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Topic: ICMP Echo Request

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	Why Ping is not Good for Network Measurements (Site not responding. Last check: 2007-10-11)
		ICMP messages indicate, for example, that a packet should take another path (ICMP Redirect) or that a service is not available or that IP fragmentation would be necessary (ICMP Destination Unreachable).
		Echo Request and Echo Reply packets that exceed those limits are simply and silently discarded.
		ICMP echo packets are often given second-class treatment by routers and target hosts.
	www.iwl.com /Resources/Papers/icmp-echo_print.html (1245 words)

	Netmask-based ICMP Echo Request Smurf Broadcast Scanning with Crafted ICMP Payloads using SendIP
		The first 8 bits of the ICMP echo and echo reply message is the type field, which defines the format of the remaining message.
		The rationale behind this is that the echo reply packet must return the payload data sent in the echo request packet, and therefore the attacker will know which broadcast address corresponds to the responding machine.
		For instance, when crafting an ICMP echo request packet, if a value for the IP ID is not passed as an argument on the command line, the default value is set using a random value.
	www.whitehats.ca /main/members/Jeff/gcia_assign_2/gcia_assign_2.html (3250 words)

	ICMP Echo Request - Wikipedia, the free encyclopedia
		The Echo Request is an ICMP message which sends a packet of data to the host and expects that data to be sent in return in an Echo Reply.
		The host must respond to all Echo Requests with an Echo Reply containing the exact data received in the request message.
		The data received by the Echo Request must be entirely included in the Echo Reply.
	en.wikipedia.org /wiki/ICMP_Echo_Request (150 words)

	SANS Institute - Intrusion Detection FAQ: How can attacker use ICMP for reconnaissance?
		ICMP error messages are never sent in response to a datagram that is destined to a broadcast or a multicast address.
		ICMP error messages are never sent in response to a datagram whose source address does not represents a unique host (the source address cannot be zero, a loopback address, a broadcast address or a multicast address).
		ICMP Error Messages may help to determine the kind ACL of the filtering device is being used and allow one to choose the tactics accordingly.
	www.sans.org /resources/idfaq/icmp_misuse.php (3912 words)

	Identifying ICMP Hackery Tools Used In The Wild Today
		The sending side initializes the identifier (used to identify Echo requests aimed at different destination hosts) and sequence number (if multiple Echo Requests are sent to the same destination host), adds some data (arbitrary) to the data field and sends the ICMP Echo to the destination host.
		The second pair of ICMP Echo request and reply is identical to the first pair, except for the IP Identification number (which is used from the underlying operating system).
		The checksum for the ICMP header is the same with both of the pairs, since the ICMP sequence numbers and the ICMP identification numbers used are the same.
	www.securityfocus.com /infocus/1183 (2407 words)

	ICMP type 8, Echo request message
		The data received in the echo request message must be returned in the echo reply message.
		The identifier and sequence number may be used by the echo sender to aid in matching the replies with the echo requests.
		A router MUST be prepared to receive, reassemble and echo an ICMP Echo Request datagram at least as the maximum of 576 and the MTUs of all the connected networks.
	www.networksorcery.com /enp/protocol/icmp/msg8.htm (548 words)

	"smurf" IP Denial-of-Service Attacks
		Description The two main components to the smurf denial-of-service attack are the use of forged ICMP echo request packets and the direction of packets to IP broadcast addresses.
		ICMP echo reply traffic (the traffic from the intermediary) could be blocked at the victim's router; however, that will not necessarily prevent congestion that occurs between the victim's router and the victim's Internet service provider.
		Problem Description A solution at the intermediate network being abused to generate the ICMP echo replies is to either block ICMP echo requests directed to a broadcast address or to configure the hosts on that network not to respond to such an ICMP request.
	www.ciac.org /ciac/bulletins/i-021a.shtml (3147 words)

	icmp
		ICMP is mainly designed for a host/router to report the error status of an IP packet.
		ICMP is created in response to a specific IP datagram or an ICMP request.
		For error report, ICMP includes the header of the datagram and and the first 64 bits of the data portion (of the target datagram).
	www.csusm.edu /hylin/cs537s00/icmp.html (508 words)

	ICMP Attacks
		ICMP is used by the IP layer to send one-way informational messages to a host.
		The ICMP "Redirect" message is commonly used by gateways when a host has mistakenly assumed the destination is not on the local network.
		Since the received ICMP echo request packet is larger than the normal IP packet size, it's fragmented.
	www.networkdictionary.com /security/ICMPAttacks.php (362 words)

	SANS Institute - Intrusion Detection FAQ: I am seeing odd ICMP traffic, what could this mean?
		Sites that see outgoing ICMP broadcast packets with the source IP address not part of their own internal address space may well be launching a smurf attack.
		ICMP in particular "ping" traffic was once considered to be benign.
		There are a variety of problems that have been noted with respect to echo requests and replies, they include smurf, network mapping and loki or an inverse mapping technique.
	www.sans.org /resources/idfaq/traffic.php (931 words)

	[No title]
		ECHO request datagrams (``pings'') have an IP and ICMP header, followed by a struct timeval, and then an arbi- trary number of ``pad'' bytes used to fill out the packet.
		Default datagram length is 64 bytes (8 ICMP header bytes + 56 data bytes), but this may be changed using the command line option length.
		If an optional length is specified, it is used as the length of the data portion of the ICMP ECHO request packet.
	www-iepm.slac.stanford.edu /pinger/nikhef/ping.txt (1534 words)

	ICMP Echo DoS
		An ICMP echo request packet would be edited so that the destination address was the first system, the source address was the second target system.
		Source and destination ports within the packet would both be the ICMP echo port number (7 from memory).
		The only difference between the request and reply (apart from checksums and the reversal of source and destination addresses) is this ICMP 'Packet Type' flag.
	attrition.org /security/denial/w/icmp-dos.dos.html (1211 words)

	Chapter 5 - Part III: Internet Core Protocols \| Page 1 \| June 12, 2000 (Site not responding. Last check: 2007-10-11)
		ICMP Echo Request query messages for the seed data, instead of UDP datagrams.
		Another advantage to using ICMP Echo Request messages is that these messages contain built-in Identifier and Sequence Number fields, which provide better packet-tracking mechanisms for traceroute to use in its per-hop calculations than UDP port numbers do.
		Once the seed ICMP Echo Request query messages have reached the destination system, they should be responded to with ICMP Echo Reply query messages, indicating that the complete path has been discovered.
	www.networkcomputing.com /netdesign/1111icmp1.html (1496 words)

	System and method for dynamically refining PMTU estimates in a multimedia datastream internet system - Patent 5892753
		Assuming that eventually, by the repeated process of downsizing the size of the echo request packets, the transmission is completed from the local system 10 through the Internet 12 to the target system 14, an ICMP echo response packet 22 will be generated by the target system 14 acknowledging this packet.
		Because the ICMP probes are utilized instead of actual payload data, the PMTU discovery process may be initiated as soon as the connection information is obtained without having to wait for applications to actually transmit data.
		If the request makes it all the way to the target and the response therefrom is received successfully by the host, then the PMTU for that connection may be said to have been discovered.
	www.freepatentsonline.com /5892753.html (5241 words)

	Protecting Against Denial of Service Attacks (Site not responding. Last check: 2007-10-11)
		When the ICMP echo request reaches the intermediary network, it is converted to a Layer 2 broadcast and sent to the hosts on the intermediary network.
		For each ICMP echo request packet sent by the attacker, a number of ICMP replies equal to the number of hosts on the intermediary network are sent to the victim.
		When the ICMP echo request packet arrives at the target subnet, it is converted to a Layer 2 broadcast and sent to the connected hosts.
	www.foundrynet.com /services/documentation/xmr_user/DoS_Protection.html (1680 words)

	ICMP (Internet Control Message Protocol) (Linktionary term)
		ICMP is an error-reporting protocol that works in concert with IP.
		The router puts an ICMP message in an IP datagram and sends it back to the source of the datagram that could not be delivered.
		There are five ICMP error messages that may be returned to a sender in response to problems on the network or with datagrams.
	www.linktionary.com /i/icmp.html (378 words)

	Secrets of Network Cartography - ICMP Echo Request Ping (-PE)
		This is the same type of ICMP echo request that is sent in the default ICMP echo request and TCP ACK ping combination.
		If a response is not received to the ICMP echo request, the IP address is not active or the connection to the remote device is filtered.
		It's very common for ICMP to be filtered through firewalls or packet filters, so a response to an ICMP echo request would be indicative of a link that has very little (if any) filtering.
	www.networkuptime.com /nmap/page4-3.shtml (452 words)

	ICMPPingRewriter - Click documentation
		Rewrites ICMP echo requests and replies by changing their source and/or destination addresses.
		Replies to the rewritten request are themselves rewritten; the rewritten replies look like they were responding to the original request.
		On the first input, echo requests with no corresponding mapping cause new mappings to be created, while echo replies with no corresponding mapping are passed along unchanged.
	pdos.csail.mit.edu /click/doc/ICMPPingRewriter.n.html (261 words)

	Chapter 7. Ping Program
		When the ICMP echo reply is returned, the sequence number is printed, followed by the TTL, and the round-trip time is calculated.
		Either the echo requests or the echo replies for sequence numbers 1, 2, 3, 4, 6, 10, II, 12, and 13 were lost somewhere.
		When the datagram reaches the final destination, the list of IP addresses should be copied into the outgoing ICMP echo reply, and all the routers on the return path also add their IP addresses to the list.
	members.tripod.com /~azeemk/Stevens/pingprog.htm (3999 words)

	Ping Tunnel - Send TCP traffic over ICMP
		In theory, it is possible to have the proxy also use echo request packets (and thus make it operate without root), but these packets are not necessarily forwarded to the client beyond the host network, so they are not used.
		The ICMP sequence number field is not used by ptunnel, mostly due to fears that some routers might drop packets whose sequence number repeats.
		This happens when the ICMP packet is an echo request (which the OS handles by itself) or when the ICMP packet is a resend (for some weird reason).
	www.cs.uit.no /~daniels/PingTunnel (2591 words)

	ICMP - Webled.com (Site not responding. Last check: 2007-10-11)
		[ The operation of ICMP is illustrated in the frame transition diagram ]...
		[ the ICMP ECHO request and the IP protocol type is set to "ICMP" to ]...
		ICMP endeavors to secure the co-operation of ]...
	www.webled.com /ICMP.htm (435 words)

	ICMP Echo Reply - Wikipedia, the free encyclopedia
		The Echo Reply is an ICMP message generated in response to an ICMP Echo Request message, and is mandatory for all hosts and routers.
		Type and Code must be set to 0.
		The Identifier and Sequence Number can be used by the client to manage which Echo Requests are associated with the Echo Replies.
	en.wikipedia.org /wiki/ICMP_Echo_Reply (132 words)

	ICMP type 0, Echo reply message
		This message is generated in response to an ICMP type 8 (Echo request) message.
		Can be used to help match echo requests to the associated reply.
		Used to help match echo requests to the associated reply.
	www.networksorcery.com /enp/protocol/icmp/msg0.htm (443 words)

	ICMPTX (IP-over-ICMP) HOWTO
		There is a similar, thoroughly undocument program called itun, a simple icmp tunnel that claims to do the same thing.
		Bryan Ford is for the proxy to not only wrap the IP packet in the ICMP packet, but to include an additional header that contains the number of additional ICMP packets required to complete the current IP packet; call this number N.
		The proxy uses the N ICMP reply packets to transmit the remaining fragments of the IP packet.
	thomer.com /icmptx (1004 words)

	FireWall-1 FAQ: HIDE NAT and Traceroute on Windows (Site not responding. Last check: 2007-10-11)
		With ICMP packets, there is no source or destination ports, so it has to use the data portion of an ICMP packet to encode state information (it's usually garbage anyway).
		An ICMP Echo-Reply packet usually sends back all the data that was sent to it, so a normal ICMP Echo-Request and ICMP Echo-Reply sequence should work fine through a HIDE NAT.
		However, the ICMP Time-Exceeded packets usually sent back by each hop do not contain the entire data portion of the packet, and it's usually not enough information for FireWall-1 to decode which machine sent the original ICMP Echo Request.
	www.txwesleyan.edu /~jvortega/security/fw-1/0113.html (373 words)

	ICMP Echo Request Resent With Different Length
		The incoming ECHO REPLY are associated with a specific ECHO REQUEST through the use of an identifier common to both.
		Data may be contained in the ECHO REQUEST message which must be retransmitted, exactly, in the associated ECHO REPLY message.
		The existence of such a packet could be caused by an error, but also could indicate that the ICMP protocol is being used to tunneling other network traffic in an attempt to evade detection or access control.
	www.juniper.net /security/auto/vulnerabilities/vuln2784.html (190 words)

	Echo Reply
		ICMP ECHO-REPLY packets are the responses sent back from the host that is being PING'ed.
		ICMP ECHO-REPLY messages are actually encapsulated within an IP datagram even though the standards document for IP states that IP itself must provide the ICMP functionality.
		Always remember that the ICMP ECHO-REPLY is a different datagram from the ICMP ECHO request and it takes additional clock ticks to copy the ECHO request information, destroy the original ECHO request, create a new ECHO-REPLY, encapsulate it within IP, CRC check the IP headers and then transmit the reply.
	www.inetdaemon.com /tutorials/internet/icmp/echo_reply.shtml (186 words)

	ICMP Type Numbers (from RFC 1700)
		The purpose of these control messages [ICMP] is to provide feedback about problems in the communication environment, not to make IP reliable.
		Also ICMP messages are only sent about errors in handling fragment zero of fragemented datagrams.
		Many of the types of ICMP message are now obsolete and are no longer seen in the Internet.
	www.erg.abdn.ac.uk /users/gorry/course/inet-pages/icmp-code.html (254 words)

	Sys-Security.com - Because Security is not Trivial
		It is the home of the "ICMP Usage In Scanning" research project.
		Identifying ICMP Hackery Tools Used In The Wild Today, December 4, 2000.
		Ping uses the value of 64 as its default value for the IP TTL field with ICMP Echo requests.
	www.sys-security.com /archive/securityfocus/icmptools.html (2384 words)

	Linux : Iptables # 9 Allow ICMP ping \| nixCraft
		ICMP echo-request type will be block by above rule.
		An ICMP ping is an “icmp echo request” that is followed up by an “icmp echo reply”.
		There are a icmp packets you dont want to recieve or reply to.
	www.cyberciti.biz /tips/linux-iptables-9-allow-icmp-ping.html (776 words)

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