Re: Ping, ICMP and TCP Ping

From: jlmb (jlmb_at_cableonda.net)
Date: 08/28/05

  • Next message: Nikolai Alexandrov: "Re: Ping, ICMP and TCP Ping" 
    Date: Sat, 27 Aug 2005 19:33:49 -0500

    zaka rias wrote:
    > hi,
    >
    > Im learning protocol tcp/ip and icmp, and as far as i
    > know that Ping (software) is using ICMP protocol to
    > transmit packets and PING is identic with ICMP.
    >

    Not sure what you meant but this should clear you it up a bit:

    DESCRIPTION
           ping uses the ICMP protocol's mandatory ECHO_REQUEST datagram to
    elicit an ICMP ECHO_RESPONSE from a host or gateway. ECHO_REQUEST
    datagrams (``pings'') have an IP and ICMP header

    This comes from a linux ping(8) man page.

    > I have always wrapped my thinking that ICMP (and Ping
    > Program) echo/reply was a port 0 thing (like someone
    > said in
    > http://forum.sans.org/discus/messages/78/10869.html?1110164175
    > ), and that's wrong.

    Well, I believe the post By T. Brian Granier (bgranier) is correct. It's
    not about ports, it's about codes and types.

    ftp://ftp.rfc-editor.org/in-notes/rfc792.txt

    > i just wonder if this kind of method called TCP-PING,
    > when actually TCP-PING isnt using ICMP protocol, and
    > once more -> TCP PING 's using port when actually
    > PING program is not using a port to communicate.

    ping(8) does not uses a port to communicate because it's based on ICMP.
    TCP-PING method on the other hand works by sending a TCP ack packet to a
    specified port, no it DOESN'T use ICMP. I believe this METHOD is called
    TCP-PING because it can be used to perform a similar function as ICMP
    ping, to determine if a machine is up.

    man nmap(1) and read the Ping scanning description, be sure to read the
    ACK scan too.

    luck

  • Next message: Nikolai Alexandrov: "Re: Ping, ICMP and TCP Ping"

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