doc/help/network.html

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   5     <title>Using Network Printers</title>
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   9     <h1 class="title">Using Network Printers</h1>
  10
  11     <p>This help document describes how to discover, configure, and use TCP/IP network printers with CUPS.</p>
  12
  13     <h2 class="title" id="AUTOMATIC">Automatic Configuration Using Bonjour</h2>
  14
  15     <p>Most network printers support a protocol known as Bonjour, which is a combination of zero-configuration networking ("ZeroConf"), multicast DNS (mDNS), and DNS service discovery (DNS-SD) standards published by the Internet Engineering Task Force (IETF), the same group that defined TCP/IP and all of the networking we use today.</p>
  16
  17     <p>A printer that supports Bonjour can be found automatically using the <code>dnssd</code> backend. Run the <code>lpinfo(8)</code> command to find your printer's URI:</p>
  18
  19     <pre class="command">lpinfo --include-schemes dnssd -v
  20 network dnssd://Acme%20Laser%20Pro._ipp._tcp.local./?uuid=545253fb-1cb7-4d8d-98ed-ab6cd607cea7
  21 network dnssd://Bar99._printer.tcp.local./?uuid=f9efff58-9086-4c95-accb-81dee876a475
  22 network dnssd://Example%20EX-42._ipps._tcp.local./?uuid=4a0c67ad-2824-4ddf-9115-7d4226c5fe65
  23 network dnssd://Foo%20Fighter-1969._pdl-datastream._tcp.local./?uuid=4e216bea-c3de-4f65-a710-c99e11c80d2b</pre>
  24
  25     <p>You can then <a href="admin.html#PRINTERS">add a printer</a> using the URI reported.</p>
  26
  27
  28     <h2 class="title" id="MANUAL">Manual Configuration Using IP Addresses</h2>
  29
  30     <p>You can also manually configure a printer using its Internet Protocol v4 (IPv4) address. This address is either configured manually ("static IP") through the printer's control panel or set using an automatic network protocol such as the Dynamic Host Control Protocol (DHCP) or ZeroConf.</p>
  31
  32     <blockquote><b>Note:</b> Configuring a printer using an IP address set using DHCP or ZeroConf is not recommended since the address will change every time the printer is turned on or after long periods of inactivity. Thus, every time the address changes you will need to modify the print queue using the <code>lpadmin</code> command.</blockquote>
  33
  34     <h3>Finding the IP Address</h3>
  35
  36     <p>You can normally find the IP address of a printer on the printer's control panel or by printing the configuration or status page. The <a href="#SNMP">Simple Network Management Protocol (SNMP)</a> can also be used to get the IP address remotely. To test that the IP address has been successfully assigned and that the printer is properly connected to your LAN or Wi-Fi network, type:</p>
  37
  38     <pre class="command">ping ip-address</pre>
  39
  40     <p>where "ip-address" is the address reported by the printer's control panel, configuration page, and/or status page. If the connection is working properly you will see something like:</p>
  41
  42     <pre class="command">ping 10.0.1.42
  43 PING 10.0.1.42 (10.0.1.42): 56 data bytes
  44 64 bytes from 10.0.1.42: icmp_seq=0 ttl=15 time=1.123 ms
  45 64 bytes from 10.0.1.42: icmp_seq=1 ttl=15 time=2.034 ms
  46 64 bytes from 10.0.1.42: icmp_seq=2 ttl=15 time=1.765 ms
  47 64 bytes from 10.0.1.42: icmp_seq=3 ttl=15 time=1.234 ms
  48 ...</pre>
  49
  50     <p>If the connection is not working properly you will see something like:</p>
  51
  52     <pre class="command">ping 10.0.1.42
  53 PING 10.0.1.42 (10.0.1.42): 56 data bytes
  54 Request timeout for icmp_seq 0
  55 Request timeout for icmp_seq 1
  56 ...</pre>
  57
  58     <p>Press <kbd>CTRL+C</kbd> to quit the <code>ping</code> command.</p>
  59
  60     <blockquote><b>Note:</b> If the command does not show responses from the printer, verify that the printer or print server is powered on and connected to the same LAN or Wi-Fi network as your computer. For LAN connections, also verify that your network cabling is good.</blockquote>
  61
  62
  63     <h3>Choosing a Network Protocol (Backend)</h3>
  64
  65     <p>CUPS supports most network printers using one of three TCP/IP-based protocols: <a href="#SOCKET">AppSocket</a>, <a href="#IPP">Internet Printing Protocol</a>, and <a href="#LPD">Line Printer Daemon</a>. The following sections describe the options for each of the backends.</p>
  66
  67
  68     <h4 id="SOCKET">AppSocket Protocol (aka JetDirect)</h4>
  69
  70     <p>The AppSocket protocol (sometimes also called the JetDirect protocol, owing to its origins with the HP JetDirect network interfaces) is the simplest and fastest network protocol used for printers. AppSocket printing normally happens over port 9100 and uses the <code>socket</code> backend. Device URIs for the <code>socket</code> backend look like this:</p>
  71
  72     <pre class="example">socket://ip-address
  73 socket://ip-address/?contimeout=30
  74 socket://ip-address/?waiteof=false
  75 socket://ip-address/?contimeout=30&amp;waiteof=false
  76 socket://ip-address:port-number/?...</pre>
  77
  78     <p>The "contimeout" option controls the number of seconds that the backend will wait to obtain a connection to the printer. The default is 1 week or 604800 seconds.</p>
  79
  80     <p>The "waiteof" option controls whether the <code>socket</code> backend waits for the printer to complete the printing of the job. The default is to wait (<code>waiteof=true</code>). Add <code>waiteof=false</code> to the URI to tell the backend not to wait.</p>
  81
  82     <blockquote><b>Note:</b> While the AppSocket protocol is simple and fast, it also offers no security and is often an attack vector with printers. Consider using the <a href="#IPP">Internet Printing Protocol</a> which supports encryption and other security features.</blockquote>
  83
  84
  85     <h4 id="IPP">Internet Printing Protocol (IPP)</h4>
  86
  87     <p>IPP is the only protocol that CUPS supports natively and is supported by most network printers and print servers. IPP supports encryption and other security features over port 631 and uses the <code>http</code> (Windows), <code>ipp</code>, and <code>ipps</code> backends. Device URIs for these backends look like this:</p>
  88
  89     <pre class="example">http://ip-address-or-hostname:port-number/printers/name/.printer</i>
  90 ipp://ip-address/ipp/print
  91 ipp://ip-address-or-hostname/printers/name
  92 ipps://ip-address/ipp/print
  93 ipps://ip-address:443/ipp/print
  94 ipps://ip-address-or-hostname/printers/name</pre>
  95
  96     <p>The backends supports many options, which are summarized in <a href="#TABLE2">Table 2</a>. Like all backends, options are added to the end of the URI using the URL form encoding format, for example:</p>
  97
  98     <pre class="example">ipp://10.0.1.42/ipp/print?version=1.1
  99 ipps://10.0.1.42:443/ipp/print?waitjob=false&amp;waitprinter=false</pre>
 100
 101     <div class="table"><table summary="IPP URI Options">
 102       <caption>Table 2: <A NAME="TABLE2">IPP URI Options</a></caption>
 103       <thead>
 104         <tr>
 105           <th>Option</th>
 106           <th>Description</th>
 107         </tr>
 108       </thead>
 109       <tbody>
 110         <tr>
 111           <td><code>contimeout=<I>seconds</I></code></td>
 112           <td>Specifies the number of seconds to wait for the connection to the printer to complete (default 1 week or 604800 seconds).</td>
 113         </tr>
 114         <tr>
 115           <td><code>encryption=always</code></td>
 116           <td>Specifies that the connection to the IPP printer should be encrypted using SSL.</td>
 117         </tr>
 118         <tr>
 119           <td><code>encryption=ifrequested</code></td>
 120           <td>Specifies that the connection to the IPP printer should only be encrypted if the printer requests it.</td>
 121         </tr>
 122         <tr>
 123           <td><code>encryption=never</code></td>
 124           <td>Specifies that the connection to the IPP printer should not be encrypted.</td>
 125         </tr>
 126         <tr>
 127           <td><code>encryption=required</code></td>
 128           <td>Specifies that the connection to the IPP printer should be encrypted using TLS.</td>
 129         </tr>
 130         <tr>
 131           <td><code>version=1.0</code></td>
 132           <td>Specifies that version 1.0 of the IPP protocol should be used instead of the default version 2.0.</td>
 133         </tr>
 134         <tr>
 135           <td><code>version=1.1</code></td>
 136           <td>Specifies that version 1.1 of the IPP protocol should be used instead of the default version 2.0.</td>
 137         </tr>
 138         <tr>
 139           <td><code>version=2.1</code></td>
 140           <td>Specifies that version 2.1 of the IPP protocol should be used instead of the default version 2.0.</td>
 141         </tr>
 142         <tr>
 143           <td><code>waitjob=false</code></td>
 144           <td>Specifies that the IPP backend should not wait for the job to complete.</td>
 145         </tr>
 146         <tr>
 147           <td><code>waitprinter=false</code></td>
 148           <td>Specifies that the IPP backend should not wait for the printer to become idle before sending the print job.</td>
 149         </tr>
 150       </tbody>
 151     </table></div>
 152
 153
 154     <h4 id="LPD">Line Printer Daemon (LPD) Protocol (aka lpr)</h4>
 155
 156     <p>LPD is the original network printing protocol created for the Berkeley UNIX line printer daemon (spooler) and is supported by many network printers. LPD printing normally happens over port 515 and uses the <code>lpd</code> backend. Device URIsfor the <code>lpd</code> backend look like this:</p>
 157
 158     <pre class="example">lpd://ip-address/queue
 159 lpd://ip-address/queue?format=l
 160 lpd://ip-address/queue?format=l&amp;reserve=rfc1179</pre>
 161
 162     <p><a href="#TABLE3">Table 3</a> summarizes the options supported by the <code>lpd</code> backend.</p>
 163
 164     <blockquote><b>Note:</b> Due to limitations in the LPD protocol, we do not recommend using it if the printer or server supports any of the other protocols. Like AppSocket, LPD offers no security and is a common attack vector. LPD also, by default, requires that the computer save a copy of the entire print job before sending it to the printer - this can result in gigabytes of print data being saved to disk before any printing happens, delaying print jobs and shortening the life of your mass storage device!</blockquote>
 165
 166     <div class="table"><table summary="LPD URI Options">
 167       <caption>Table 3: <A NAME="TABLE3">LPD URI Options</a></caption>
 168       <thead>
 169         <tr>
 170           <th>Option</th>
 171           <th>Description</th>
 172         </tr>
 173       </thead>
 174       <tbody>
 175         <tr>
 176           <td><code>banner=on</code></td>
 177           <td>Specifies that a banner page should be printed by the printer.</td>
 178         </tr>
 179         <tr>
 180           <td><code>contimeout=<I>seconds</I></code></td>
 181           <td>Specifies the number of seconds to wait for the connection to the printer to complete (default 1 week or 604800 seconds).</td>
 182         </tr>
 183         <tr>
 184           <td><code>format=f</code></td>
 185           <td>Specifies that the print data is a plain text file.</td>
 186         </tr>
 187         <tr>
 188           <td><code>format=o</code></td>
 189           <td>Specifies that the print data is a PostScript file.</td>
 190         </tr>
 191         <tr>
 192           <td><code>format=p</code></td>
 193           <td>Specifies that the print data is a plain text file that should be "pretty" printed with a header and footer.</td>
 194         </tr>
 195         <tr>
 196           <td><code>mode=stream</code></td>
 197           <td>Specifies that the backend should stream print data to the printer and not wait for confirmation that the job has been successfully printed.</td>
 198         </tr>
 199         <tr>
 200           <td><code>order=data,control</code></td>
 201           <td>Specifies that the print data files should be sent before the control file.</td>
 202         </tr>
 203         <tr>
 204           <td><code>reserve=none</code></td>
 205           <td>Specifies that the backend should not reserve a source port.</td>
 206         </tr>
 207         <tr>
 208           <td><code>reserve=rfc1179</code></td>
 209           <td>Specifies that the backend should reserve a source port from 721 to 731 as required by RFC 1179.</td>
 210         </tr>
 211         <tr>
 212           <td><code>sanitize_title=no</code></td>
 213           <td>Specifies that the job title string should not be restricted to ASCII alphanumeric and space characters.</td>
 214         </tr>
 215         <tr>
 216           <td><code>sanitize_title=yes</code></td>
 217           <td>Specifies that the job title string should be restricted to ASCII alphanumeric and space characters.</td>
 218         </tr>
 219         <tr>
 220           <td><code>timeout=<I>seconds</I></code></td>
 221           <td>Specifies the number of seconds to wait for LPD commands to complete (default 5 minutes or 300 seconds).</td>
 222         </tr>
 223       </tbody>
 224     </table></div>
 225
 226
 227     <h2 class="title" id="SNMP">Finding Printers Using SNMP</h2>
 228
 229     <p>Whenever you view the administration web page or a list of supported device URIs, the <code>snmp</code> backend can probe the local network(s) using Simple Network Management Protocol (SNMP) v1 broadcasts. Printers that respond to these broadcasts are then interrogated for the make, model, and supported protocols, yielding a device URI that can be used to add the printer.</p>
 230
 231     <p>The <a href="man-cups-snmp.conf.html"><var>/etc/cups/snmp.conf</var></a> file configures the <code>snmp</code> backend. Add the following line to enable discovery using the <code>snmp</code> backend:</p>
 232
 233     <pre class="example">Address @LOCAL</pre>
 234
 235     <p>If you don't use "public" as your community name, change the <code>Community</code> line as well:</p>
 236
 237     <pre class="example">Community <I>your community name</I></pre>
 238
 239     <blockquote><b>Note:</b> The <code>snmp</code> backend will not be able to find any printers on your network if SNMP v1 or broadcasting are disabled on your network. Also, broadcasts are typically limited to the local subnet, so printers on different networks cannot be discovered using SNMP.</blockquote>
 240
 241     <h3>Troubleshooting SNMP Problems</h3>
 242
 243     <p>The <code>snmp</code> backend sometimes exposes problems in vendor implementations. If you are experiencing long delays in loading the CUPS web interface administration page, or if you don't see your printer listed, the following instructions will help you to diagnose those problems and/or provide important feedback to the CUPS developers so that we can correct problems and improve the <code>snmp</code> backend in future releases.</p>
 244
 245     <p>The SNMP backend supports a debugging mode that is activated by running it from a shell prompt. Run the following command to get a verbose log of the <code>snmp</code> backend:</p>
 246
 247     <pre class="command">CUPS_DEBUG_LEVEL=2 /usr/lib/cups/backend/snmp @LOCAL 2>&amp;1 | tee snmp.log</pre>
 248
 249     <p>On macOS you'll find the backend in /usr/libexec/cups/backend instead:</p>
 250
 251     <pre class="command">CUPS_DEBUG_LEVEL=2 /usr/libexec/cups/backend/snmp @LOCAL 2>&amp;1 | tee snmp.log</pre>
 252
 253     <p>The output will look something like this:</p>
 254
 255     <pre class="example"> 1  INFO: Using default SNMP Address @LOCAL
 256  2  INFO: Using default SNMP Community public
 257  3  DEBUG: Scanning for devices in "public" via "@LOCAL"...
 258  4  DEBUG: 0.000 Sending 46 bytes to 10.0.1.255...
 259  5  DEBUG: SEQUENCE 44 bytes
 260  6  DEBUG:     INTEGER 1 bytes 0
 261  7  DEBUG:     OCTET STRING 6 bytes "public"
 262  8  DEBUG:     Get-Request-PDU 31 bytes
 263  9  DEBUG:         INTEGER 4 bytes 1149539174
 264 10  DEBUG:         INTEGER 1 bytes 0
 265 11  DEBUG:         INTEGER 1 bytes 0
 266 12  DEBUG:         SEQUENCE 17 bytes
 267 13  DEBUG:             SEQUENCE 15 bytes
 268 14  DEBUG:                 OID 11 bytes .1.3.6.1.2.1.25.3.2.1.2.1
 269 15  DEBUG:                 NULL VALUE 0 bytes
 270 16  DEBUG: 0.001 Received 55 bytes from 10.0.1.42...
 271 17  DEBUG: community="public"
 272 18  DEBUG: request-id=1149539174
 273 19  DEBUG: error-status=0
 274 20  DEBUG: SEQUENCE 53 bytes
 275 21  DEBUG:     INTEGER 1 bytes 0
 276 22  DEBUG:     OCTET STRING 6 bytes "public"
 277 23  DEBUG:     Get-Response-PDU 40 bytes
 278 24  DEBUG:         INTEGER 4 bytes 1149539174
 279 25  DEBUG:         INTEGER 1 bytes 0
 280 26  DEBUG:         INTEGER 1 bytes 0
 281 27  DEBUG:         SEQUENCE 26 bytes
 282 28  DEBUG:             SEQUENCE 24 bytes
 283 29  DEBUG:                 OID 11 bytes .1.3.6.1.2.1.25.3.2.1.2.1
 284 30  DEBUG:                 OID 9 bytes .1.3.6.1.2.1.25.3.1.5
 285 31  DEBUG: add_cache(addr=0xbfffe170, addrname="10.0.1.42", uri="(null)", id="(null)", make_and_model="(null)")
 286 32  DEBUG: 0.002 Sending 46 bytes to 10.0.1.42...
 287 33  DEBUG: SEQUENCE 44 bytes
 288 34  DEBUG:     INTEGER 1 bytes 0
 289 35  DEBUG:     OCTET STRING 6 bytes "public"
 290 36  DEBUG:     Get-Request-PDU 31 bytes
 291 37  DEBUG:         INTEGER 4 bytes 1149539175
 292 38  DEBUG:         INTEGER 1 bytes 0
 293 39  DEBUG:         INTEGER 1 bytes 0
 294 40  DEBUG:         SEQUENCE 17 bytes
 295 41  DEBUG:             SEQUENCE 15 bytes
 296 42  DEBUG:                 OID 11 bytes .1.3.6.1.2.1.25.3.2.1.3.1
 297 43  DEBUG:                 NULL VALUE 0 bytes
 298 44  DEBUG: 0.003 Received 69 bytes from 10.0.1.42...
 299 45  DEBUG: community="public"
 300 46  DEBUG: request-id=1149539175
 301 47  DEBUG: error-status=0
 302 48  DEBUG: SEQUENCE 67 bytes
 303 49  DEBUG:     INTEGER 1 bytes 0
 304 50  DEBUG:     OCTET STRING 6 bytes "public"
 305 51  DEBUG:     Get-Response-PDU 54 bytes
 306 52  DEBUG:         INTEGER 4 bytes 1149539175
 307 53  DEBUG:         INTEGER 1 bytes 0
 308 54  DEBUG:         INTEGER 1 bytes 0
 309 55  DEBUG:         SEQUENCE 40 bytes
 310 56  DEBUG:             SEQUENCE 38 bytes
 311 57  DEBUG:                 OID 11 bytes .1.3.6.1.2.1.25.3.2.1.3.1
 312 58  DEBUG:                 OCTET STRING 23 bytes "HP LaserJet 4000 Series"
 313 59  DEBUG: 1.001 Probing 10.0.1.42...
 314 60  DEBUG: 1.001 Trying socket://10.0.1.42:9100...
 315 61  DEBUG: 10.0.1.42 supports AppSocket!
 316 62  DEBUG: 1.002 Scan complete!
 317 63  network socket://10.0.1.42 "HP LaserJet 4000 Series" "HP LaserJet 4000 Series 10.0.1.42" ""</pre>
 318
 319     <p>The first two lines are just informational and let you know that the default community name and address are being used. Lines 3-15 contain the initial SNMP query for the device type OID (.1.3.6.1.2.1.25.3.2.1.2.1) from the Host MIB.</p>
 320
 321     <p>Lines 16-31 show the response we got from an HP LaserJet 4000 network printer. At this point we discover that it is a printer device and then send another SNMP query (lines 32-43) for the device description OID (.1.3.6.1.2.1.25.3.2.1.3.1) from the Host MIB as well.</p>
 322
 323     <p>Lines 44-58 show the response to the device description query, which tells us that this is an HP LaserJet 4000 Series printer.</p>
 324
 325     <p>On line 59 we start our active connection probe and discover that this print server supports the AppSocket (JetDirect) protocol on port 9100.</p>
 326
 327     <p>Finally, line 63 shows the device information line for the print server that is sent to CUPS.</p>
 328
 329     <p>If you don't see your printer listed, or the wrong information is listed, then you need to gather more information on the printer. The easiest way to do this is to run the snmpwalk command:</p>
 330
 331     <pre class="command">snmpwalk -Cc -v 1 -c public ip-address | tee snmpwalk.log</pre>
 332
 333     <p>where "ip-address" is the IP address of the printer or print server. You should see a <em>lot</em> of values stream by - the ones you want to see are:</p>
 334
 335     <pre class="example">HOST-RESOURCES-MIB::hrDeviceType.1 = OID: HOST-RESOURCES-TYPES::hrDevicePrinter
 336 HOST-RESOURCES-MIB::hrDeviceDescr.1 = STRING: HP LaserJet 4000 Series</pre>
 337
 338     <p>The hrDeviceType line should show hrDevicePrinter; if not, then your printer or print server doesn't identify itself as a printer. The hrDeviceDescr line should provide a human-readable string for the make and model of the printer, although in some cases you'll just see something less useful like "Axis OfficeBASIC Parallel Print Server".</p>
 339
 340     <p>Once you have collected the snmpwalk output, you should go to the  <a href="https://github.com/apple/cups/issues">CUPS Issue Tracker</a> page to submit a feature request to support your printer or print server. Be sure to attach those two log files you created - they will help us to identify the SNMP values we need to look for.</p>
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