af40908294
git-svn-id: svn+ssh://atelier.inf.usi.ch/home/bevilj/group-1@254 a672b425-5310-4d7a-af5c-997e18724b81
99 lines
4.1 KiB
HTML
99 lines
4.1 KiB
HTML
---
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layout: page
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category-page: intermediate
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category-title: Intermediate commands
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author: Joy Albertini
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tags: server ping latency
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title: ping
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previous-page: pages/cmd/interm/passwd.html
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next-page: pages/cmd/interm/ps.html
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---
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The <code>ping</code> command, is used to test connection between a <b>local server/computer</b>
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to a <b>remote UNIX server</b>.<br>
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The ping command sends <b>ICMP Echo Request packets</b> to the remote server for accessing it.
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Each <b>packet echoed back </b> (via an ICMP Echo Response packet) is written to the shell output.
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<pre>
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ping [-flag] server
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</pre>
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The main usages for the <code>ping</code> command are:
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<ol>
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<li>Test whether remote server if working.</li>
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<li>Check the network connectivity from your local machine to a remote one.</li>
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<li>Check for general network issues.</li>
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</ol>
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<pre>
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ping theshell.ch
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</pre>
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The shell will output something like this:
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<i>64 bytes from 98.138.219.232: icmp_seq=0 ttl=49 time=144.781 ms</i> for each packet
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that returns (echoed back).<br>
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To stop the ping command press <code>control + c</code>.
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<h3>Flags</h3>
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<ul>
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<li><b>-c</b>: send limited number of packets with ping -c (nr of packets)<br>
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Example: ping -c 4 yahoo.com, the shell will display the first 4 packets returned,
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and then stop.
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</li>
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<li><b>-n</b>: avoid dns lookup, avoid to lookup symbolic names for host addresses,
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so only numeric output.
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</li>
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<li><b>-a</b>: get an audio warning, when the remote server comes online <br>
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Example: ping -a yahoo.com, server comes online audio signal for every
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packets that returns.
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</li>
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<li><b>-b</b>: Allow pinging a broadcast address (broadcast network, is a network
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with many devices on it).
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</li>
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<li><b>-m</b>: (mark) tag the packets going out.</li>
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<li><b>-f</b>: (Flood ping) For every ECHO_REQUEST sent (.) is printed,
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for every ECHO_REPLY received, a backspace is printed.
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With this command you can easily understand how many packets are being dropped.
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</li>
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<li><b>-i</b>: (interval) set the interval between seending each packet (default 1 second);
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only super-user can set interval values less than 0.2 seconds.
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</li>
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<li><b>-I</b>: (interface-address) set souce adress to a specific interface adress,
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example the name of the device or IP. When pinging local adresses IPV6, is a needed flag.
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</li>
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<li><b>-l</b>: (preload) ping send packets but don't wait for reply.
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Admin permissions are required to use this flag.
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</li>
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<li><b>-L</b>: Remove loopback of multicast packets.</li>
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<li><b>-N</b>: (Nioption) send ICMpv6 request, instead of Echo requests
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<ul>
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<li><b>ipv6</b>: request Ipv6 adresses.</li>
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<li><b>ipv4-all</b>: request Ipv4 adresses.</li>
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</ul>
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</li>
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<li><b>-p</b>: (pattern) specify up to 16 number to fill out the packets sent.</li>
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<li><b>-D</b>: print timestamp (unix time + microseconds) in each line.</li>
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<li><b>-q</b>: (Quiet output) Nothing displayed except the summary lines at the start
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and at the end.
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</li>
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<li><b>-R</b>: (Record route), displays the route buffer on the packets that include
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RECORD_ROUTE in the ECHO_REQUEST.
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</li>
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<li><b>-r</b>: bypass the normal routing in a directly-attached network.</li>
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<li><b>-s</b>: (packetsize) Specifies the data bytes to send (default is 56 that
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+ 8 byte of ICMP = 64 ICMP data bytes).
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</li>
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<li><b>-t</b>: set IP time-to-live (set how long execute ping in seconds).</li>
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<li><b>-U</b>: print full user-to-user latency (legacy ping behaviour).</li>
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<li><b>-v</b>: output verbose on output</li>
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<li><b>-V</b>: Display verion of command</li>
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<li><b>-w</b>: (deadline) Timeout in seconds of ping command, regardless of how\
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many packets have been sent.
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</li>
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<li><b>-W</b>: (timeout), time waiting for a response from the server, if the server
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dosen't reply in the time set, the ping command will stop.
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</li>
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</ul>
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