path: root/ru_RU.KOI8-R/articles/ipsec-must/article.xml

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<!DOCTYPE article PUBLIC "-//FreeBSD//DTD DocBook XML V5.0-Based Extension//EN"
	"../../../share/xml/freebsd50.dtd">
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     Original revision: r25543
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<article xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink" version="5.0" xml:lang="ru">
  <info><title>îÅÚÁ×ÉÓÉÍÏÅ ÉÓÓÌÅÄÏ×ÁÎÉÅ ÒÁÂÏÔÙ IPsec ×Ï FreeBSD</title>
    

    <author><personname><firstname>David</firstname><surname>Honig</surname></personname><affiliation>
	<address><email>honig@sprynet.com</email></address>
      </affiliation></author>

    <pubdate>1999-05-03</pubdate>

    <legalnotice xml:id="trademarks" role="trademarks">
      &tm-attrib.freebsd;
      &tm-attrib.opengroup;
      &tm-attrib.general;
    </legalnotice>

    <releaseinfo>$FreeBSD$</releaseinfo>

    <abstract>
      <para>÷Ù ÔÏÌØËÏ ÞÔÏ ÕÓÔÁÎÏ×ÉÌÉ É ÎÁÓÔÒÏÉÌÉ IPsec, É ÏÎÏ,
	ËÁÖÅÔÓÑ, ÚÁÒÁÂÏÔÁÌÏ.  ëÁË ÜÔÏ ÍÏÖÎÏ ÐÒÏ×ÅÒÉÔØ?  ñ ÏÐÉÛÕ ÍÅÔÏÄ
	ÜËÓÐÅÒÉÍÅÎÔÁÌØÎÏÊ ÐÒÏ×ÅÒËÉ ÐÒÁ×ÉÌØÎÏÇÏ ÆÕÎËÃÉÏÎÉÒÏ×ÁÎÉÑ
	IPsec.</para>
    </abstract>
  </info>

  <sect1 xml:id="problem">
    <title>ðÏÓÔÁÎÏ×ËÁ ÚÁÄÁÞÉ</title>

    <para>äÌÑ ÎÁÞÁÌÁ ÐÒÅÄÐÏÌÏÖÉÍ, ÞÔÏ ÷Ù <link linkend="ipsec-install">
      ÎÁÓÔÒÏÉÌÉ <emphasis>IPsec</emphasis></link>.  ëÁË ÷Ù
      ÕÚÎÁÅÔÅ, ÞÔÏ IPsec <link linkend="caveat">ÒÁÂÏÔÁÅÔ</link>?
      îÅÓÏÍÎÅÎÎÏ, ÓÏÅÄÉÎÅÎÉÑ ÎÅ ÂÕÄÅÔ, ÅÓÌÉ ÷Ù ÎÅ×ÅÒÎÏ ÅÇÏ
      ÓËÏÎÆÉÇÕÒÉÒÏ×ÁÌÉ.  é ÏÎÏ, ËÏÎÅÞÎÏ, ÐÏÑ×ÉÔÓÑ × ×Ù×ÏÄÅ ËÏÍÁÎÄÙ
      &man.netstat.1;, ËÏÇÄÁ ÷Ù ×Ó£ ÓÄÅÌÁÅÔÅ ×ÅÒÎÏ.  îÏ ÍÏÖÎÏ ÌÉ
      ËÁË-ÔÏ ÐÏÄÔ×ÅÒÄÉÔØ ÓÁÍ ÆÁËÔ ÆÕÎËÃÉÏÎÉÒÏ×ÁÎÉÑ IPsec?</para>
  </sect1>

  <sect1 xml:id="solution">
    <title>òÅÛÅÎÉÅ</title>

    <para>äÌÑ ÎÁÞÁÌÁ ÎÅÍÎÏÖËÏ ËÒÉÐÔÏÇÒÁÆÉÞÅÓËÏÊ ÔÅÏÒÉÉ:</para>

    <orderedlist>
      <listitem>
	<para>ûÉÆÒÏ×ÁÎÎÙÅ ÄÁÎÎÙÅ ÒÁ×ÎÏÍÅÒÎÏ ÒÁÓÐÒÅÄÅÌÅÎÙ ÐÏ ÏÂÌÁÓÔÉ
	  ÏÐÒÅÄÅÌÅÎÉÑ, ÔÏ ÅÓÔØ ËÁÖÄÙÊ ÓÉÍ×ÏÌ ÉÍÅÅÔ ÍÁËÓÉÍÁÌØÎÕÀ
	  ÜÎÔÒÏÐÉÀ;</para>
      </listitem>

      <listitem>
	<para><quote>óÙÒÙÅ</quote> É ÎÅÓÖÁÔÙÅ ÄÁÎÎÙÅ ËÁË ÐÒÁ×ÉÌÏ
	  ÉÚÂÙÔÏÞÎÙ, ÔÏ ÅÓÔØ ÉÈ ÜÎÔÒÏÐÉÑ ÍÅÎØÛÅ ÍÁËÓÉÍÁÌØÎÏ
	  ×ÏÚÍÏÖÎÏÊ.</para>
      </listitem>
    </orderedlist>

    <para>ðÒÅÄÐÏÌÏÖÉÍ, ÞÔÏ Õ ÷ÁÓ ÉÍÅÅÔÓÑ ×ÏÚÍÏÖÎÏÓÔØ ÉÚÍÅÒÉÔØ ÜÎÔÒÏÐÉÀ
      ×ÈÏÄÑÝÅÇÏ É ÉÓÈÏÄÑÝÅÇÏ ÔÒÁÆÉËÁ ÎÁ ÓÅÔÅ×ÏÍ ÉÎÔÅÒÆÅÊÓÅ.  ÷ ÜÔÏÍ
      ÓÌÕÞÁÅ ÷Ù ÓÍÏÖÅÔÅ ÌÅÇËÏ ÏÔÌÉÞÉÔØ ÚÁÛÉÆÒÏ×ÁÎÎÙÅ ÄÁÎÎÙÅ ÏÔ
      ÏÔËÒÙÔÙÈ, ÐÒÉÞ£Í ÄÁÖÅ × ÔÏÍ ÓÌÕÞÁÅ, ËÏÇÄÁ ÞÁÓÔØ ÄÁÎÎÙÈ ×
      <quote>ÒÅÖÉÍÅ ÛÉÆÒÏ×ÁÎÉÑ</quote> ÐÅÒÅÄÁ£ÔÓÑ × ÏÔËÒÙÔÏÍ ×ÉÄÅ, Ë
      ÐÒÉÍÅÒÕ ×ÎÅÛÎÉÅ ÚÁÇÏÌÏ×ËÉ IP, ËÏÔÏÒÙÅ ÉÓÐÏÌØÚÕÀÔÓÑ ÄÌÑ
      ÍÁÒÛÒÕÔÉÚÁÃÉÉ.</para>

    <sect2 xml:id="MUST">
      <title>MUST</title>

      <para><quote>õÎÉ×ÅÒÓÁÌØÎÙÊ óÔÁÔÉÓÔÉÞÅÓËÉÊ ôÅÓÔ ÄÌÑ çÅÎÅÒÁÔÏÒÏ×
	óÌÕÞÁÊÎÙÈ þÉÓÅÌ</quote> õÜÌÉ íÁÕÒÅÒÁ (Ueli Maurer's Universal
	Statistical Test for Random Bit Generators), ÓÏËÒÁÝ£ÎÎÏ <link xlink:href="http://www.geocities.com/SiliconValley/Code/4704/universal.pdf">
	<acronym>MUST</acronym></link> ÐÏÚ×ÏÌÑÅÔ ÂÙÓÔÒÏ ÉÚÍÅÒÉÔØ
	ÜÎÔÒÏÐÉÀ ÐÏÓÌÅÄÏ×ÁÔÅÌØÎÏÇÏ ÎÁÂÏÒÁ ÄÁÎÎÙÈ.  éÓÐÏÌØÚÕÅÍÙÊ
	ÁÌÇÏÒÉÔÍ ÐÏÈÏÖ ÎÁ ÁÌÇÏÒÉÔÍ ÓÖÁÔÉÑ.  <link linkend="code">÷
	ÐÒÉÌÏÖÅÎÉÉ</link> ÐÒÉ×ÅģΠÉÓÈÏÄÎÙÊ ËÏÄ, ÐÏÚ×ÏÌÑÀÝÉÊ ÉÚÍÅÒÑÔØ
	ÜÎÔÒÏÐÉÀ ÐÏÓÌÅÄÏ×ÁÔÅÌØÎÙÈ ËÕÓËÏ× ÄÁÎÎÙÈ ÒÁÚÍÅÒÏÍ ÏËÏÌÏ
	ÞÅÔ×ÅÒÔÉ ÍÅÇÁÂÁÊÔÁ.</para>
    </sect2>

    <sect2 xml:id="tcpdump">
      <title>Tcpdump</title>

      <para>åÝ£ ÎÁÍ ÎÕÖÅÎ ÓÐÏÓÏ ÓÏÈÒÁÎÅÎÉÑ ÉÎÆÏÒÍÁÃÉÉ,
	ÐÒÏÈÏÄÑÝÅÊ ÞÅÒÅÚ ÉÎÔÅÒÆÅÊÓ.  ðÒÏÇÒÁÍÍÁ &man.tcpdump.1;
	ÐÏÚ×ÏÌÑÅÔ ÓÄÅÌÁÔØ ÜÔÏ × ÓÌÕÞÁÅ, ÅÓÌÉ ÷Ù <link linkend="kernel">ÓËÏÎÆÉÇÕÒÉÒÏ×ÁÌÉ Ó×Ï£ ÑÄÒÏ</link> Ó
	ÐÏÄÄÅÒÖËÏÊ <emphasis>ðÁËÅÔÎÏÇÏ æÉÌØÔÒÁ âÅÒËÌÉ (Berkeley Packet
	Filter)</emphasis>.</para>

      <para>ëÏÍÁÎÄÁ</para>

      <screen><userinput>tcpdump -c 4000 -s 10000 -w dumpfile.bin</userinput></screen>

      <para>ÓÏÈÒÁÎÉÔ 4000 ÐÁËÅÔÏ× × ÆÁÊÌ
	<replaceable>dumpfile.bin</replaceable>.  ÷ ÄÁÎÎÏÍ ÐÒÉÍÅÒÅ ÏÂߣÍ
	ÚÁÐÉÓÙ×ÁÅÍÏÊ ÉÎÆÏÒÍÁÃÉÉ × ËÁÖÄÏÍ ÐÁËÅÔÅ ÎÅ ÍÏÖÅÔ ÐÒÅ×ÙÛÁÔØ
	10,000 ÂÁÊÔÏ×.</para>
    </sect2>
  </sect1>

  <sect1 xml:id="experiment">
    <title>üËÓÐÅÒÉÍÅÎÔ</title>

    <para>ðÏ×ÔÏÒÉÔÅ ÓÌÅÄÕÀÝÉÅ ÛÁÇÉ ÜËÓÐÅÒÉÍÅÎÔÁ:</para>

    <procedure>
      <step>
	<para>ïÔËÒÏÊÔÅ Ä×Á ÏËÎÁ ÔÅÒÍÉÎÁÌÁ É Ó×ÑÖÉÔÅÓØ × ÏÄÎÏÍ ÉÚ ÎÉÈ Ó
	  ËÁËÉÍ-ÎÉÂÕÄØ ËÏÍÐØÀÔÅÒÏÍ ÞÅÒÅÚ ËÁÎÁÌ IPsec, Á × ÄÒÕÇÏÍ &mdash; Ó
	  ÏÂÙÞÎÙÍ, <quote>ÎÅÚÁÝÉÝ£ÎÎÙÍ</quote> ËÏÍÐØÀÔÅÒÏÍ.</para>
      </step>

      <step>
	<para>ôÅÐÅÒØ ÎÁÞÎÉÔÅ <link linkend="tcpdump">ÓÏÈÒÁÎÑÔØ
	  ÐÁËÅÔÙ</link>.</para>
      </step>

      <step>
	<para>÷ <quote>ÛÉÆÒÏ×ÁÎÎÏÍ</quote> ÏËÎÅ ÚÁÐÕÓÔÉÔÅ ËÏÍÁÎÄÕ &unix;
	  &man.yes.1;, ËÏÔÏÒÁÑ ÂÕÄÅÔ ×ÙÄÁ×ÁÔØ ÂÅÓËÏÎÅÞÎÙÊ
	  ÐÏÔÏË ÓÉÍ×ÏÌÏ× <literal>y</literal>.  îÅÍÎÏÖËÏ ÐÏÄÏÖÄÉÔÅ É
	  ÚÁ×ÅÒÛÉÔŠţ.  úÁÔÅÍ ÐÅÒÅËÌÀÞÉÔÅÓØ × ÏÂÙÞÎÏÅ ÏËÎÏ (ÎÅ
	  ÉÓÐÏÌØÚÕÀÝÅÅ ËÁÎÁÌ IPsec) É ÓÄÅÌÁÊÔÅ ÔÏ ÖÅ ÓÁÍÏÅ.</para>
      </step>

      <step>
	<para>úÁËÌÀÞÉÔÅÌØÎÙÊ ÜÔÁÐ: ÚÁÐÕÓÔÉÔÅ <link linkend="code">
	    MUST</link>, ÐÅÒÅÄÁ× ÅÍÕ ÄÌÑ ÏÂÒÁÂÏÔËÉ ÔÏÌØËÏ ÞÔÏ
	  ÓÏÈÒÁΣÎÎÙÅ ÐÁËÅÔÙ ÞÅÒÅÚ ËÏÍÁÎÄÎÕÀ ÓÔÒÏËÕ.  ÷Ù ÄÏÌÖÎÙ
	  Õ×ÉÄÅÔØ ÞÔÏ-ÔÏ ×ÒÏÄÅ ÉÚÏÂÒÁÖ£ÎÎÏÇÏ ÞÕÔØ ÎÉÖÅ.  úÁÍÅÔØÔÅ, ÞÔÏ
	  ÂÅÚÏÐÁÓÎÏÅ ÓÏÅÄÉÎÅÎÉÅ ÉÍÅÅÔ 93% (6,7) ÏÔ ÏÖÉÄÁÅÍÏÇÏ ÚÎÁÞÅÎÉÑ
	  (7,18), Á ÏÂÙÞÎÏÅ ÓÏÅÄÉÎÅÎÉÅ &mdash; ×ÓÅÇÏ ÌÉÛØ 29%
	  (2,1).</para>

	<screen>&prompt.user; <userinput>tcpdump -c 4000 -s 10000 -w ipsecdemo.bin</userinput>
&prompt.user; <userinput>uliscan ipsecdemo.bin</userinput>

Uliscan 21 Dec 98
L=8 256 258560
Measuring file ipsecdemo.bin
Init done
Expected value for L=8 is 7.1836656
6.9396 --------------------------------------------------------
6.6177 -----------------------------------------------------
6.4100 ---------------------------------------------------
2.1101 -----------------
2.0838 -----------------
2.0983 -----------------</screen>
      </step>
    </procedure>
  </sect1>

  <sect1 xml:id="caveat">
    <title>úÁÍÅÞÁÎÉÅ</title>

    <para>üÔÏÔ ÜËÓÐÅÒÉÍÅÎÔ ÐÏËÁÚÙ×ÁÅÔ, ÞÔÏ IPsec
      <emphasis>ÄÅÊÓÔ×ÉÔÅÌØÎÏ</emphasis> ÒÁÓÐÒÅÄÅÌÑÅÔ ÐÅÒÅÄÁ×ÁÅÍÙÅ
      ÂÁÊÔÙ ÐÏ ÏÂÌÁÓÔÉ ÏÐÒÅÄÅÌÅÎÉÑ <emphasis>ÒÁ×ÎÏÍÅÒÎÏ</emphasis>,
      ËÁË É ÌÀÂÏÅ ÄÒÕÇÏÅ ÛÉÆÒÏ×ÁÎÉÅ.  ïÄÎÁËÏ ÜÔÏÔ ÍÅÔÏÄ <emphasis>ÎÅ
      ÍÏÖÅÔ</emphasis> ÏÂÎÁÒÕÖÉÔØ ÍÎÏÖÅÓÔ×Ï ÄÒÕÇÉÈ ÉÚßÑÎÏ× × ÓÉÓÔÅÍÅ
      (ÈÏÔÑ Ñ ÔÁËÏ×ÙÈ ÎÅ ÚÎÁÀ).  äÌÑ ÐÒÉÍÅÒÁ ÍÏÖÎÏ ÐÒÉ×ÅÓÔÉ ÐÌÏÈÉÅ
      ÁÌÇÏÒÉÔÍÙ ÇÅÎÅÒÁÃÉÉ ÉÌÉ ÏÂÍÅÎÁ ËÌÀÞÁÍÉ, ÎÁÒÕÛÅÎÉÅ
      ËÏÎÆÉÄÅÎÃÉÁÌØÎÏÓÔÉ ÄÁÎÎÙÈ ÉÌÉ ËÌÀÞÅÊ, ÉÓÐÏÌØÚÏ×ÁÎÉÅ ÓÌÁÂÙÈ ×
      ËÒÉÐÔÏÇÒÁÆÉÞÅÓËÏÍ ÓÍÙÓÌÅ ÁÌÇÏÒÉÔÍÏ×, ×ÚÌÏÍ ÑÄÒÁ É Ô. Ä.  éÚÕÞÁÊÔÅ
      ÉÓÈÏÄÎÙÊ ËÏÄ, ÕÚÎÁ×ÁÊÔÅ, ÞÔÏ ÔÁÍ ÐÒÏÉÓÈÏÄÉÔ.</para>
  </sect1>

  <sect1 xml:id="IPsec">
    <title>ïÐÒÅÄÅÌÅÎÉÅ IPsec</title>

    <para>IPsec ÐÒÅÄÓÔÁ×ÌÑÅÔ ÓÏÂÏÊ ÐÒÏÔÏËÏÌ ÂÅÚÏÐÁÓÎÏÇÏ ÏÂÍÅÎÁ
      ÉÎÆÏÒÍÁÃÉÅÊ ÐÏ Internet.  óÕÝÅÓÔ×ÕÅÔ × ×ÉÄÅ ÒÁÓÛÉÒÅÎÉÑ Ë IPv4;
      Ñ×ÌÑÅÔÓÑ ÎÅÏÔßÅÍÌÅÍÏÊ ÞÁÓÔØÀ IPv6.  óÏÄÅÒÖÉÔ × ÓÅÂÅ ÐÒÏÔÏËÏÌ
      ÛÉÆÒÏ×ÁÎÉÑ É ÁÕÔÅÎÔÉÆÉËÁÃÉÉ ÎÁ ÕÒÏ×ÎÅ IP (ÍÅÖÍÁÛÉÎÎÏÅ
      <quote>host-to-host</quote> ×ÚÁÉÍÏÄÅÊÓÔ×ÉÅ).  SSL ÚÁÝÉÝÁÅÔ
      ÔÏÌØËÏ ÌÉÛØ ËÏÎËÒÅÔÎÙÊ ÐÒÉËÌÁÄÎÏÊ ÓÏËÅÔ;
      <application>SSH</application> ÚÁÝÉÝÁÅÔ ×ÈÏÄ ÎÁ ÍÁÛÉÎÕ;
      <application>PGP</application> ÚÁÝÉÝÁÅÔ ÏÐÒÅÄÅÌ£ÎÎÙÊ ÆÁÊÌ ÉÌÉ
      ÐÉÓØÍÏ.  IPsec ÛÉÆÒÕÅÔ ×ÓÀ ÉÎÆÏÒÍÁÃÉÀ, ÐÅÒÅÄÁ×ÁÅÍÕÀ ÍÅÖÄÕ Ä×ÕÍÑ
      ÍÁÛÉÎÁÍÉ.</para>
  </sect1>

  <sect1 xml:id="ipsec-install">
    <title>õÓÔÁÎÏ×ËÁ IPsec</title>

    <para>âÏÌØÛÉÎÓÔ×Ï ÓÏ×ÒÅÍÅÎÎÙÈ ×ÅÒÓÉÊ FreeBSD ÕÖÅ ÉÍÅÀÔ ÐÏÄÄÅÒÖËÕ
      IPsec.  ÷ÅÒÏÑÔÎÏ, ÷Ù ÄÏÌÖÎÙ ÂÕÄÅÔÅ ÌÉÛØ ÄÏÂÁ×ÉÔØ ÏÐÃÉÀ
      <option>IPsec</option> × ËÏÎÆÉÇÕÒÁÃÉÏÎÎÙÊ ÆÁÊÌ ÑÄÒÁ, É ÐÏÓÌÅ
      ÓÂÏÒËÉ É ÉÎÓÔÁÌÌÑÃÉÉ ÎÏ×ÏÇÏ ÑÄÒÁ, ÓËÏÎÆÉÇÕÒÉÒÏ×ÁÔØ ÓÏÅÄÉÎÅÎÉÅ
      IPsec Ó ÐÏÍÏÝØÀ ËÏÍÁÎÄÙ &man.setkey.8;.</para>

    <para>âÏÌÅÅ ÐÏÄÒÏÂÎÏ Ï ÔÏÍ, ËÁË ÚÁÐÕÓÔÉÔØ IPsec ×Ï FreeBSD ÍÏÖÎÏ
      ÐÒÏÞÅÓÔØ × <link xlink:href="&url.books.handbook;/ipsec.html">òÕËÏ×ÏÄÓÔ×Å
      ÐÏÌØÚÏ×ÁÔÅÌÑ</link>.</para>
  </sect1>

  <sect1 xml:id="kernel">
    <title>src/sys/i386/conf/KERNELNAME</title>

    <para>äÌÑ ÔÏÇÏ, ÞÔÏÂÙ ÚÁÈ×ÁÔÙ×ÁÔØ ÓÅÔÅ×ÏÊ ÔÒÁÆÉË ÐÒÉ ÐÏÍÏÝÉ
      &man.tcpdump.1;, ÓÌÅÄÕÀÝÉÅ ÓÔÒÏËÉ ÄÏÌÖÎÙ ÐÒÉÓÕÔÓÔ×Ï×ÁÔØ
      × ËÏÎÆÉÇÕÒÁÃÉÏÎÎÏÍ ÆÁÊÌÅ ÑÄÒÁ.  îÅ
      ÚÁÂÕÄØÔÅ ÐÏÓÌÅ ÍÏÄÉÆÉËÁÃÉÉ ÚÁÐÕÓÔÉÔØ &man.config.8;, É, ËÁË
      ÏÂÙÞÎÏ, ÐÅÒÅÓÏÂÒÁÔØ É ÕÓÔÁÎÏ×ÉÔØ ÎÏ×ÏÅ ÑÄÒÏ.</para>

    <programlisting>device	bpf</programlisting>
  </sect1>

  <sect1 xml:id="code">
    <title>õÎÉ×ÅÒÓÁÌØÎÙÊ óÔÁÔÉÓÔÉÞÅÓËÉÊ ôÅÓÔ íÁÕÒÅÒÁ (ÒÁÚÍÅÒ ÂÌÏËÁ
      &mdash; 8 ÂÉÔ)</title>

    <para>ïÒÉÇÉÎÁÌ ÎÉÖÅÐÒÉ×ÅÄ£ÎÎÏÇÏ ËÏÄÁ ÎÁÈÏÄÉÔÓÑ ÐÏ <link xlink:href="http://www.geocities.com/SiliconValley/Code/4704/uliscanc.txt">
        ÜÔÏÍÕ ÁÄÒÅÓÕ</link>.</para>

    <programlisting>/*
  ULISCAN.c   ---blocksize of 8

  1 Oct 98
  1 Dec 98
  21 Dec 98       uliscan.c derived from ueli8.c

  This version has // comments removed for Sun cc

  This implements Ueli M Maurer's "Universal Statistical Test for Random
  Bit Generators" using L=8

  Accepts a filename on the command line; writes its results, with other
  info, to stdout.

  Handles input file exhaustion gracefully.

  Ref: J. Cryptology v 5 no 2, 1992 pp 89-105
  also on the web somewhere, which is where I found it.

  -David Honig
  honig@sprynet.com

  Usage:
  ULISCAN filename
  outputs to stdout
*/

#define L 8
#define V (1&lt;&lt;L)
#define Q (10*V)
#define K (100   *Q)
#define MAXSAMP (Q + K)

#include &lt;stdio.h&gt;
#include &lt;math.h&gt;

int main(argc, argv)
int argc;
char **argv;
{
  FILE *fptr;
  int i,j;
  int b, c;
  int table[V];
  double sum = 0.0;
  int iproduct = 1;
  int run;

  extern double   log(/* double x */);

  printf("Uliscan 21 Dec 98 \nL=%d %d %d \n", L, V, MAXSAMP);

  if (argc &lt; 2) {
    printf("Usage: Uliscan filename\n");
    exit(-1);
  } else {
    printf("Measuring file %s\n", argv[1]);
  }

  fptr = fopen(argv[1],"rb");

  if (fptr == NULL) {
    printf("Can't find %s\n", argv[1]);
    exit(-1);
  }

  for (i = 0; i &lt; V; i++) {
    table[i] = 0;
  }

  for (i = 0; i &lt; Q; i++) {
    b = fgetc(fptr);
    table[b] = i;
  }

  printf("Init done\n");

  printf("Expected value for L=8 is 7.1836656\n");

  run = 1;

  while (run) {
    sum = 0.0;
    iproduct = 1;

    if (run)
      for (i = Q; run &amp;&amp; i &lt; Q + K; i++) {
        j = i;
        b = fgetc(fptr);

        if (b &lt; 0)
          run = 0;

        if (run) {
          if (table[b] &gt; j)
            j += K;

          sum += log((double)(j-table[b]));

          table[b] = i;
        }
      }

    if (!run)
      printf("Premature end of file; read %d blocks.\n", i - Q);

    sum = (sum/((double)(i - Q))) /  log(2.0);
    printf("%4.4f ", sum);

    for (i = 0; i &lt; (int)(sum*8.0 + 0.50); i++)
      printf("-");

    printf("\n");

    /* refill initial table */
    if (0) {
      for (i = 0; i &lt; Q; i++) {
        b = fgetc(fptr);
        if (b &lt; 0) {
          run = 0;
        } else {
          table[b] = i;
        }
      }
    }
  }
}</programlisting>
  </sect1>
</article>