Ping 0.1.4

Table of Contents

1. What is ping ?
2. How to use ping
3. How does it compares with Microsoft's ping and tracert
4. Compiling ping
   1. On Windows from the command Line
   2. On Windows from Visual Studio
   3. On Linux using Wine
5. Possible enhancements
6. Reporting bugs or enhancement

1. What is ping ?

The purpose of this Ping implementation initially was to demonstrate the use of the Windows ICMP library. While it's still a good example in this regard it is also worth it in itself as a powerful ping utility. It's behavior was closely modeled after that of Linux with some extensions taken from traceroute.

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, followed by a ``struct timeval'' and then an arbitrary number of ``pad'' bytes used to fill out the packet.

In trace mode Ping will print the route packets take to reach the specified network host. The Internet is a large and complex aggregation of network hardware connected together by gateways. Tracking the route one's packets follow (or finding the miscreant gateway that's discading your packets) can be difficult. In trace mode Ping uses the IP protocol ``time to live'' field and attempts to elicit an ICMP_ TIME_EXCEEDED response from each gateway along the path to some host.

2. How to use ping

Ping is quite versatile so there is not a single way to use it. Though here are some of its uses:

• Checking that a host is reachable or alive.
  Right after you have installed a new host on the network the first thing to try is to ping another host on the network. Once you can ping other hosts you should try to ping the newly installed host from somewhere on the network. Ping is one of the most important diagnosis tool when trying to discover network configuration problems as if ping does not work you should not expect anything else to go through.
  Ping can also be used to check whether a host is still up. For exemple you might find that some file server is dead slow. Dead ??? Check it with ping.
  For this kind of use all you have to do is:
  
  ping remote.host
  
  
• Finding out the path to a host.
  For this task you might use "tracert.exe". Ping can provide a replacement for this tool, just run:
  
  ping -t target.host
  
  
• But ping can also give you more information on the RTT for each host of the path. For this run something like:
  
  ping -t -c 10 -q target.host
  
  This command will give you the following statistics for each host:
  • number of sent/received packets for this host
  • loss percentage
  • minimum/average/maximum rtt as measured from these packets
  If you don't specify '-q' you will get each RTT (but not the stats).
• Keeping a temporary connexion up.
  If you have a connection which is kept up only as long as there is traffic on it ping may be a solution for keeping it up. Of course this is probably something you should be careful about, after all temporary connections are meant to be... temporary. Usually to keep the connection up all you have to do is have ping run and send a packet every 2 or 5 minutes. The following command will do just that:
  
  ping -i 300 remote.host
  
  You should also have a look at the provided man page, "ping.txt". It describes the ping options in more detail than here and also adds some more information about the problems you will find when using the traceroute mode.

3. How does it compares with Microsoft's ping and tracert

Microsoft's tools implement the source routing an record route options.

With Microsoft's ping you cannot specify the interval between two packets. Also this ping conforms to the Unices ping options so you may feel more comfortable with it.

Microsoft's tracert just sends 3 probes per host. You cannot configure it for more or get more interesting statistics. Also you cannot specify the maximum RTT to use.

Finally both Microsoft tools give you a RTT rounded down to a millisecond. Even worse the RTT can be underevaluated by up to 2 milliseconds. This ping tool can give you, most of the time, a RTT which is accurate to about 10 microseconds.

Everything that ping does not give you, you can implement it. Of course Microsoft's tools don't come with the source :-).

4. Compiling ping

To compile ping you must also get the icmp package. It should be available from the same place as ping i.e. currently only http://fgouget.free.fr/bing/

You will also need Visual C++ 2.0 or higher. Note that with some modifications in the makefile you should be able to compile it with another compiler.

4.1. On Windows from the command Line

Go in the ping directory and just type:

    nmake -f makefile.win

If the compiler does not find the "ipexport.h" header then specify where you have the icmp headers like in the command below:

    name ICMP_DIR=../icmp_dev-0.1.2 -f makefile.win

There are options you may add to this command line to customize the result. All options are disabled by default:

• DLL=1
  Links ping with the Dll C library rather. This makes ping much smaller but may require that you ship the Dll with it.
• DEBUG=1
  Builds a debug version.
• BROWSER=1
  Generates Visual C++'s "browser" database.

and commands

• all or <nothing>
  Builds ping.
• clean
  Removes the generated files.
• help
  Describes the makefile options.

4.2. On Windows from Visual Studio

Open the 'ping.dsw' file and compile. This is a Visual Studio 6 Workspace file but it should work in Visual Studio 5 too.

4.3. On Linux using Wine

Go to the directory where ping is and run the following commands:

• autoconf
• ./configure
• make

When running the configure script you may need to specify where Wine is if it is installed in a non standard location (in your home directory for instance). Do so as follows:

./configure --with-wine=$HOME/wine

Run "./configure help" for more information on configure's other options. The makefile supports the following commands:

• all or <nothing>
  Builds ping.
• clean
  Removes the generated files.

5. Possible enhancements

• It should be possible to implement more of the IP header options:
  • record route
  • source routing
  • type of service
  • don't fragment flag
• The median RTT would probably be more interesting than the mean RTT.

6. Reporting bugs or enhancements

If you want to report a bug or make an enhancement suggestion or want your modifications to be integrated to this package, send a mail to: fgouget@free.fr

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