Linux Network Admistrator's Guide

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.The port's name is chosen to match the port name given in the sys file:# /etc/uucp/port - UUCP ports# /dev/ttyS1 (COM2)port serial1type modemdevice /dev/ttyS1216speed 38400dialer nakwellThe information pertaining to the dialers is kept in yet another file called -- you guessed it -- dial.For each dialertype, it basically contains the sequence of commands that are issued to dial up a remote site, given the telephonenumber.Again, this is specified as a chat script.For example, the entry for NakWell might look like this:# /etc/uucp/dial - per-dialer information# NakWell modemsdialer nakwellchat "" AT&F OK ATDT\T CONNECTThe line starting with chat specifies the modem chat, which is the sequence of commands sent to and receivedfrom the modem to initialize it and make it dial the desired number.The \T sequence will be replaced with thephone number by uucico.To give you a rough idea how uucico deals with these configuration files, assume you issue the followingcommand:$ uucico -s pabloThe first thing uucico does is look up pablo in the sys file.From the sys file entry for pablo, it sees that itshould use the serial1 port to establish the connection.The port file tells uucico that this is a modem port, andthat it has a NakWell modem attached.uucico now searches dial for the entry describing the NakWell modem, and having found one, opens the serialport /dev/cua1 and executes the dialer chat.That is, it sends AT&F, waits for the OK response, etc.When encoun-tering the string \T, it substitutes the phone number (555-22112) extracted from the sys file.After the modem returns CONNECT, the connection has been established, and the modem chat is complete.uucico now returns to the sys file and executes the login chat.In our example, it would wait for the login:prompt, then send its username (vstout), wait for the password: prompt, and send its password (lorca).After completing authorization, the remote end is assumed to fire up its own uucico.The two then enter thehandshake phase described in the previous section.Figure 16.1 illustrates the dependencies among configuration files.Figure 16.1: Interaction of Taylor UUCP configuration files217What UUCP Needs to KnowBefore you start writing the UUCP configuration files, you have to gather some information that UUCP requires.First, you have to figure out what serial device your modem is attached to.Usually, the (DOS) ports COM1:through COM4: map to the device special files /dev/ttyS0 through /dev/ttyS3.Some distributions, such as Slack-ware, create a link called /dev/modem to the appropriate ttyS* device file, and configure kermit, seyon, andany other communication programs to use this generic file.In this case, you should use /dev/modem in yourUUCP configuration, too.The reason for using a symbolic link is that all dial-out programs use so-called lock files to signal when a serialport is in use.The names of these lock files are a concatenation of the string LCK.and the device filename, forinstance LCK.ttyS1.If programs use different names for the same device, they will fail to recognize each other'slock files.As a consequence, they will disrupt each other's session when started at the same time.This is quitepossible when you schedule your UUCP calls using a crontab entry.For details on serial port setup, please referto Chapter 4, Configuring the Serial Hardware.Next, you must find out at what speed your modem and Linux will communicate.You have to set this speed tothe maximum effective transfer rate you expect to get.The effective transfer rate may be much higher than theraw physical transfer rate your modem is capable of.For instance, many modems send and receive data at 56kbps.Using compression protocols such as V.42bis, the actual transfer rate may climb over 100 kbps.Of course, if UUCP is to do anything at all, you need the phone number of a system to call.Also, you need avalid login ID and possibly a password for the remote machine.91You also have to know exactly how to log into the system.Do you have to press the Enter key before the loginprompt appears? Does it display login: or user:? This is necessary for composing the chat script.If youdon't know, or if the usual chat script fails, try to call the system with a terminal program like kermit orminicom and record exactly what you have to do [ Pobierz całość w formacie PDF ]

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