UUCP Permit-type Field

This field contains a keyword that denotes how to interpret the ID list. The following table lists the keywords and their meanings.

Table 36-9 Permit-type Field

UUCP ID-list Field

This field contains a list of login names or group names that are to be permitted or denied queuing to this job grade. The list of names are separated by a blank space and terminated by a newline character. The keyword Any is used to denote that anyone is permitted to queue to this job grade.

Other UUCP Configuration Files

This section describes three less-frequently modified files that impact the use of UUCP facilities.

UUCP /etc/uucp/Devconfig File

The /etc/uucp/Devconfig file enables you to configure devices by service--uucp or cu. Devconfig entries define the STREAMS modules that are used for a particular device. They have the following format:

service=x device=y push=z[:z...]

x can be cu, uucico, or both services separated by a colon. y is the name of a network and must match an entry in the Devices file. z is replaced by the names of STREAMS modules in the order that they are to be pushed onto the Stream. Different modules and devices can be defined for cu and uucp services.

The following entries are for a STARLAN network and would most commonly be used in the file:

service=cu       device=STARLAN     push=ntty:tirdwr 
service=uucico   device=STARLAN     push=ntty:tirdwr 

This example pushes ntty, then tirdwr.

UUCP /etc/uucp/Limits File

The /etc/uucp/Limits file controls the maximum number of simultaneous uucicos, uuxqts, and uuscheds that are running in the uucp networking. In most situations, the default values are acceptable and no changes are needed. If you want to change them, however, use any text editor.

The format of the Limits file is as follows:

service=x max=y:

x can be uucico, uuxqt or uusched, and y is the limit that is permitted for that service. The fields can be in any order and in lowercase.

The following entries should most commonly be used in the Limits file:

service=uucico max=5 
service=uuxqt max=5 
service=uusched max=2 

The example allows five uucicos, five uuxqts, and two uuscheds running on your machine.

UUCP remote.unknown File

The other file that affects the use of communication facilities is the remote.unknown file. This file is a binary program that executes when a machine that is not found in any of the Systems files starts a conversation. This program logs the conversation attempt and drops the connection.

Caution - If you change the permissions of the remote.unknown file so that it cannot execute, your system accepts connections from any system.

This program executes when a machine that is not in any of the Systems starts a conversation. The program logs the conversation attempt but fails to make a connection. If you change the permissions of this file so that it cannot execute (chmod 000 remote.unknown), your system accepts any conversation requests. This is not a trivial change, and you should have good reasons for making it.

UUCP Administrative Files

The UUCP administrative files are described next. These files are created in spool directories to lock devices, hold temporary data, or keep information about remote transfers or executions.

• Temporary data files (TM) - These data files are created by UUCP processes under the spool directory /var/spool/uucp/x when a file is received from another computer. The directory x has the same name as the remote computer that is sending the file. The names of the temporary data files have the following format:

  TM.pid.ddd

  pid is a process ID and ddd is a sequential three-digit number that starts at 0.

  When the entire file is received, the TM.pid.ddd file is moved to the path name that is specified in the C.sysnxxxx file (discussed subsequently) that caused the transmission. If processing is abnormally terminated, the TM.pid.ddd file can remain in the x directory. These files should be automatically removed by uucleanup.

• Lock files (LCK) - Lock files are created in the /var/spool/locks directory for each device in use. Lock files prevent duplicate conversations and multiple attempts to use the same calling device. The following table shows the different types of UUCP lock files.

Table 36-10 UUCP Lock Files

These files can remain in the spool directory if the communications link is unexpectedly dropped (usually on computer crashes). The lock file is ignored (removed) after the parent process is no longer active. The lock file contains the process ID of the process that created the lock.

• Work file (C.) - Work files are created in a spool directory when work (file transfers or remote command executions) has been queued for a remote computer. The names of work files have the following format:

  C.sysnxxxx

  sys is the name of the remote computer, n is the ASCII character that represents the grade (priority) of the work, and xxxx is the four-digit job sequence number that is assigned by UUCP. Work files contain the following information:

  • Full path name of the file to be sent or requested.

  • Full path name of the destination or user or file name.

  • User login name.

  • List of options.

  • Name of associated data files in the spool directory. If the uucp -C or uuto -p option was specified, a dummy name (D.0) is used.

  • Mode bits of the source file.

  • Remote user's login name to be notified on completion of the transfer.

• Data file(D.) - Data files are created when you specify on the command line to copy the source file to the spool directory. The names of data files have the following format:

  D.systmxxxxyyy - systm is the first five characters in the name of the remote computer, xxxx is a four-digit job sequence number assigned by uucp. The four-digit job sequence number can be followed by a subsequence number. yyy is used when several D. files are created for a work (C.) file.

• X. (execute file) - Execute files are created in the spool directory prior to remote command executions. The names of execute files have the following format:

  X.sysnxxxx

  sys is the name of the remote computer. n is the character that represents the grade (priority) of the work. xxxx is a four-digit sequence number that is assigned by UUCP. Execute files contain the following information:

  • Requester's login and computer name

  • Names of files that are required for execution

  • Input to be used as the standard input to the command string

  • Computer and file name to receive standard output from the command execution

  • Command string

  • Option lines for return status requests