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Copyright CourseWare Technologies Inc. 1985-88
Lesson - 5
UUCP COMMUNICATIONS
MENU
UUCP Communications|Topics to Learn|5-0|15,56
# Topic
--- -------
1 - Communication Using uucp
2 - Administering the UUCP System
3 - Locating UUCP Software
4 - Scheduling in the /usr/lib/crontab File
5 - Access Control
6 - The L.sys File
7 - The L-devices File
8 - The L-dialcodes File
9 - Setting up the Calling Port
10 - Cleanup with /etc/rc
11 - Conclusion
12 - Lesson Review
0 - Return to the Main Menu
P1
UUCP Communications|Communication Using uucp|5-1.1|9,55
Sending mail to a system is just one of many
functions in the UUCP command family. uucp is one
of most reliable, portable, and cheapest means for
data transfer between UNIX systems.
UUCP family commands perform file transfers
between systems as well as system calls, maintain
usage statistics, and insure security.
P2
UUCP Communications|Communication Using uucp|5-1.2|16,55
The uucp command is used to copy files between
systems.
uucp copies each source file to the named
destination-file. A filename may be a pathname on
your machine, or may have the form system-name!pathname
where the system name is taken from a list of system
names that uucp knows about.
For example, to transfer the file admin to
the directory /usr/learn on the system dual, the
command (under the C-Shell) would be:
uucp admin dual\!/usr/learn
P3
UUCP Communications|Communication Using uucp|5-1.3|8,55
uucp has some built-in knowledge, especially
when it comes to the home directories. When a user's
login name is prefixed with ~ in the uucp command line,
uucp will substitute the user's home directory. For
example, the command:
uucp dual!~yori,
replaces ~yori with yori's HOME directory, /usr/yori.
P4
UUCP Communications|Communication Using uucp|5-1.4|11,57
Often when you are transferring data that is not
sensitive, you may send it to the UUCP PUBLIC directory,
/usr/spool/uucppublic
For the uucp account, the HOME directory is:
/usr/spool/uucppublic
so when an absolute pathname is prefixed with ~, uucp
interprets ~ as /usr/spool/uucppublic.
P5
UUCP Communications|Communication Using uucp|5-1.5|7,44
If the command is:
uucp admin cti!~/yori/learn/admin,
uucp will copy the admin file into the
/usr/spool/uucppublic/yori/learn/ directory.
P6
UUCP Communications|Communication Using uucp|5-1.6|11,56
Your safest bet for a successful uucp transfer
is through the /usr/spool/uucppublic directories on
both systems. For example,
uucp cti!~/yori/admin ~/miked/admin
will copy the file admin from the directory
/usr/spool/uucppublic/yori on the remote system cti
into the file admin on the host system in the directory:
/usr/spool/uucppublic/miked
P7
UUCP Communications|Communication Using uucp|5-1.7|5,54
The command for forward only copying of files
from your host system to another system to which your
system has a direct wire or a telephone connection is:
uuto
UUCP Communications|Communication Using uucp|5-1.7|3,54
The -nuser option to the uucp command will
notify user, that is, send user mail that the
file was sent.
P8
UUCP Communications|Communication Using uucp|5-1.8|12,54
Often you wish to use another system's resources
such as tape drives, plotters, or printers.
You may do this by transferring files first, then
logging in remotely with cu, and executing the necessary
commands; or you can accomplish all this by using the
powerful UUCP-family command:
uux
the execute command on a UNIX system.
P9
UUCP Communications|Communication Using uucp|5-1.9|15,52
The command that lets you check the status of
UUCP activity on your system is uulog. uulog allows
you to obtain per user and per system uucp activity
information.
To obtain the status of UUCP activities for
the user david use:
uulog -udavid
To obtain the status of UUCP activities of the
host system with the system cti use the command:
uulog -scti
P10
UUCP Communications|Administering the UUCP System|5-2.1|13,57
The actual usage of the communication commands
is rather simple. Because mail, cu and uucp are
themselves part of the network, it is important that
the supporting UUCP files are set up properly.
As a system administrator, you will have the task
of setting up the UUCP system, if someone else has not
done so already.
It is the intention of this section to guide you
painlessly through the UUCP setup procedure!
P11
UUCP Communications|Administering the UUCP System|5-2.2|11,60
Provided you follow this lesson closely, you
should have a sufficient background to start using
and, if necessary, to set up the required UUCP
software.
Remember that after you set up the first UUCP
system, the second one will be infinitely easier.
You will see examples in the next section.
P12
UUCP Communications|Locating UUCP Software|5-3.1|5,54
If you're lucky, everything for UUCP transfer is
set up and the only thing you need to do is to type
in the uucp command. If you're not lucky, then you
have an even better reason to learn the "unmystical"
procedure for setting up and managing the UUCP system.
P13
UUCP Communications|Locating UUCP Software|5-3.2|10,54
Support for uucp is located in three major
directories:
* /usr/bin (user commands)
* /usr/lib/uucp (operational commands)
* /usr/spool/uucp (the spooling area)
First, you should make sure these directories
contain all of the programs and files that uucp needs.
P14
UUCP Communications|Locating UUCP Software|5-3.3|6,50
In the /usr/bin directory you should find:
* uucp,
* uux,
* uulog, and
* uuname.
UUCP Communications|Locating UUCP Software|5-3.3|12,50
In the /usr/bin directory you should find:
* uucp,
* uudecode,
* uuencode,
* uulog,
* uuname,
* uupoll,
* uuq,
* uusend,
* uusnap, and
* uux.
P15
UUCP Communications|Locating UUCP Software|5-3.4|9,54
Check the /usr/lib/uucp directory for the
programs:
* uucico,
* uuclean, and
* uuxqt.
If these are missing, check your distribution kit,
or call your UNIX system sales office.
P16
UUCP Communications|Locating UUCP Software|5-3.5|9,54
Next, check the /etc/passwd file for the login
name uucp, and verify that the home directory is
/usr/spool/uucppublic.
Also make sure that the login shell for UUCP is
/usr/lib/uucp/uucico. uucico is the copy in, copy
out program that performs actual data transfer for
UUCP. Therefore, when uucp logs in, uucico is invoked
to perform data transfer.
P17
UUCP Communications|Scheduling in the crontab File|5-4.1|8,54
To assure that a constant attempt is being made
to transfer the queued files, enter uucico into
your /usr/lib/crontab file. (If you don't have
one, now is a good time to create one.)
The line should look something like this:
1 * * * * su - uucp -c /usr/lib/uucp/uucico -r1
P18
UUCP Communications|Scheduling in the crontab File|5-4.2|11,54
As uucp operates, it creates and/or expands
many files in the UUCP directories. The uuclean
program will clean up these files for you. Thus
/usr/lib/uucp/uuclean should also be placed into
the /usr/lib/crontab file.
The line should look something like this:
1 * * * * su - uucp -c /usr/lib/uucp/uuclean -p
(This says that an attempt is made every minute.)
P19
UUCP Communications|Access Control|5-5.1|13,55
The file that contains the information about
who can access the files on your system is
/usr/lib/uucp/USERFILE.
USERFILE specifies four types of constraints:
1. files that can be accessed by a user of the host
machine,
2. files that can be accessed from a remote computer,
3. login name used by a particular remote computer,
4. whether a remote computer should be called back
to confirm its identity.
P20
UUCP Communications|Access Control|5-5.2|7,54
Each line in the file USERFILE has the format:
login,sys [c] pathname [pathname]
where:
login is the login name,
sys is the system name for the remote computer,
c is the optional call-back flag.
P21
UUCP Communications|Access Control|5-5.3|9,52
Rather than going into a more theoretical
discussion, let's look at some examples of the
information that goes into the USERFILE.
a,b /usr/admin
allows machine b to log in with the name a and
request the transfer of all files whose pathnames
begin with /usr/admin.
P22
UUCP Communications|Access Control|5-5.4|15,54
In /usr/lib/uucp/USERFILE, the line
paul, /usr/paul
allows the user paul to issue commands for files
whose names start with /usr/paul while the lines:
a,b /usr/paul /usr/spool
a, /usr/spool
mean that any remote machine can login with the login
name a. However, if the system name is not b, then the
system can ask for transfer of files beginning with
with /usr/spool. If the system is b, it can also
read files from /usr/paul.
P23
UUCP Communications|Access Control|5-5.5|6,54
The lines that allow any user to transfer files
beginning with /usr, and the lines that allow the
user root to transfer any file are:
root, /
, /usr
P24
UUCP Communications|The L.sys File|5-6.1|3,50
The L.sys file contains the phone numbers
and login sequences required to establish a
connection with a UUCP daemon on another machine.
P25
UUCP Communications|The L.sys File|5-6.2|12,54
The fields of each line in the L.sys file are
as follows:
name - name of the remote system,
time - time when the remote system may be called,
device - local device that can be used for calling
the remote system,
speed - baud rate for the call,
phone - phone number,
login - login sequence ended with a password that
uucp uses to establish a login on the
remote system.
P26
UUCP Communications|The L-devices File|5-7.1|8,54
The /usr/lib/uucp/L-devices file contains the
list of all lines that are directly connected to other
systems or are available for calling other systems.
The format of this file is:
device line call-device speed protocol
P27
UUCP Communications|The L-devices File|5-7.2|11,53
Some of the possible entries in your L-devices
file, which you may need to modify include:
DIR serial 0 2400
ACU cul0 cua0 1200
DIR x25.s0 0 300 x
where DIR means direct connection; ACU stands for
automatic calling unit; serial, cu10, x25.s0 are
various lines; 0 means any call unit; 300, 1200 and
2400 are speeds, and x25 is the X25 protocol!
P28
UUCP Communications|The L-dialcodes File|5-8.1|11,52
The /usr/lib/uucp/L-dialcodes file contains a
listing of the dial-codes and any possible abbreviations
used by the system. The format of an entry is:
abbreviation dial-sequence
The line: py 165-
would establish that entry py would send 165- to the
dial unit.
P29
UUCP Communications|Setting up the Calling Port|5-9.1|10,54
You must turn off the login capability from the
port that you plan to use for calling another system.
You do this by changing a line in /etc/inittab to
hold back the getty process, that is, change
getty ttya3 ....
to
getty ttya3 ...
UUCP Communications|Setting up the Calling Port|5-9.1|10,54
You must turn off the login capability from the
port that you plan to use for calling another system.
You do this by changing a line in /etc/ttys to hold
back the getty process, that is, change:
1mttya3
to
0mttya3
UUCP Communications|Setting up the Calling Port|5-9.1|15,50
You must create the appropriate device for your
modem (connected, for example, to ttya) with the
following series of commands:
# cd /dev
# mknod cua0 c 12 128
# chmod 600 cua0
# chown uucp cua0
# mv ttya ttyd0
Then edit /etc/ttys to include an entry
for ttyd0:
13ttyd0
P30
UUCP Communications|Cleanup with /etc/rc|5-10.1|10,60
Periodically you will need to clean up the UUCP
status files to which uucp writes every time it processes
a command. Similarly, you need to delete various lock
files. So please put the following lines into your
/etc/rc file:
rm -f /usr/spool/uucp/LCK* (locks up port)
rm -f /usr/spool/uucp/LOGFILE (log of UUCP activity)
rm -f /usr/spool/uucp/SYSLOG (log of UUCP file transfers)
rm -f /usr/spool/uucp/STS* (locks access to named system)
P31
UUCP Communications|Cleanup with /etc/rc|5-10.2| 6,54
The LCK* files lock up the port, and the
STST.sysname file locks up the access to the system
sysname while the transmission is in progress. These
lock files remain if communication fails for any reason.
The LOGFILE and SYSLOG are UUCP statistical files.
P32
UUCP Communications|Conclusion|5-11.1|10,60
To review, when setting up the UUCP software you
may have to:
* modify the login sequence more than once in the L.sys
file,
* verify that the dial out port is disabled,
* verify that the protections in the USERFILE and the
devices in the L-devices file are properly set up, and
* use the /usr/spool/uucp/LOGFILE and /usr/spool/uucp/ERRLOG
files to diagnose errors if any do occur.