Linux Network Administrator Manual (12)

Article title: Linux Network Administrator Manual (12 ). Linux is a technology channel of the IT lab in China. Includes basic categories such as desktop applications, Linux system management, kernel research, embedded systems, and open source.
Chapter 4 management of Taylor UUCP
12.1 Historical Review
UUCP was designed by Mike Lesk of AT&T Bell Labs in the end of 1970s to provide simplicity on public telephone lines
. Because many people who want to have email and Usenet News on their machines still use modem
Communication, so UUCP is still very popular. Although there are many implementations running on various types of hardware platforms and operating systems
However, they are highly compatible.
However, despite the fact that many of the software has become "standard" in various ways over the past few years, there has been no UUCP software
Called UUCP. Since its implementation in the first version in 1976, it has undergone a solid evolution process. Currently,
There are two main types, which are different in hardware support and configuration. They all have a variety of implementations, each
There are some minor differences in implementation.
One of them is the so-called "version 2 UUCP", which is Mike Lesk, David A. Novitz, and Greg Chesson
Implemented in 1977. Although this is a very old version, it is still frequently used. The latest implementation of version 2 is updated.
UUCP type ease of use.
The second type was developed in 1983 and is generally called BNU (basic network connection tool), HoneyDanBer uuucp, or simplified
HDB. This name is generated from the author's names, P. Honeyman, D. A. Novitz, and B. E. Redman. HDB test
Some shortcomings of version 2 UUCP are taken into consideration. For example, a new transfer protocol is added and each connection has a UU
All sites that communicate with CP have an independent directory.
At present, the UUCP Implementation accompanying the Linux release is Taylor UUCP 1.04. [1] This chapter is based on this version. Ta
Ylor uuucp version 1.04 was released in February 1993. In addition to the traditional configuration files, Taylor UUCP can also be
Compile to use the new style? A. k. a. "Taylor"-configuration file.
The 1.05 version has been released recently and will soon be integrated into most Linux releases. The major difference between these versions is that
You are not very familiar with the features, so you can use the information in this book to configure Taylor UUCP 1.05.
For Taylor UUCP, which is included in many Linux releases, it is usually compiled to be BNU compatible or used
R configuration scheme. The latter is more flexible and may be more obscure than the BNU configuration file.
Easy to understand, so I will introduce the Taylor configuration scheme below.
The purpose of this chapter is not to give you a detailed description of what UCP command line options are and how to use them, but to give you
An overview of how to set up an available UUCP site. The first part shows how UUCP achieves
A brief description of the process execution and file transfer. If you are not a newbie to UUCP, you can skip
Directly to the UCP configuration file section, this section explains the various files used to set UCP.
However, we will assume that you are familiar with the UUCP suite user program. These programs are uucp and uux. These two commands
For more information, see the online manual page.
In addition to the commonly used uux and uucp programs, UUCP kit also contains a series of commands for management purposes only. They are used
Monitor UUCP communication through your node, delete old log files, or aggregate statistical parameters. They will not be used here
Any description, because they are in parallel with the main UCP tasks. They have good documentation for reference and
Easy to understand. However, there is another type, which is composed of UUCP's actual "working machine. They are called uucico (
Here, cico stands for copy-in copy-out) and uuxqt-are used to execute jobs sent by remote systems.
12.1.1 more information about UUCP
If you cannot find the information you want in this chapter, you should read the documents that come with this software package. This is the description of using CMDL
Or a dozen of texinfo files configured in the configuration scheme. You can use tex and makeinfo to convert texinfo to DVI.
And GNU information files.
If you want to use the BNU or even (chilling) version 2 configuration file, here is a good book,"
Manage UUCP and Usenet "([Oreilly89]). I found it very useful. Other good information about UUCP on Linux
The source of information is Vince Skahan's UUCP-HOWTO, which is regularly delivered to comp. OS. linux. announce.
　　
Of course, there is also a newsgroup dedicated to UUCP, called comp. mail. uucp. If you have questions about Taylor UUCP
You 'd better ask them there, not in the comp. OS. linux group.
12.2 overview
12.2.1 Overview of UUCP transmission and remote execution
Jobs are a key concept for understanding UUCP ). Each transmission initiated by a user using UCP or uux is called
A job. It consists of commands executed on the remote system and file sets to be transmitted between sites. Of course
, You can omit some of them.
For example, if you have issued the following command on your host, this command causes UUCP to change the file netguide. p
S copies the file to the pablo host and enables it to execute the lpr command to print the file.
$ Uux? R pablo! Lpr! Netguide. ps
UUCP usually does not call a remote system immediately to execute a job (but you can use kermit to do so ). But now
Store the job description. This is called spooling ). Therefore
Spool directory is usually located in/var/spool/UCP. In our example
The job description contains information about the remote command to be executed (lpr), the commands that require this operation, and other
Some projects. In addition to the job description, UUCP also needs to store the input file netguide. ps.
The exact location and naming method of the offline files vary depending on some compilation options. HDB compatibility
The UUCP of is usually stored in the directory named/var/spool/uucp/site, where the site is a remote site
The name of the vertex. When compiled in Taylor configuration mode, UUCP will be false for different types of offline files on the specified site
Create a subdirectory in the offline directory.
At the specified time interval, UUCP will dial to the remote system. After the connection is established with the remote system, UUCP will transmit the description
File of the job, plus all input files. The input job will not be executed immediately, but will be closed at the end of the connection.
Later. This task is executed using uuxqt. if a job is specified on another site, it also handles the forwarding of the job.
.
To distinguish between important and unimportant jobs, UUCP assigns each job a level (grade ). This is a single word
The value range is from 0 to 9, A to Z, and a to z. The level ranges from large to small. Mail generally performs offline operations with Level B or C, while
For news, the level N is used for off-line operations. The higher the level, the earlier the job is transmitted. Level when you call UCP or uux
Use the-g flag to specify.
You can also disable the transmission of jobs of a lower level within a certain period of time. This is called the maximum number of false disconnections allowed during the conversation.
Maximum spool grade. the default value is z. Note that the terminology is ambiguous:
It is transmitted only when its level is equal to or higher than the maximum offline level.
12.2.2 uucico internal working mechanism
You need to understand why uucico needs to know something. Here we show how it actually connects to a remote system.
Quick description.
When you execute uucico on the command line? S system, it must first be physically connected. The operations performed depend on
The connection type opened? For example, when using a telephone line, it must find a modem and dial up. In
On TCP, it must call gethostbyname (3) to convert the name to a network address, find the port to open
And bind the address to the corresponding socket.
After the connection is established, you must pass an authentication process. This is often a login request from a remote system.
Name and a possible password. This is usually called a login chat ). Authentication process or
It is executed through the usual getty/login suite, or by uucico itself on the TCP socket. If you authenticate
If it succeeds, the remote system starts uucico. The local uucico copy of the initial connection is considered as the master)
The remote end is used as the slave end (slave ).
The next step is handshake phase. The Master end now sends out its own host name, and adds several signs to the slave end.
Check the logon permission of the host name, send and receive files, and so on. These symbols are used to describe (and in other cases
Medium) the maximum level of the offline files to be transferred. If this function is enabled, a dialog count or call
Check with the serial number. With this feature, the sites at both ends maintain a successful connection count, which can be used for comparison.
. If they do not match, the handshake fails. This is useful for protecting you from counterfeits.
Finally, the two uucico try to reach a common transmission protocol. This protocol guides the method of data transmission, check 1
And re-transmits data when an error occurs. Different protocols are required for different supported connection types. For example,
Telephone lines require a Conservative "security" protocol for errors, and TCP transmission is inherently reliable, so it can be used
A more effective protocol that does not require an error check.
After the handshake phase is completed, the actual transmission phase starts. Enable the selected protocol driver at both ends of the transfer. Drive
Generally, an animation initializes the protocol.
First, the master end sends all files in the queue to the remote system at a sufficiently high level of offline delivery. When it completes transmission
The slave end will be notified, and the slave end can be hung up now. At present, the slave end can either agree to hang up or control the conversation.
. This is a rule change: Now the remote system is changed to the master, while the local system is changed to the slave. New Master end
The file that is sent now. After completion, two uucico exchange and transmit messages to each other, and close the connection.
We will not describe it in more detail: Please refer to the code or any good book about UUCP for this. Also online
There is also an old article written by David A. Novitz, which provides A detailed description of the UUCP protocol. T
The aylor uuucp FAQ also discusses some details about UCP implementation methods. It is regularly delivered to comp. mail. uucp.
　　
12.2.3 uucico command line option
This section describes some of the most important command line options of uucico. For a complete list of command line options, see uucico (1
) Manual page.
-S system calls the specified system unless restricted by the call time.
-S system calls the specified (system) unconditionally ).
-R1 is in master mode.