Edit File: telnetlib.html
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <title>20.14. telnetlib — Telnet client — Python v2.6.6 documentation</title> <link rel="stylesheet" href="../_static/default.css" type="text/css" /> <link rel="stylesheet" href="../_static/pygments.css" type="text/css" /> <script type="text/javascript"> var DOCUMENTATION_OPTIONS = { URL_ROOT: '../', VERSION: '2.6.6', COLLAPSE_MODINDEX: false, FILE_SUFFIX: '.html', HAS_SOURCE: true }; </script> <script type="text/javascript" src="../_static/jquery.js"></script> <script type="text/javascript" src="../_static/doctools.js"></script> <link rel="search" type="application/opensearchdescription+xml" title="Search within Python v2.6.6 documentation" href="../_static/opensearch.xml"/> <link rel="author" title="About these documents" href="../about.html" /> <link rel="copyright" title="Copyright" href="../copyright.html" /> <link rel="top" title="Python v2.6.6 documentation" href="../index.html" /> <link rel="up" title="20. 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Internet Protocols and Support</a> »</li> </ul> </div> <div class="document"> <div class="documentwrapper"> <div class="bodywrapper"> <div class="body"> <div class="section" id="module-telnetlib"> <h1>20.14. <tt class="xref docutils literal"><span class="pre">telnetlib</span></tt> — Telnet client<a class="headerlink" href="#module-telnetlib" title="Permalink to this headline">¶</a></h1> <p id="index-653">The <tt class="xref docutils literal"><span class="pre">telnetlib</span></tt> module provides a <a title="telnetlib.Telnet" class="reference internal" href="#telnetlib.Telnet"><tt class="xref docutils literal"><span class="pre">Telnet</span></tt></a> class that implements the Telnet protocol. See <span class="target" id="index-654"></span><a class="reference external" href="http://tools.ietf.org/html/rfc854.html"><strong>RFC 854</strong></a> for details about the protocol. In addition, it provides symbolic constants for the protocol characters (see below), and for the telnet options. The symbolic names of the telnet options follow the definitions in <tt class="docutils literal"><span class="pre">arpa/telnet.h</span></tt>, with the leading <tt class="docutils literal"><span class="pre">TELOPT_</span></tt> removed. For symbolic names of options which are traditionally not included in <tt class="docutils literal"><span class="pre">arpa/telnet.h</span></tt>, see the module source itself.</p> <p>The symbolic constants for the telnet commands are: IAC, DONT, DO, WONT, WILL, SE (Subnegotiation End), NOP (No Operation), DM (Data Mark), BRK (Break), IP (Interrupt process), AO (Abort output), AYT (Are You There), EC (Erase Character), EL (Erase Line), GA (Go Ahead), SB (Subnegotiation Begin).</p> <dl class="class"> <dt id="telnetlib.Telnet"> <em class="property">class </em><tt class="descclassname">telnetlib.</tt><tt class="descname">Telnet</tt><big>(</big><span class="optional">[</span><em>host</em><span class="optional">[</span>, <em>port</em><span class="optional">[</span>, <em>timeout</em><span class="optional">]</span><span class="optional">]</span><span class="optional">]</span><big>)</big><a class="headerlink" href="#telnetlib.Telnet" title="Permalink to this definition">¶</a></dt> <dd><p><a title="telnetlib.Telnet" class="reference internal" href="#telnetlib.Telnet"><tt class="xref docutils literal"><span class="pre">Telnet</span></tt></a> represents a connection to a Telnet server. The instance is initially not connected by default; the <a title="open" class="reference external" href="functions.html#open"><tt class="xref docutils literal"><span class="pre">open()</span></tt></a> method must be used to establish a connection. Alternatively, the host name and optional port number can be passed to the constructor, to, in which case the connection to the server will be established before the constructor returns. The optional <em>timeout</em> parameter specifies a timeout in seconds for blocking operations like the connection attempt (if not specified, the global default timeout setting will be used).</p> <p>Do not reopen an already connected instance.</p> <p>This class has many <tt class="xref docutils literal"><span class="pre">read_*()</span></tt> methods. Note that some of them raise <a title="exceptions.EOFError" class="reference external" href="exceptions.html#exceptions.EOFError"><tt class="xref docutils literal"><span class="pre">EOFError</span></tt></a> when the end of the connection is read, because they can return an empty string for other reasons. See the individual descriptions below.</p> <p class="versionchanged"> <span class="versionmodified">Changed in version 2.6: </span><em>timeout</em> was added.</p> </dd></dl> <div class="admonition-see-also admonition seealso"> <p class="first admonition-title">See also</p> <dl class="last docutils"> <dt><span class="target" id="index-655"></span><a class="reference external" href="http://tools.ietf.org/html/rfc854.html"><strong>RFC 854</strong></a> - Telnet Protocol Specification</dt> <dd>Definition of the Telnet protocol.</dd> </dl> </div> <div class="section" id="telnet-objects"> <span id="id1"></span><h2>20.14.1. Telnet Objects<a class="headerlink" href="#telnet-objects" title="Permalink to this headline">¶</a></h2> <p><a title="telnetlib.Telnet" class="reference internal" href="#telnetlib.Telnet"><tt class="xref docutils literal"><span class="pre">Telnet</span></tt></a> instances have the following methods:</p> <dl class="method"> <dt id="telnetlib.Telnet.read_until"> <tt class="descclassname">Telnet.</tt><tt class="descname">read_until</tt><big>(</big><em>expected</em><span class="optional">[</span>, <em>timeout</em><span class="optional">]</span><big>)</big><a class="headerlink" href="#telnetlib.Telnet.read_until" title="Permalink to this definition">¶</a></dt> <dd><p>Read until a given string, <em>expected</em>, is encountered or until <em>timeout</em> seconds have passed.</p> <p>When no match is found, return whatever is available instead, possibly the empty string. Raise <a title="exceptions.EOFError" class="reference external" href="exceptions.html#exceptions.EOFError"><tt class="xref docutils literal"><span class="pre">EOFError</span></tt></a> if the connection is closed and no cooked data is available.</p> </dd></dl> <dl class="method"> <dt id="telnetlib.Telnet.read_all"> <tt class="descclassname">Telnet.</tt><tt class="descname">read_all</tt><big>(</big><big>)</big><a class="headerlink" href="#telnetlib.Telnet.read_all" title="Permalink to this definition">¶</a></dt> <dd>Read all data until EOF; block until connection closed.</dd></dl> <dl class="method"> <dt id="telnetlib.Telnet.read_some"> <tt class="descclassname">Telnet.</tt><tt class="descname">read_some</tt><big>(</big><big>)</big><a class="headerlink" href="#telnetlib.Telnet.read_some" title="Permalink to this definition">¶</a></dt> <dd>Read at least one byte of cooked data unless EOF is hit. Return <tt class="docutils literal"><span class="pre">''</span></tt> if EOF is hit. Block if no data is immediately available.</dd></dl> <dl class="method"> <dt id="telnetlib.Telnet.read_very_eager"> <tt class="descclassname">Telnet.</tt><tt class="descname">read_very_eager</tt><big>(</big><big>)</big><a class="headerlink" href="#telnetlib.Telnet.read_very_eager" title="Permalink to this definition">¶</a></dt> <dd><p>Read everything that can be without blocking in I/O (eager).</p> <p>Raise <a title="exceptions.EOFError" class="reference external" href="exceptions.html#exceptions.EOFError"><tt class="xref docutils literal"><span class="pre">EOFError</span></tt></a> if connection closed and no cooked data available. Return <tt class="docutils literal"><span class="pre">''</span></tt> if no cooked data available otherwise. Do not block unless in the midst of an IAC sequence.</p> </dd></dl> <dl class="method"> <dt id="telnetlib.Telnet.read_eager"> <tt class="descclassname">Telnet.</tt><tt class="descname">read_eager</tt><big>(</big><big>)</big><a class="headerlink" href="#telnetlib.Telnet.read_eager" title="Permalink to this definition">¶</a></dt> <dd><p>Read readily available data.</p> <p>Raise <a title="exceptions.EOFError" class="reference external" href="exceptions.html#exceptions.EOFError"><tt class="xref docutils literal"><span class="pre">EOFError</span></tt></a> if connection closed and no cooked data available. Return <tt class="docutils literal"><span class="pre">''</span></tt> if no cooked data available otherwise. Do not block unless in the midst of an IAC sequence.</p> </dd></dl> <dl class="method"> <dt id="telnetlib.Telnet.read_lazy"> <tt class="descclassname">Telnet.</tt><tt class="descname">read_lazy</tt><big>(</big><big>)</big><a class="headerlink" href="#telnetlib.Telnet.read_lazy" title="Permalink to this definition">¶</a></dt> <dd><p>Process and return data already in the queues (lazy).</p> <p>Raise <a title="exceptions.EOFError" class="reference external" href="exceptions.html#exceptions.EOFError"><tt class="xref docutils literal"><span class="pre">EOFError</span></tt></a> if connection closed and no data available. Return <tt class="docutils literal"><span class="pre">''</span></tt> if no cooked data available otherwise. Do not block unless in the midst of an IAC sequence.</p> </dd></dl> <dl class="method"> <dt id="telnetlib.Telnet.read_very_lazy"> <tt class="descclassname">Telnet.</tt><tt class="descname">read_very_lazy</tt><big>(</big><big>)</big><a class="headerlink" href="#telnetlib.Telnet.read_very_lazy" title="Permalink to this definition">¶</a></dt> <dd><p>Return any data available in the cooked queue (very lazy).</p> <p>Raise <a title="exceptions.EOFError" class="reference external" href="exceptions.html#exceptions.EOFError"><tt class="xref docutils literal"><span class="pre">EOFError</span></tt></a> if connection closed and no data available. Return <tt class="docutils literal"><span class="pre">''</span></tt> if no cooked data available otherwise. This method never blocks.</p> </dd></dl> <dl class="method"> <dt id="telnetlib.Telnet.read_sb_data"> <tt class="descclassname">Telnet.</tt><tt class="descname">read_sb_data</tt><big>(</big><big>)</big><a class="headerlink" href="#telnetlib.Telnet.read_sb_data" title="Permalink to this definition">¶</a></dt> <dd><p>Return the data collected between a SB/SE pair (suboption begin/end). The callback should access these data when it was invoked with a <tt class="docutils literal"><span class="pre">SE</span></tt> command. This method never blocks.</p> <p class="versionadded"> <span class="versionmodified">New in version 2.3.</span></p> </dd></dl> <dl class="method"> <dt id="telnetlib.Telnet.open"> <tt class="descclassname">Telnet.</tt><tt class="descname">open</tt><big>(</big><em>host</em><span class="optional">[</span>, <em>port</em><span class="optional">[</span>, <em>timeout</em><span class="optional">]</span><span class="optional">]</span><big>)</big><a class="headerlink" href="#telnetlib.Telnet.open" title="Permalink to this definition">¶</a></dt> <dd><p>Connect to a host. The optional second argument is the port number, which defaults to the standard Telnet port (23). The optional <em>timeout</em> parameter specifies a timeout in seconds for blocking operations like the connection attempt (if not specified, the global default timeout setting will be used).</p> <p>Do not try to reopen an already connected instance.</p> <p class="versionchanged"> <span class="versionmodified">Changed in version 2.6: </span><em>timeout</em> was added.</p> </dd></dl> <dl class="method"> <dt id="telnetlib.Telnet.msg"> <tt class="descclassname">Telnet.</tt><tt class="descname">msg</tt><big>(</big><em>msg</em><span class="optional">[</span>, <em>*args</em><span class="optional">]</span><big>)</big><a class="headerlink" href="#telnetlib.Telnet.msg" title="Permalink to this definition">¶</a></dt> <dd>Print a debug message when the debug level is <tt class="docutils literal"><span class="pre">></span></tt> 0. If extra arguments are present, they are substituted in the message using the standard string formatting operator.</dd></dl> <dl class="method"> <dt id="telnetlib.Telnet.set_debuglevel"> <tt class="descclassname">Telnet.</tt><tt class="descname">set_debuglevel</tt><big>(</big><em>debuglevel</em><big>)</big><a class="headerlink" href="#telnetlib.Telnet.set_debuglevel" title="Permalink to this definition">¶</a></dt> <dd>Set the debug level. The higher the value of <em>debuglevel</em>, the more debug output you get (on <tt class="docutils literal"><span class="pre">sys.stdout</span></tt>).</dd></dl> <dl class="method"> <dt id="telnetlib.Telnet.close"> <tt class="descclassname">Telnet.</tt><tt class="descname">close</tt><big>(</big><big>)</big><a class="headerlink" href="#telnetlib.Telnet.close" title="Permalink to this definition">¶</a></dt> <dd>Close the connection.</dd></dl> <dl class="method"> <dt id="telnetlib.Telnet.get_socket"> <tt class="descclassname">Telnet.</tt><tt class="descname">get_socket</tt><big>(</big><big>)</big><a class="headerlink" href="#telnetlib.Telnet.get_socket" title="Permalink to this definition">¶</a></dt> <dd>Return the socket object used internally.</dd></dl> <dl class="method"> <dt id="telnetlib.Telnet.fileno"> <tt class="descclassname">Telnet.</tt><tt class="descname">fileno</tt><big>(</big><big>)</big><a class="headerlink" href="#telnetlib.Telnet.fileno" title="Permalink to this definition">¶</a></dt> <dd>Return the file descriptor of the socket object used internally.</dd></dl> <dl class="method"> <dt id="telnetlib.Telnet.write"> <tt class="descclassname">Telnet.</tt><tt class="descname">write</tt><big>(</big><em>buffer</em><big>)</big><a class="headerlink" href="#telnetlib.Telnet.write" title="Permalink to this definition">¶</a></dt> <dd>Write a string to the socket, doubling any IAC characters. This can block if the connection is blocked. May raise <a title="socket.error" class="reference external" href="socket.html#socket.error"><tt class="xref docutils literal"><span class="pre">socket.error</span></tt></a> if the connection is closed.</dd></dl> <dl class="method"> <dt id="telnetlib.Telnet.interact"> <tt class="descclassname">Telnet.</tt><tt class="descname">interact</tt><big>(</big><big>)</big><a class="headerlink" href="#telnetlib.Telnet.interact" title="Permalink to this definition">¶</a></dt> <dd>Interaction function, emulates a very dumb Telnet client.</dd></dl> <dl class="method"> <dt id="telnetlib.Telnet.mt_interact"> <tt class="descclassname">Telnet.</tt><tt class="descname">mt_interact</tt><big>(</big><big>)</big><a class="headerlink" href="#telnetlib.Telnet.mt_interact" title="Permalink to this definition">¶</a></dt> <dd>Multithreaded version of <a title="telnetlib.Telnet.interact" class="reference internal" href="#telnetlib.Telnet.interact"><tt class="xref docutils literal"><span class="pre">interact()</span></tt></a>.</dd></dl> <dl class="method"> <dt id="telnetlib.Telnet.expect"> <tt class="descclassname">Telnet.</tt><tt class="descname">expect</tt><big>(</big><em>list</em><span class="optional">[</span>, <em>timeout</em><span class="optional">]</span><big>)</big><a class="headerlink" href="#telnetlib.Telnet.expect" title="Permalink to this definition">¶</a></dt> <dd><p>Read until one from a list of a regular expressions matches.</p> <p>The first argument is a list of regular expressions, either compiled (<a title="re.RegexObject" class="reference external" href="re.html#re.RegexObject"><tt class="xref docutils literal"><span class="pre">re.RegexObject</span></tt></a> instances) or uncompiled (strings). The optional second argument is a timeout, in seconds; the default is to block indefinitely.</p> <p>Return a tuple of three items: the index in the list of the first regular expression that matches; the match object returned; and the text read up till and including the match.</p> <p>If end of file is found and no text was read, raise <a title="exceptions.EOFError" class="reference external" href="exceptions.html#exceptions.EOFError"><tt class="xref docutils literal"><span class="pre">EOFError</span></tt></a>. Otherwise, when nothing matches, return <tt class="docutils literal"><span class="pre">(-1,</span> <span class="pre">None,</span> <span class="pre">text)</span></tt> where <em>text</em> is the text received so far (may be the empty string if a timeout happened).</p> <p>If a regular expression ends with a greedy match (such as <tt class="docutils literal"><span class="pre">.*</span></tt>) or if more than one expression can match the same input, the results are indeterministic, and may depend on the I/O timing.</p> </dd></dl> <dl class="method"> <dt id="telnetlib.Telnet.set_option_negotiation_callback"> <tt class="descclassname">Telnet.</tt><tt class="descname">set_option_negotiation_callback</tt><big>(</big><em>callback</em><big>)</big><a class="headerlink" href="#telnetlib.Telnet.set_option_negotiation_callback" title="Permalink to this definition">¶</a></dt> <dd>Each time a telnet option is read on the input flow, this <em>callback</em> (if set) is called with the following parameters : callback(telnet socket, command (DO/DONT/WILL/WONT), option). No other action is done afterwards by telnetlib.</dd></dl> </div> <div class="section" id="telnet-example"> <span id="id2"></span><h2>20.14.2. Telnet Example<a class="headerlink" href="#telnet-example" title="Permalink to this headline">¶</a></h2> <p>A simple example illustrating typical use:</p> <div class="highlight-python"><div class="highlight"><pre><span class="kn">import</span> <span class="nn">getpass</span> <span class="kn">import</span> <span class="nn">sys</span> <span class="kn">import</span> <span class="nn">telnetlib</span> <span class="n">HOST</span> <span class="o">=</span> <span class="s">"localhost"</span> <span class="n">user</span> <span class="o">=</span> <span class="nb">raw_input</span><span class="p">(</span><span class="s">"Enter your remote account: "</span><span class="p">)</span> <span class="n">password</span> <span class="o">=</span> <span class="n">getpass</span><span class="o">.</span><span class="n">getpass</span><span class="p">()</span> <span class="n">tn</span> <span class="o">=</span> <span class="n">telnetlib</span><span class="o">.</span><span class="n">Telnet</span><span class="p">(</span><span class="n">HOST</span><span class="p">)</span> <span class="n">tn</span><span class="o">.</span><span class="n">read_until</span><span class="p">(</span><span class="s">"login: "</span><span class="p">)</span> <span class="n">tn</span><span class="o">.</span><span class="n">write</span><span class="p">(</span><span class="n">user</span> <span class="o">+</span> <span class="s">"</span><span class="se">\n</span><span class="s">"</span><span class="p">)</span> <span class="k">if</span> <span class="n">password</span><span class="p">:</span> <span class="n">tn</span><span class="o">.</span><span class="n">read_until</span><span class="p">(</span><span class="s">"Password: "</span><span class="p">)</span> <span class="n">tn</span><span class="o">.</span><span class="n">write</span><span class="p">(</span><span class="n">password</span> <span class="o">+</span> <span class="s">"</span><span class="se">\n</span><span class="s">"</span><span class="p">)</span> <span class="n">tn</span><span class="o">.</span><span class="n">write</span><span class="p">(</span><span class="s">"ls</span><span class="se">\n</span><span class="s">"</span><span class="p">)</span> <span class="n">tn</span><span class="o">.</span><span class="n">write</span><span class="p">(</span><span class="s">"exit</span><span class="se">\n</span><span class="s">"</span><span class="p">)</span> <span class="k">print</span> <span class="n">tn</span><span class="o">.</span><span class="n">read_all</span><span class="p">()</span> </pre></div> </div> </div> </div> </div> </div> </div> <div class="sphinxsidebar"> <div class="sphinxsidebarwrapper"> <h3><a href="../contents.html">Table Of Contents</a></h3> <ul> <li><a class="reference external" href="#">20.14. <tt class="docutils literal"><span class="pre">telnetlib</span></tt> — Telnet client</a><ul> <li><a class="reference external" href="#telnet-objects">20.14.1. Telnet Objects</a></li> <li><a class="reference external" href="#telnet-example">20.14.2. Telnet Example</a></li> </ul> </li> </ul> <h4>Previous topic</h4> <p class="topless"><a href="smtpd.html" title="previous chapter">20.13. <tt class="docutils literal docutils literal docutils literal"><span class="pre">smtpd</span></tt> — SMTP Server</a></p> <h4>Next topic</h4> <p class="topless"><a href="uuid.html" title="next chapter">20.15. <tt class="docutils literal"><span class="pre">uuid</span></tt> — UUID objects according to RFC 4122</a></p> <h3>This Page</h3> <ul class="this-page-menu"> <li><a href="../bugs.html">Report a Bug</a></li> <li><a href="../_sources/library/telnetlib.txt" rel="nofollow">Show Source</a></li> </ul> <div id="searchbox" style="display: none"> <h3>Quick search</h3> <form class="search" action="../search.html" method="get"> <input type="text" name="q" size="18" /> <input type="submit" value="Go" /> <input type="hidden" name="check_keywords" value="yes" /> <input type="hidden" name="area" value="default" /> </form> <p class="searchtip" style="font-size: 90%"> Enter search terms or a module, class or function name. </p> </div> <script type="text/javascript">$('#searchbox').show(0);</script> </div> </div> <div class="clearer"></div> </div> <div class="related"> <h3>Navigation</h3> <ul> <li class="right" style="margin-right: 10px"> <a href="../genindex.html" title="General Index" >index</a></li> <li class="right" > <a href="../modindex.html" title="Global Module Index" >modules</a> |</li> <li class="right" > <a href="uuid.html" title="20.15. uuid — UUID objects according to RFC 4122" >next</a> |</li> <li class="right" > <a href="smtpd.html" title="20.13. smtpd — SMTP Server" >previous</a> |</li> <li><img src="../_static/py.png" alt="" style="vertical-align: middle; margin-top: -1px"/></li> <li><a href="../index.html">Python v2.6.6 documentation</a> »</li> <li><a href="index.html" >The Python Standard Library</a> »</li> <li><a href="internet.html" >20. 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