For example, you would ping a specific
computer over the internet or intranet and the computer would send back a
ICMP response, these responses are usually 32bits and are usually sent in
sets of 4.
If there is a problem and the computer or router cannot functioning
properly, it will send back a response giving it's current state. If the
router/computer is not up or function properly the ICMP response would send
back a "No Response" or "Request Timed Out" statement to the users letting
them know that the router/computer is not responding.
If the router/computer is up and well, it will send back a response sating
the time it takes for the PING to complete a round trip from the sender to
the host and back to the sender.
This is a nice protocol if used properly. Denial of Service attacks have
been in the news lately, when CNN, Yahoo, and others were crippled by
hackers, they used a fancy version of PING. Denial of service attacks are
brought on by large amounts of PING request and ICMP responses. If one or
many, flooded a given computer/router at one time with PING requests, this
would take up bandwidth and CPU utilization in response to all the PING's it
was receiving. For every PING, it sends a ICMP response, if you send 1
million PING's that computer would have to process 1 million ICMP responses,
thus bringing that computer/router to it's knees.
I hope this helps
Thanks for using NEWTON!!
Joe Noga MCSE, N+
Windows NT/2000 Server Specialist
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Update: June 2012