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.\"	@(#)implement.ms	4.1 (Berkeley) %G%
.\"
.RP
.TM 78-1273-5 39199 39199-11
.ND October 31, 1978
.if \n(TN>0 .FS
.if \n(TN>0 * On internship from Department 9444.
.if \n(TN>0 .FE
.TL
Uucp Implementation Description
.AU "MH 2C-572" 3126
.ie \n(TN>0 D. A. Nowitz\s-2\u*\d\s+2
.el D. A. Nowitz
.AB
.PP
Uucp is a series of programs designed to permit communication
between
UNIX
systems using either dial-up or hardwired communication
lines.
This document gives a detailed implementation
description of the current (second)
implementation of uucp.
.PP
This document is
for use by an administrator/installer of the system.
It is not meant as a user's guide.
.AE
.CS 12 5 15
.SH
Introduction
.LP
Uucp is a series of programs designed to permit communication between
.UX
systems using either dial-up or
hardwired communication lines.
It is used for file transfers and remote command execution.
The first version of the system was designed and implemented
by M. E. Lesk.\s-2\u1\d\s+2
.FS
1 M. E. Lesk and A. S. Cohen,
.UX
Software Distribution by Communication Link,
.ie \n(TN>0 TM-77-1274-3, TM-77-8234-5.
.el private communication.
.FE
This paper describes the current (second) implementation
of the system.
.LP
Uucp is a batch type operation.
Files are created in a spool directory for processing
by the uucp demons.
There are three types of files used for the execution
of work.
.I Data\ files
contain data for transfer to remote systems.
.I Work\ files
contain directions for file transfers between systems.
.I Execution\ files
are directions for
.UX
command executions which
involve the resources of one or more systems.
.LP
The uucp system consists of four primary and two
secondary programs.
The primary programs are:
.RS
.IP uucp 10
This program creates work and gathers data files in the spool directory
for the transmission of files.
.IP uux
This program creates work files, execute files and gathers data files for the remote execution of
.UX
commands.
.IP uucico
This program executes the work files for data transmission.
.IP uuxqt
This program executes the execution files for
.UX
command execution.
.RE
.ne 10
.LP
The secondary programs are:
.RS
.IP uulog 10
This program updates the log file with new entries
and reports on the status of uucp requests.
.IP uuclean
This program removes old files from the spool directory.
.LP
.RE
The remainder of this paper will describe the operation
of each program, the installation of the system,
the security aspects of the system,
the files required for execution,
and the administration of the system.
.NH
Uucp - UNIX to UNIX File Copy
.LP
The
.I uucp
command is the user's primary interface with the system.
The
.I uucp
command was designed to look like
.I cp
to the user.
The syntax is
.IP
.I uucp\ \ 
.B [
option
.B ]
\ ...\ \ source\ ...\ \ destination
.LP
where the source and destination
may contain the prefix
.I system-name!
which indicates the system on which the file
or files reside
or where they will be copied.
.LP
The options interpreted by
.I uucp
are:
.RS
.IP \-d 10
Make directories when necessary for copying the file.
.IP \-c
Don't copy source files to the spool directory,
but use the specified source when the actual
transfer takes place.
.IP \-g\fIletter\fR
Put
.I letter
in as the grade in the name of the work file.
(This can be used to change the order of work for a particular
machine.)
.IP \-m
Send mail on completion of the work.
.LP
The following options are used primarily for debugging:
.IP \-r 10
Queue the job but do not start
.I uucico
program.
.IP \-s\fIdir\fR
Use directory
.I dir
for the spool directory.
.IP \-x\fInum\fR
.I Num
is the level of debugging output desired.
.RE
.LP
The destination may be a directory name,
in which case the file name is taken from the last part of the
source's name.
The source
name may contain special shell characters
such as ``\fI?*[]\fR''.
If a source argument has a
.I system-name!
prefix for a remote system,
the file name expansion will be done on the remote system.
.LP
The command
.IP "" 12
uucp\ \ *.c\ \ usg!/usr/dan
.LP
will set up the transfer of all files whose names end with ``.c''
to the ``/usr/dan'' directory on the``usg'' machine.
.LP
The source and/or destination names may also contain a
.I ~user
prefix.
This translates to the login directory on
the specified system.
For names with partial path-names,
the current directory is prepended to the file name.
File names with
.I ../
are not permitted.
.LP
The command
.IP "" 12
uucp\ \ usg!~dan/*.h\ \ ~dan
.LP
will set up the transfer of files whose names end with ``.h''
in dan's login
directory on system ``usg'' to dan's local
login directory.
.LP
For each source file,
the program will check the source and destination
file-names
and the system-part of each to
classify the work into one of five types:
.RS
.IP [1]
Copy source to destination on local system.
.IP [2]
Receive files from other systems.
.IP [3]
Send files to a remote systems.
.IP [4]
Send files from remote systems
to another remote system.
.IP [5]
Receive files from remote systems when the source
contains special shell characters as
mentioned above.
.RE
.LP
After the work has been set up in the spool directory,
the
.I uucico
program is started to try to contact the other
machine to execute the work (unless the \-r option
was specified).
.SH
Type 1
.LP
A
.I cp
command is used to do the work.
The
.I \-d
and the
.I \-m
options are not honored in this case.
.SH
Type 2
.LP
A one line
.I "work file"
is created for each file requested and put in the spool directory
with the following fields, each separated by a blank.
(All
.I "work files"
and
.I "execute files"
use a blank as the field separator.)
.RS
.IP [1]
R
.IP [2]
The full path-name of the source or a ~user/path-name.
The
.I ~user
part will be expanded on the remote system.
.IP [3]
The full path-name of the destination file.
If the
.I ~user
notation is used, it will be immediately
expanded to be the login directory for the user.
.IP [4]
The user's login name.
.IP [5]
A ``\-'' followed by an option list.
(Only the \-m and \-d options will appear in this list.)
.RE
.KS
.SH
Type 3
.LP
For each source file, a
.I "work file"
is created and the source file is copied into a
.I "data file"
in the spool directory.
(A ``\-c'' option on the
.I uucp
command will prevent the
.I "data file"
from being made.)
In this case, the file will be transmitted from
the indicated source.)
The fields of each entry are given below.
.RS
.IP [1]
S
.IP [2]
The full-path name of the source file.
.IP [3]
The full-path name of the destination or
~user/file-name.
.IP [4]
The user's login name.
.IP [5]
A ``\-'' followed by an option list.
.IP [6]
The name of the
.I "data file"
in the spool directory.
.IP [7]
The file mode bits of the source file
in octal print format
(e.g. 0666).
.RE
.KE
.SH
Type 4 and Type 5
.LP
.I Uucp
generates a
.I uucp
command and sends it to the remote machine;
the remote
.I uucico
executes the
.I uucp
command.
.NH
Uux - UNIX To UNIX Execution
.LP
The
.I uux
command is used to set up the execution of a
.UX
command
where the execution machine and/or some of the
files are remote.
The syntax of the uux command is
.IP
.I uux\ \ 
.B [
\-
.B "] ["
option
.B ]
\ ...\ \ command-string
.LP
where the command-string is made up of one or more arguments.
All special shell characters such as ``<>|^'' must be quoted
either by quoting the entire command-string
or quoting the character as a separate argument.
Within the command-string, the command and file names may
contain a
.I system-name!
prefix.
All arguments which do not contain a ``!'' will not
be treated as files.
(They will not be copied to the execution machine.)
The ``\-'' is used to indicate that the standard input
for
.I command-string
should be inherited from the standard input
of the
.I uux
command.
The options, essentially for debugging, are:
.RS
.IP \-r 10
Don't start
.I uucico
or
.I uuxqt
after queuing the job;
.IP \-x\fInum\fR
Num is the level of debugging output desired.
.RE
.LP
The command
.IP "" 12
pr\ \ abc\ \ |\ \ uux\ \ \-\ \ usg!lpr
.LP
will set up the output of ``pr abc''
as standard input to an lpr command
to be executed on system ``usg''.
.LP
.I Uux
generates an
.I "execute file"
which contains the
names of the files required
for execution (including standard input),
the user's login name, the destination
of the standard output, and the command to be executed.
This file is either put in the spool directory
for local execution or sent to the remote system using
a generated send command (type 3 above).
.LP
For required files which are not on the execution machine,
.I uux
will generate receive command files (type 2 above).
These command-files will be put on the execution machine and
executed by the
.I uucico
program.
(This will work only if the local system has permission
to put files in the remote spool directory as controlled
by the remote
.I USERFILE .
)
.LP
The
.I "execute file"
will be processed
by the
.I uuxqt
program on the execution machine.
It is made up of several lines,
each of which contains an identification character
and one or more arguments.
The order of the lines in the file is not relevant
and some of the lines may not be present.
Each line is described below.
.RS
.SH
User Line
.IP
U\ \ user\ \ system
.LP
where the
.I user
and
.I system
are the requester's login name and system.
.SH
Required File Line
.IP
F file-name real-name
.LP
where the
.I file-name
is the generated name of a file for the execute machine
and
.I real-name
is the last part of the actual file name (contains no
path information).
Zero or more of these lines may be present in the
.I "execute file" .
The
.I uuxqt
program will check for the existence of all required
files before the command is executed.
.SH
Standard Input Line
.IP
I\ \ file-name
.LP
The standard input is either specified by a ``<'' in the
command-string or inherited from the standard input of the
.I uux
command if the ``\-'' option is used.
If a standard input is not specified,
``/dev/null'' is used.
.SH
Standard Output Line
.IP
O\ \ file-name\ \ system-name
.LP
The standard output is specified by a ``>'' within the
command-string.
If a standard output is not specified,
``/dev/null'' is used.
(Note \- the use of ``>>'' is not implemented.)
.SH
Command Line
.IP
C\ \ command\ \ 
.B [
arguments
.B ]
\ ...
.LP
The arguments are those specified in the command-string.
The standard input and standard output will not appear on this
line.
All
.I "required files"
will be moved to the execution directory (a subdirectory
of the spool directory)
and the
.UX
command is executed using the Shell specified in the
.I uucp.h
header file.
In addition, a shell ``PATH'' statement is prepended
to the command line as specified in the
.I uuxqt
program.
.LP
After execution, the standard output is copied or set up to be
sent to the proper place.
.RE
.NH
Uucico - Copy In, Copy Out
.LP
The
.I uucico
program will perform the following major functions:
.RS
.IP -\ \  3
Scan the spool directory for work.
.IP -\ \  
Place a call to a remote system.
.IP -\ \ 
Negotiate a line protocol to be used.
.IP -\ \ 
Execute all requests from both systems.
.IP -\ \ 
Log work requests and work completions.
.RE
.LP
.I Uucico
may be started in several ways;
.RS
.IP a) 5
by a system daemon,
.IP b)
by one of the
.I
uucp, uux, uuxqt
.R
or
.I uucico
programs,
.IP c)
directly by the user (this is usually for testing),
.IP d)
by a remote system.
(The uucico program should be specified as the ``shell''
field in the ``/etc/passwd'' file for the ``uucp'' logins.)
.RE
.LP
When started by method a, b or c, the program is considered to
be in
.I MASTER
mode.
In this mode, a connection will be made to a remote system.
If started by a remote system (method d),
the program is considered to be in
.I SLAVE
mode.
.LP
The
.I MASTER
mode will operate in one of two ways.
If no system name is specified
(\-s option not specified)
the program will scan the spool directory for
systems to call.
If a system name is specified, that system will be called,
and work will only be done for that system.
.LP
The
.I uucico
program is generally started by another program.
There are several options used for execution:
.RS
.IP \-r1 10
Start the program in
.I MASTER
mode.
This is used when
.I uucico
is started by a program or ``cron'' shell.
.IP \-s\fIsys\fR
Do work only for system
.I sys.
If
.I \-s
is specified,
a call to the specified system
will be made even if there is no work for system
.I sys
in the spool directory.
This is useful for polling systems which do not have
the hardware to initiate a connection.
.LP
The following options are used primarily for debugging:
.IP \-d\fIdir\fR
Use directory
.I dir
for the spool directory.
.IP \-x\fInum\fR
.I Num
is the level of debugging output desired.
.RE
.LP
The next part of this section will describe the major steps within
the
.I uucico
program.
.SH
Scan For Work
.LP
The names of the work related files in the spool directory have format
.IP
type . system-name grade number
.LP
where:
.IP
.I Type
is an upper case letter,
(
.I C
-\ copy command file,
.I D
-\ data file,
.I X
-\ execute file);
.IP
.I System-name
is the remote system;
.IP
.I Grade
is a character;
.IP
.I Number
is a four digit, padded sequence number.
.LP
The file
.IP "" 12
C.res45n0031
.LP
would be a
.I "work file"
for a file transfer between the local
machine and the ``res45'' machine.
.LP
The scan for work is done by looking through the
spool directory for
.I "work files"
(files with prefix ``C.'').
A list is made of all systems to be called.
.I Uucico
will then call each system and process all
.I "work files" .
.SH
Call Remote System
.LP
The call is made using information from several
files which reside in the uucp program directory.
At the start of the call process, a lock is
set to forbid multiple conversations 
between the same two systems.
.LP
The system name is found in the
.I L.sys
file.
The information contained for each system is;
.RS
.IP [1]
system name,
.IP [2]
times to call the system
(days-of-week and times-of-day),
.IP [3]
device or device type to be used for call,
.IP [4]
line speed,
.IP [5]
phone number if field [3] is
.I ACU
or the device name (same as field [3])
if not
.I ACU,
.IP [6]
login information (multiple fields),
.RE
.LP
The time field is checked against the present time to see
if the call should be made.
.LP
The
.I
phone number
.R
may contain abbreviations (e.g. mh, py, boston) which get translated into dial
sequences using the
.I L-dialcodes
file.
.LP
The
.I L-devices
file is scanned using fields [3] and [4] from the
.I L.sys
file to find an available device for the call.
The program will try all devices which satisfy
[3] and [4] until the call is made, or no more
devices can be tried.
If a device is successfully opened, a lock file
is created so that another copy of
.I uucico
will not try to use it.
If the call is complete, the
.I
login information
.R
(field [6] of
.I L.sys )
is used to login.
.LP
The conversation between the two
.I uucico
programs begins with a handshake started by the called,
.I SLAVE ,
system.
The
.I SLAVE
sends a message to let the
.I MASTER
know it is ready to receive the system
identification and conversation sequence number.
The response from the
.I MASTER
is
verified by the
.I SLAVE
and if acceptable, protocol selection begins.
The
.I SLAVE
can also reply with a ``call-back required''
message in which case, the current conversation
is terminated.
.SH
Line Protocol Selection
.LP
The remote system sends a message
.IP "" 12
P\fIproto-list\fR
.LP
where proto-list is a string of characters, each
representing a line protocol.
.LP
The calling program checks the proto-list
for a letter corresponding to an available line
protocol and returns a
.I use-protocol
message.
The
.I use-protocol
message is
.IP "" 12
U\fIcode\fR
.LP
where code is either a one character
protocol letter or
.I N
which means there is no common protocol.
.SH
Work Processing
.LP
The initial roles (
.I MASTER
or
.I SLAVE
) for the work processing are
the mode in which each program starts.
(The 
.I MASTER
has been specified by the ``\-r1'' uucico option.)
The
.I MASTER
program does a work search similar to the
one used in the ``Scan For Work'' section.
.LP
There are five messages used during the
work processing, each specified by the first
character of the message.
They are;
.IP "" 12
.RS
.IP S 3
send a file,
.IP R
receive a file,
.IP C
copy complete,
.IP X
execute a
.I uucp
command,
.IP H
hangup.
.RE
.LP
The
.I MASTER
will send
.I R ,
.I S
or
.I X
messages until all work from the spool directory is
complete, at which point an
.I H
message will be sent.
The
.I SLAVE
will reply with
\fISY\fR, \fISN\fR, \fIRY\fR, \fIRN\fR, \fIHY\fR, \fIHN\fR,
\fIXY\fR, \fIXN\fr,
corresponding to
.I yes
or
.I no
for each request.
.LP
The send and receive replies are
based on permission to access the
requested file/directory using the
.I USERFILE
and read/write permissions of the file/directory.
After each file is copied into the spool directory
of the receiving system,
a copy-complete message is sent by the receiver of the file.
The message
.I CY
will be sent if the
file has successfully been moved from the
temporary spool file to the actual destination.
Otherwise, a
.I CN
message is sent.
(In the case of
.I CN ,
the transferred file will be in the spool
directory with a name beginning with ``TM'.)
The requests and results are logged on both systems.
.LP
The hangup response is determined by the
.I SLAVE
program by a work scan of the spool directory.
If work for the remote system exists in the
.I SLAVE's
spool directory, an
.I HN
message is sent and the programs switch roles.
If no work exists, an
.I HY
response is sent.
.SH
Conversation Termination
.LP
When a
.I HY
message is received by the
.I MASTER
it is echoed back to the
.I SLAVE
and the protocols are turned off.
Each program sends a final ``OO'' message to the
other.
The original
.I SLAVE
program will clean up and terminate.
The
.I MASTER
will proceed to call other systems
and process work as long as possible
or terminate if a
.I \-s
option was specified.
.LP
.NH
Uuxqt - Uucp Command Execution
.LP
The
.I uuxqt
program is used to execute
.I
execute files
.R
generated by
.I uux.
The
.I uuxqt
program may be started by either the
.I uucico
or
.I uux
programs.
The program scans the spool directory for
.I
execute files
.R
(prefix ``X.'').
Each one is checked to see if all the required files are available and
if so, the command line or send line is executed.
.LP
The
.I
execute file
.R
is described in the ``Uux''
section above.
.SH
Command Execution
.LP
The execution is accomplished by executing a
.I
sh \-c
.R
of the command line after appropriate
standard input and standard output have been opened.
If a standard output is specified, the program
will create a send command or copy the output
file as appropriate.
.NH
Uulog - Uucp Log Inquiry
.LP
The
.I uucp
programs create individual
log files for each program invocation.
Periodically,
.I uulog
may be executed to prepend these files to the
system logfile.
This method of logging was chosen to minimize file
locking of the logfile during program execution.
.LP
The
.I uulog
program merges the individual
log files and outputs specified log entries.
The output request is specified by the use of the
following options:
.RS
.IP \-s\fIsys\fR 9
Print entries where
.I sys
is the remote system name;
.IP \-u\fIuser\fR
Print entries for user
.I user.
.RE
.LP
The intersection of lines satisfying the two options is output.
A null
.I sys
or
.I user
means all system names or users respectively.
.NH
Uuclean - Uucp Spool Directory Cleanup
.LP
This program is typically started by the daemon, once a day.
Its function is to remove files from the spool directory which
are more than 3 days old.
These are usually files for work which can not be completed.
.LP
.LP
The options available are:
.RS
.IP \-d\fIdir\fR 10
The directory to be scanned is
.I dir .
.IP \-m
Send mail to the owner of each file being removed.
(Note that most files put into the spool directory
will be owned by the owner of the
uucp programs since the setuid bit will be set on these
programs.
The mail will therefore most often go to the owner
of the uucp programs.)
.IP \-n\fIhours\fR
Change the aging time from 72 hours to
.I hours
hours.
.IP \-p\fIpre\fR
Examine files with prefix
.I pre
for deletion.
(Up to 10 file prefixes may be specified.)
.IP \-x\fInum\fR
This is the level of debugging output desired.
.RE
.NH
Security
.LP
.LG
\fB
The uucp system, left unrestricted,
will let any outside user execute any commands
and copy in/out any file which is readable/writable
by the uucp login user.
It is up to the individual sites to be aware of this and
apply the protections that they feel are necessary.
\fR
.NL
.LP
There are several security features available aside from the
normal file mode protections.
These must be set up by the installer of the
.I uucp
system.
.IP - 3
The login for uucp does not get a standard shell.
Instead, the
.I uucico
program is started.
Therefore, the only work that can be done is through
.I uucico .
.IP -
A path check is done on file names that are to be sent
or received.
The
.I USERFILE
supplies the information for these checks.
The
.I USERFILE
can also be set up to require call-back
for certain login-ids.
(See the ``Files required for execution'' section
for the file description.)
.IP -
A conversation sequence count can be set up so
that the called system
can be more confident that the caller
is who he says he is.
.IP -
The
.I uuxqt
program comes with a list of commands that it
will execute.
A ``PATH'' shell statement is prepended to the command
line as specifed in the
.I uuxqt
program.
The installer may modify the list or remove the
restrictions as desired.
.IP -
The
.I L.sys
file should be owned by uucp and have mode 0400
to protect the phone numbers and login information
for remote sites.
(Programs uucp, uucico, uux, uuxqt should be also
owned by uucp and have the setuid bit set.)
.NH
Uucp Installation
.LP
There are several source modifications that may be required
before the system programs are compiled.
These relate to the directories used during compilation,
the directories used during execution,
and the local
.I
uucp system-name.
.R
.LP
The four directories are:
.RS
.IP lib 12
(/usr/src/cmd/uucp)
This directory contains the source files for generating the
.I uucp
system.
.IP program
(/usr/lib/uucp)
This is the directory used for the executable system programs and
the system files.
.IP spool
(/usr/spool/uucp)
This is the spool directory used during
.I uucp
execution.
.IP xqtdir
(/usr/spool/uucp/.XQTDIR)
This directory is used during execution of
.I "execute files" .
.RE
.LP
The names given in parentheses above are the default values
for the directories.
The italicized named
.I
lib, program, xqtdir,
.R
and
.I spool
will be used in the following text to represent the
appropriate directory names.
.LP
There are two files which may require modification,
the
.I makefile
file and the
.I uucp.h
file.
The following paragraphs describe the modifications.
The modes of
.I spool
and
.I xqtdir
should be made ``0777''.
.SH
Uucp.h modification
.LP
Change the
.I program
and the
.I spool
names from the default values to the directory
names to be used on the local system using
global edit commands.
.LP
Change the
.I define
value for
.I MYNAME
to be the local
.I uucp
system-name.
.SH
makefile modification
.LP
There are several
.I make
variable definitions which may need modification.
.RS
.IP INSDIR 10
This is the
.I program
directory
(e.g. INSDIR=/usr/lib/uucp).
This parameter is used if ``make cp'' is
used after the programs are compiled.
.IP IOCTL
This is required to be set if an appropriate
.I ioctl
interface subroutine does not exist in the standard
``C'' library;
the statement
``IOCTL=ioctl.o'' is required in this case.
.IP PKON
The statement ``PKON=pkon.o'' is required if the
packet driver is not in the kernel.
.RE
.SH
Compile the system
The command
.IP "" 12
make
.LP
will compile the entire system.
The command
.IP "" 12
make cp
.LP
will copy the commands to the
to the appropriate directories.
.LP
The programs
.I uucp ,
.I uux ,
and
.I uulog
should be put in ``/usr/bin''.
The programs
.I uuxqt ,
.I uucico ,
and
.I uuclean
should be put in the
.I program
directory.
.SH
Files required for execution
.LP
There are four files which are required for execution,
all of which should reside in the
.I program
directory.
The field separator for all files is a space unless otherwise
specified.
.SH
L-devices
.LP
This file contains entries for the call-unit devices and
hardwired connections which are to be used by
.I uucp.
The special device files are assumed to be in the
.I /dev
directory.
The format for each entry is
.IP "" 12
line\ \ call-unit\ \ speed
.LP
where;
.RS
.IP line 12
is the device for the line (e.g. cul0),
.IP call-unit
is the automatic call unit associated with
.I line
(e.g. cua0),
(Hardwired lines have a number ``0'' in this field.),
.IP speed
is the line speed.
.RE
.LP
The line
.IP "" 12
cul0\ \ cua0\ \ 300
.LP
would be set up for a system which
had device cul0 wired to a call-unit
cua0 for use at 300 baud.
.SH
L-dialcodes
.LP
This file contains entries with location abbreviations used
in the
.I L.sys
file (e.g. py, mh, boston).
The entry format is
.IP "" 12
abb\ \ dial-seq
.LP
where;
.RS
.IP abb 12
is the abbreviation,
.IP dial-seq
is the dial sequence to call that location.
.RE
.LP
The line
.IP "" 12
py\ \ 165\-
.LP
would be set up so that entry py7777 would
send 165\-7777 to the dial-unit.
.SH
LOGIN/SYSTEM NAMES
.LP
It is assumed that the
.I "login name"
used by a remote computer to call into a local computer
is not the same as the login name of a normal user
of that local machine.
However, several remote computers may employ the same
login name.
.LP
Each computer is given a unique
.I "system name"
which is transmitted at the start of each call.
This name identifies the calling machine to the called machine.
.SH
USERFILE
.LP
This file contains user accessibility information.
It specifies four types of constraint;
.RS
.IP [1]
which files can be accessed by a normal user of the local machine,
.IP [2]
which files can be accessed from a remote computer,
.IP [3]
which login name is used by a particular remote computer,
.IP [4]
whether a remote computer should be called back in order to confirm
its identity.
.RE
.LP
Each line in the file has the following format
.IP "" 6
login,sys\ \ 
.B [
c
.B ]
\ \ path-name\ \ 
.B [
path-name
.B ]
\ ...
.LP
where;
.RS
.IP login 12
is the login name for a user or the remote computer,
.IP  sys
is the system name for a remote computer,
.IP c
is the optional
.I
call-back required
.R
flag,
.IP path-name
is a path-name prefix that is acceptable for
.I user.
.LP
.RE
.LP
The constraints are implemented as follows.
.RS
.IP [1]
When the program is obeying a command stored on the local machine,
.I MASTER
mode,
the path-names allowed are those given for the first line in the
.I USERFILE
that has a login name that matches the login name of the user
who entered the command.
If no such line is found, the first line with a
.I null
login name is used.
.IP [2]
When the program is responding to a command from a remote machine,
.I SLAVE
mode, the path-names allowed are those given for the first line
in the file that has the system name that matches the system name
of the remote machine.
If no such line is found, the first one with a
.I null
system name is used.
.IP [3]
When a remote computer logs in, the login name that
it uses must appear in the
.I USERFILE .
There may be several lines with the same login name but one of them must
either have the name of the remote system or must contain a
.I null
system name.
.IP [4]
If the line matched in ([3]) contains a ``c'',
the remote machine is called back before any transactions take place.
.RE
.LP
The line
.IP "" 12
u,m  /usr/xyz
.LP
allows machine
.I m
to login with name
.I u
and request the transfer of files whose names start with
``/usr/xyz''.
.LP
The line
.IP "" 12
dan,  /usr/dan
.LP
allows the ordinary user
.I dan
to issue commands for files whose name starts with
``/usr/dan''.
.LP
The lines
.IP "" 12
u,m /usr/xyz  /usr/spool
.br
u,  /usr/spool
.LP
allows any remote machine to login with name
.I u ,
but if its system name is not
.I m ,
it can only ask to transfer files whose names start with
``/usr/spool''.
.LP
The lines
.IP "" 12
root,  /
.br
,   /usr
.LP
allows any user to transfer files beginning with ``/usr''
but the user with login
.I root
can transfer any file.
.SH
L.sys
.LP
Each entry in this file represents one system
which can be called by the local uucp programs.
The fields are described below.
.RS
.SH
system name
.LP
The name of the remote system.
.SH
time
.LP
This is a string which indicates the days-of-week
and times-of-day when the system should
be called
(e.g. MoTuTh0800\-1730).
.LP
The day portion may be a list containing
some of
.IP
.I
Su Mo Tu We Th Fr Sa
.R
.LP
or it may be
.I Wk
for any week-day or
.I Any
for any day.
.LP
The time should be a range of times (e.g. 0800\-1230).
If no time portion is specified, any time
of day is assumed to be ok for the call.
.SH
device
.LP
This is either
.I ACU
or the hardwired device to be used for the call.
For the hardwired case, the last part of the
special file name is used (e.g. tty0).
.SH
speed
.LP
This is the line speed for the call (e.g. 300).
.SH
phone
.LP
The phone number is made up of an optional
alphabetic abbreviation and a numeric part.
The abbreviation is one which appears in the
.I L-dialcodes
file (e.g. mh5900, boston995\-9980).
.LP
For the hardwired devices, this field contains
the same string as used for the
.I device
field.
.SH
login
.LP
The login information is given as a series of
fields and subfields in the format
.IP
expect\ \ send\ 
.B [
expect\ \ send
.B ]
\ ...
.LP
where;
.I expect
is the string expected to be read and
.I send
is the string to be sent when the
.I expect
string is received.
.LP
The expect field may be made up of subfields
of the form
.IP
expect\fB[\fR\-send\-expect\fB]\fR...
.LP
where the
.I send
is sent if the prior
.I expect
is not successfully read
and the
.I expect
following the
.I send
is the next expected string.
.LP
There are two special names available to be sent
during the login sequence.
The string
.I EOT
will send an EOT character and the string
.I BREAK
will try to send a BREAK character.
(The
.I BREAK
character is simulated using line speed changes
and null characters and may not work on all
devices and/or systems.)
.RE
.LP
A typical entry in the L.sys file would be
.IP "" 6
sys Any ACU 300  mh7654 login uucp ssword: word
.LP
The expect algorithm looks at the last part of the
string as illustrated in the password field.
.RE
.NH
Administration
.LP
This section indicates some events and files which must be
administered for the
.I uucp
system.
Some administration can be accomplished by 
.I "shell files"
which can be initiated by
.I crontab
entries.
Others will require manual intervention.
Some sample 
.I "shell files"
are given toward the end of this section.
.SH
SQFILE \- sequence check file
.LP
This file is set up in the
.I program
directory and contains an entry for each remote
system with which you agree to perform conversation
sequence checks.
The initial entry is just the system name of
the remote system.
The first conversation will add two items to the line,
the conversation count, and the date/time of the most
resent conversation.
These items will be updated with each conversation.
If a sequence check fails, the entry will have to
be adjusted.
.SH
TM \- temporary data files
.LP
These files are created in the
.I spool
directory while files are being copied
from a remote machine.
Their names have the form
.IP "" 12
\fBTM\fR.pid.ddd
.LP
where
.I pid
is a process-id and
.I ddd
is a sequential three digit number starting at zero
for each invocation of
.I uucico
and incremented for each file received.

After the entire remote file is received, the
.I TM
file is moved/copied to the requested destination.
If processing is abnormally terminated or the
move/copy fails, the file will remain in the
spool directory.
.LP
The leftover files should be periodically removed;
the
.I uuclean
program is useful in this regard.
The command
.IP "" 12
uuclean\ \ \-pTM
.LP
will remove all
.I TM
files older than three days.
.SH
LOG \- log entry files
.LP
During execution of programs, individual
.I LOG
files are created in the
.I spool
directory with information about
queued requests, calls to remote systems,
execution of
.I uux
commands and file copy results.
These files should be combined into the
.I LOGFILE
by using the
.I uulog
program.
This program will put the new
.I LOG
files at the beginning of the existing
.I LOGFILE.
The command
.IP "" 12
uulog
.LP
will accomplish the merge.
Options are available to print some or all the
log entries after the files are merged.
The
.I LOGFILE
should be removed periodically
since it is copied each time new LOG
entries are put into the file.
.LP
The
.I LOG
files are created initially with mode 0222.
If the program which creates the file terminates normally,
it changes the
mode to 0666.
Aborted runs may leave the files with mode
0222 and the
.I uulog
program will not read or remove them.
To remove them, either use
.I rm ,
.I uuclean ,
or change the mode to 0666 and let
.I uulog
merge them with the
.I LOGFILE .
.SH
STST \- system status files
.LP
These files are created in the spool directory by the
.I uucico
program.
They contain information of failures such as login, dialup or
sequence check and will contain a
.I TALKING
status when to machines are conversing.
The form of the file name is
.IP
\fBSTST\fR.sys
.LP
where
.I sys
is the remote system name.
.LP
For ordinary failures (dialup, login), the file will prevent
repeated tries for about one hour.
For sequence check failures, the file must be removed before
any future attempts to converse with that remote system.
.LP
If the file is left due to an aborted run, it may contain a
.I TALKING
status.
In this case, the file must be removed before a conversation
is attempted.
.SH
LCK \- lock files
.LP
Lock files are created for each device in use (e.g. automatic calling
unit) and each system conversing.
This prevents duplicate conversations and multiple attempts to use the
same devices.
The form of the lock file name is
.IP "" 12
\fBLCK..\fRstr
.LP
where
.I str
is either a device or system name.
The files may be left in the spool directory if runs abort.
They will be ignored (reused) after a time of about 24 hours.
When runs abort and calls are desired before the time limit,
the lock files should be removed.
.SH
Shell Files
.LP
The
.I uucp
program will spool work and attempt to start the
.I uucico
program, but the starting of
.I uucico
will sometimes fail.
(No devices available, login failures etc.).
Therefore, the
.I uucico
program should be periodically started.
The command to start
.I uucico
can be put in a ``shell'' file with a command to merge
.I LOG
files and started by a crontab entry on an hourly basis.
The file could contain the commands
.IP
.I program /uulog
.br
.I program /uucico
\ \ \-r1
.LP
Note that the ``\-r1'' option is required to start the
.I uucico
program in
.I MASTER
mode.
.LP
Another shell file may be set up on a daily basis to remove
.I TM ,
.I ST
and
.I LCK
files
and
.I C.
or
.I D.
files for work which can not be accomplished for
reasons like bad phone number, login changes etc.
A shell file containing commands like
.IP
.I program /uuclean
\ \ \-pTM \-pC. \-pD.
.br
.I program /uuclean
\ \ \-pST \-pLCK \-n12
.LP
can be used.
Note the ``\-n12'' option causes the
.I ST
and
.I LCK
files older than 12 hours to be deleted.
The absence of the ``\-n'' option will use a three day time
limit.
.LP
A daily or weekly shell should also be created
to remove or save old
.I LOGFILE s.
A shell like
.IP
cp
.I spool /LOGFILE
\ \ 
.I spool /o.LOGFILE
.br
rm
.I spool /LOGFILE
.LP
can be used.
.SH
Login Entry
.LP
One or more logins should be set up for
.I uucp .
Each of the ``/etc/passwd'' entries should
have the
``\fIprogram\fR/uucico''
as the shell to be executed.
The login directory is not used, but if the system
has a special directory for use by the users for
sending or receiving file, it should as the
login entry.
The various logins are used in conjunction with the
.I USERFILE
to restrict file access.
Specifying the
.I shell
argument limits the login to the use of uucp
(
.I uucico )
only.
.SH
File Modes
.LP
It is suggested that the owner and file modes of various
programs and files be set as follows.
.LP
The programs
.I uucp ,
.I uux ,
.I uucico
and
.I uuxqt
should be owned by the
.I uucp
login with the ``setuid'' bit set and only execute
permissions (e.g. mode 04111).
This will prevent outsiders from modifying the programs
to get at a standard
.I shell
for the
.I uucp
logins.
.LP
The
.I L.sys ,
.I SQFILE
and the
.I USERFILE
which are put in the
.I program
directory should be owned by
the
.I uucp
login and set with mode 0400.
.SG MH-1273-DAN-unix