11.3.3.1 Using the smitty mkpq Command

11.4 Troubleshooting Remote Printing Problems

Trying to find out why print jobs from a remote client get lost on the way to a server can be a frustrating problem. In this section, some common errors, as well as how to trace a job sent by a remote client using the iptrace facility, is discussed.

11.4.1 0781-374 Error Message

If you attempt to send a print job to a remote print server whose lpd daemon is down, you will receive the following message:

0781-374 Connection to server timed out after retrying
rembak:errno=79: A remote host refused an attempted connect operation

To correct this problem start the lpd daemon on the remote system using

startsrc -s lpd

11.4.2 0781-202 Error Message

If you have a queue, finprt or fin2, on a client system, sv1051c, and the host name for that client is not in the /etc/hosts.lpd or the /etc/hosts.equiv file then you will receive a 0781-202 error message when the lpstat command is run. See Figure 110 for an example of the command output. This problem is also seen with name server and routing problems.

# lpstat Queue Dev Status Job Files User PP % Blks Cp Rnk ------- ----- --------- --- ------------------ ---------- ---- -- ----- --- --- finprt @sv11 READY finprt: 0781-202 your host does not have line printer access. lpforu lp0 READY fin2 @sv11 READY fin2: 0781-202 your host does not have line printer access. #

Figure 110: 0781-202 Error Message

To correct this problem, you need to edit the /etc/hosts.lpd file on the server and enter the host name of the client system as in Figure 111.



Figure 111: Content of /etc/hosts.lpd

11.4.3 How to Run a Remote Trace

The question, "What is getting sent to the remote system when I print?" can be answered by using remote trace.

11.4.3.1 What an iptrace Can Tell You

The following list shows what an iptrace can tell you:

• Characters actually sent over the network, even binary control characters.

• Responses that come from the LPD.

• Content of the control file.

• Which side terminated the conversation.

• Status information being sent back by the LPD.

• If the entire file gets sent to the LPD.

• If the control files follow the RFC-1179 standard.

11.4.3.2 Using the iptrace Facility

The iptrace facility can easily show what is being sent to the remote system using the following command:

1. iptrace -p printer -a -b -s source_host -d dest_host /tmp/trace.out

Table 17 provides the iptrace command flags.


Table 17: Flags for the iptrace Command

1. Print the job to the remote queue using the following command:

   enq -Pqueue_name filename
   

   or use:

   lpstat -vqueue_name

2. Check to see if the file has grown using ls -l /tmp/trace.out.

   # ls -l /tmp/trace.out
   -rw-r--r--   1 root     system      4538 Nov 09 11:17 /tmp/trace.out
   

3. If it is still 11 bytes, then you have made an error in the command. Use the kill command and end the process, then start again. Get the job ID using the command:

   # ps -ef |grep ipt
   root 30984     1   0 11:17:47      -  0:00 iptrace -p printer -a -b -s sv1051c -d sv1166f /tmp/trace.out
   root 31234 26556   1 11:20:46 pts/10  0:00 grep ipt
   

4. Kill the trace command using the command:

   kill -9 job_id
   

5. Format the output into a text file:

   ipreport /tmp/trace.out > /tmp/report.out
   

The report contains three or four parts for each packet of data. These are:

• MAC header

• IP header

• TCP header

• b>data (If to/from application layer, that is, if FLAG=PUSH)

11.4.3.3 How to Interpret the Trace

The MAC header does not supply much information useful to debugging printing.

The IP header gives the direction of the data flow and the number of bytes in the packet, but direction is also given in the TCP packet.

The TCP packet gives the:

• Direction of packet source port.

• Handshaking and purpose of packet flags.

• Source port number. This is important because of the multi-tasking environment. Packets from a status can be interspersed with packets from a print job, but for a single job the source port will remain the same.

• Packet identification. Use th_seq and th_ack to make sure the packets are in order, and to see which packet an ACK is responding to.

• Window size th_win. The data packet shows the actual data that is sent back and forth.

The data packets contain queue names, command information, actual data to be printed, print flags, and error messages back from the remote system lpd. It often simplifies the reading of the data to extract the data from the other packets. This is usually quite easy to do because all data lines of importance begin with at least four zeros. However when you do this, you corrupt the information about who sent individual packets.

grep 0000 /tmp/report.out > /tmp/datasent.out

The size of this file will largely depend upon the size of the data file being printed. For this reason, start with a small file. A useful command is:

echo "AAAAA" | qprt -Pqueue_name

This will show in the grep output as:

...
00000000     41414141 410a                           |AAAAA.          |
...

You will notice that the data is divided into three columns. These are:

• Column 1, a character count, prior to the current line

• Column 2, the data in HEX

• Column 3, the data in ASCII, with periods for non-printable characters

A PostScript output might look something like this:

!data        hex equivalent of the characters         ASCII equiv. of
!byte in     sent to the remote host                  the characters.
!packet
00000000     020405ac                                |....            |
00000000     020405ac                                |....            |
00000000     0266696e 616c0a                         |.final.         |
00000000     00                                      |.               |
00000000     03313033 20646641 31303137 73763130     |.103 dfA1017sv10|
00000010     3531630a                                |51c.            |
00000000     00                                      |.               |
00000000     53746172 74207465 7374696e 670a5468     |Start testing.Th|
00000010     69732069 73206120 74657374 20707269     |is is a test pri|
00000020     6e74206a 6f622e0a 4920616d 20757369     |nt job..I am usi|
00000030     6e672069 70747261 63652074 6f207472     |ng iptrace to tr|
00000040     61636520 72656d6f 74652070 72696e74     |ace remote print|
00000050     206a6f62 732e0a46 696e6973 68207465     | jobs..Finish te|
00000060     7374696e 672e0a                         |sting..         |
00000000     00                                      |.               |
00000000     00                                      |.               |
00000000     02313038 20636641 31303137 73763130     |.108 cfA1017sv10|
00000010     3531630a                                |51c.            |
00000000     00                                      |.               |
00000000     48737631 30353163 0a50726f 6f740a66     |Hsv1051c.Proot.f|
00000010     64664131 30313773 76313035 31630a55     |dfA1017sv1051c.U|
00000020     64664131 30313773 76313035 31630a4e     |dfA1017sv1051c.N|
00000030     53544449 4e2e3237 3535300a 2d4e310a     |STDIN.27550.-N1.|
00000040     2d5a726f 6f744073 76313035 31630a2d     |-Zroot@sv1051c.-|
00000050     74726f6f 74407376 31303531 630a2d54     |troot@sv1051c.-T|
00000060     53544449 4e2e3237 3535300a              |STDIN.27550.    |
00000000     00                                      |.               |
00000000     00                                      |.               |
...

The information gained from this output includes:

• The remote queue name is final.

• The data file contains 103 bytes.

• The job number is 1017.

• The local host name is sv1051c.

Some of the things to look for in the output are:

There is always an initial handshake protocol that seems to look like:

00000000     020405ac                                |....
00000000     020405ac                                |....

The middle column always starts with 02 for the handshake part. The rest is identification information and doesn't matter in this discussion.

In general, lines like the following indicate a positive acknowledgment:

00000000     00                                      |.               |

One of the first lines in the file is the queue name:

00000000     0266696e 616c0a                         |.final.         |

Notice in the middle column that this begins with 02. This is a flag to indicate that this is the start of a print request. The name on the end of the line is the queue name.

Command Identifiers for LPD defined in RFC

A status request for a queue would start with an 03.The following binary identifiers are defined in the rfc.

01

Print any waiting jobs. Not supported by AIX rembak.

02

Receive a printer job. Standard command for printing.

03

Send queue state (short). Default status with qchk, lpstat, enq -A.

04

Send queue state (long).

05

Remove jobs.

A short distance down the file a line will contain the temporary file name:

00000000     03313033 20646641 31303137 73763130     |.103 dfA1017sv10|
00000010     3531630a                                |51c.            |

In this case it begins with 03 in the middle column for data file. This is a subcommand of the receive a printer job command.

The receive printer job subcommands are as follows:

01

Abort job.

02

Receive control file.

| 02 | Count | SP | Name | LF |

03

Receive data file.

| 03 | Count | SP | Name | LF |

The preceding example line shows a receive data file subcommand with the following information:

• The 103 in the 3rd column indicates the number of bytes in the file.

• The file name starts with df for data file.

• The job number is the next part of the data file, in this example it is 1017.

• The last part of the file name is the sending host name sv1051c.

The next packet of data from the client to the server is the data file itself. Check this file for extraneous characters, line feeds, spaces, tabs, and other things that might affect the format. The data in the right-hand column should be exactly what was on the client. As shown in the following example:

00000000     53746172 74207465 7374696e 670a5468     |Start testing.Th|
00000010     69732069 73206120 74657374 20707269     |is is a test pri|
00000020     6e74206a 6f622e0a 4920616d 20757369     |nt job..I am usi|
00000030     6e672069 70747261 63652074 6f207472     |ng iptrace to tr|
00000040     61636520 72656d6f 74652070 72696e74     |ace remote print|
00000050     206a6f62 732e0a46 696e6973 68207465     | jobs..Finish te|
00000060     7374696e 672e0a                         |sting..         |

The next packet from the client is usually the control file name, as shown in the following example:

00000000     02313038 20636641 31303137 73763130     |.108 cfA1017sv10|
00000010     3531630a                                |51c.            |

The subcommand for control file begins with 02 in the middle column. The information from the receive control file is:

• 02 is a control-file descriptor.

• There is 108 bytes of control file information.

• The control file name starts with cfA.

• The job number 1017 was from host sv1051c.

A sample control file excerpt follows:

00000000     48737631 30353163 0a50726f 6f740a66     |Hsv1051c.Proot.f|
00000010     64664131 30313773 76313035 31630a55     |dfA1017sv1051c.U|
00000020     64664131 30313773 76313035 31630a4e     |dfA1017sv1051c.N|
00000030     53544449 4e2e3237 3535300a 2d4e310a     |STDIN.27550.-N1.|
00000040     2d5a726f 6f744073 76313035 31630a2d     |-Zroot@sv1051c.-|
00000050     74726f6f 74407376 31303531 630a2d54     |troot@sv1051c.-T|
00000060     53544449 4e2e3237 3535300a              |STDIN.27550.    |

The meaning of the control file format is shown in Table 18.


Table 18: Control File Format

11.5 Filters