Dialers - Lists modems used for uucp remote communications
links
/usr/lib/uucp/Dialers
The /usr/lib/uucp/Dialers file lists the modems used by
the uucp program and specifies the initial handshaking
necessary to establish remote communications links. Handshaking
is a series of expect-send sequences that specify
the initial communications that occur on a link before it
is ready to send or receive data. Using the handshaking,
the local and remote systems confirm that they are compatible
and configured to transfer data.
The Dialers file contains an entry for each autodialer
that is included in /usr/lib/uucp/Devices file. It also
contains entries specifying no handshaking for direct
hardware links (the direct entry) and TCP/IP links (the
TCP entry). The first field of the Dialers file, which
specifies the dialer, is matched to the fifth field of the
Devices file, the Dialer-Token Pairs field, to determine
handshaking when making a connection.
Note that only someone with superuser authority can edit
the Dialers file, which is owned by the uucp program login
ID.
Fields in the Dialers File [Toc] [Back]
Every modem is listed on a line by itself in the Dialers
file. Each line consists of three groups of information:
the Dialer Name field, the Dial Tone and Wait Characters
field, and the Handshaking field. The first field in the
Dialers file, the Dialer Name field, specifies the type of
autodialer (modem) used in the connection. It matches the
fifth field in the /usr/lib/uucp/Devices file, the DialerToken
Pairs field. When a particular device is used to
make a connection, uucp uses the Dialer-Token Pairs field
in the Devices file to find the handshaking entry in the
Dialers file. If your system has direct hardware connections
to one or more remote systems, include an entry with
a Dialer Name of direct. Similarly, if your system uses
TCP/IP to connect to one or more other systems, include an
entry with a Dialer Name of TCP. These entries correspond
to the word direct or the word TCP in the Dialer-Token
Pairs field of entries in the /usr/lib/uucp/Devices file.
Omit the Dial Tone and Wait Characters field and the Handshaking
field, since no handshaking is needed on these
connections. The second field, the Dial Tone and Wait
Characters field, consists of two sets of two characters,
for a total of four entries. These characters comprise a
translation string. In the actual telephone number of the
remote modem, the first character in each string is mapped
to the second character in that set.
------------------------------------------------------------
Entry BAction
------------------------------------------------------------
=,-, Translates the telephone number. Any = (equal
sign) represents wait for dial tone and any -
(dash) represents pause.
"" Waits for nothing; continues with the rest of the
string. This field generally translates the = and -
characters into whatever the dialer uses for wait
for dial tone and pause. For direct and TCP
entries, omit this field.
------------------------------------------------------------
The handshaking, or dialer negotiations, is an
expect-send sequence of ASCII strings. It is given
in the
Handshaking field, which comprises the remainder of
the entry. This string is generally used to pass
telephone numbers to a modem, or to make a connection
to another system on the same data switch as
the local system. The string tells the cu or ct
programs or the uucico daemon the sequence of characters
to use to dial out on a particular type of
modem. If the connection succeeds, the line in the
Dialers file is interpreted to perform the dialer
negotiations.
The handshaking characters include entries such as
\d to specify a delay, \p for a pause, \r for a
carriage return, and \c for a newline. To determine
the appropriate entries in the handshaking
string, refer to the documentation that accompanied
the modems that you are including in the Dialers
file, and to the list of expect-send sequences
given in the /usr/lib/uucp/Systems file format. For
direct and TCP entries, omit this field.
Several types of Dialers file entries are shown below.
Setting Up Entries in the Dialers File [Toc] [Back]
The following example lists several entries in a typical
Dialers file:
hayes =,-, "" \dAT\r\c OK \pATDT\T\r\c CONNECT penril
=W-P "" \d > s\p9\c )-W\p\r\ds\p9\c-) y\E\TP >
9\c OK ventel =&-% "" \r\p \r\p-\r\p-$ <K\D%%\r>\c
ONLINE! vadiac =K-K "" \005\p *-\005\p-* D\p BER?
\E\D\e \r\c LINE direct TCP
Note that in the Dialers file, each entry must be
entirely on one line.
Note that the next to last entry in this example
consists only of the word direct. This entry indicates
that hardwired connections do not require any
handshaking. Similarly, the last entry, TCP, indicates
that TCP/IP connections require no handshaking.
The following example interprets the first
line in the preceding Dialers file. This is a
standard entry that may be included in your Dialers
file with modifications for use at your site.
hayes =,-, "" \dAT\r\c OK \pATDT\T\r\c CONNECT
The two sequences =,-, and "" comprise the Dial
Tone and Wait Characters field. The remaining
strings comprise the Handshaking field. Following
is an explanation of how each entry affects the
action of the dialer. Translates the telephone
number. Any = (equal sign) represents wait for
dial tone and any - (dash) represents pause. Waits
for nothing; continues with the rest of the string.
Delays, then sends AT (the Hayes Attention prefix).
Sends a carriage return (r) followed by a newline
(c). Waits for OK from the remote modem, signaling
that the first part of the string was executed.
Pauses (p), then sends ATDT. AT is again the Hayes
Attention prefix, D represents a dialing signal,
and T represents a dial tone. Sends the telephone
number, which is specified in the
/usr/lib/uucp/Systems file, with dial-code translation
from the /usr/lib/uucp/Dialcodes file. Sends
a carriage return and a newline following the number.
Waits for CONNECT from the remote modem, signaling
that the modems are connected at the baud
rate specified in the /usr/lib/uucp/Devices file.
Note that if you need to modify this example for
use at your site and are unsure about the appropriate
entries in the handshaking string, refer to the
documentation that accompanied the modems that you
are including in the Dialers file.
Setting Up the Direct Entry [Toc] [Back]
If your uucp configuration includes hardwired connections,
the Dialers file must contain the direct entry. Enter:
direct
This entry indicates that hardwired connections do not
require any handshaking. It corresponds to the word
direct in the Dialer-Token Pairs field of the entries for
hardwired devices in the /usr/lib/uucp/Devices file.
Setting Up the TCP/IP Entry
If your uucp configuration includes TCP/IP connections,
the Dialers file must contain the TCP entry. Enter: TCP
This entry indicates that TCP/IP connections do not
require any handshaking. It corresponds to the word TCP
in the Dialer-Token Pairs field of the entries for TCP/IP
connections in the /usr/lib/uucp/Devices file.
Setting Up Entries for Both Local and Remote Systems [Toc] [Back]
The following examples illustrate the entries needed in
the Dialers file to correspond to entries in the
/usr/lib/uucp/Devices file for both local and remote systems
so that the two systems can communicate using the
uucp program.
These files are set up to connect systems venus and merlin
over a telephone line using modems. System venus is considered
the local system, and system merlin is considered
the remote system. On both systems, the tty1 device is
hooked to a hayes modem at 1200 baud. The
/usr/lib/uucp/Devices file on system venus must contain
the following entry for the connection to remote system
merlin: ACU tty1 - 1200 hayes The Dialers file on system
venus must contain the following entry for its modem:
hayes =,-, "" \dAT\r\c OK \pATDT\T\r\c CONNECT The
/usr/lib/uucp/Devices file on system merlin must contain
the following entry for the connection to system venus:
ACU tty1 - 1200 hayes The Dialers file on system merlin
must contain the following entry for its modem: hayes
=,-, "" \dAT\r\c OK \pATDT\T\r\c CONNECT
Troubleshooting Connection Problems [Toc] [Back]
When establishing a connection between a local and a
remote system using a telephone line and modem, the uucp
program consults the Dialers file. (The uucp program also
checks the /usr/lib/uucp/Systems file to make sure it contains
a listing for the specified remote computer.) If
users report a faulty connection, use the uucico command
to debug the connection problem. For example, if users
are experiencing difficulties connecting to remote system
venus, enter: /usr/lib/uucp/uucico -r1 -svenus -x9
where -r1 specifies the server mode, -svenus is the name
of the remote system to which you are trying to connect,
and -x9 is the debug level that produces the most detailed
debugging information.
Expect-send debugging output produced by the uucico command
can come either from information in the Dialers file
or from information in the /usr/lib/uucp/Systems file. If
the relevant line in the Dialers file is not set up correctly
for the specified modem, the uucp program will
probably display the following error message:
DIALER SCRIPT FAILED
If the dialer script fails, verify the following: Make
sure that both the local and the remote modems are turned
on, that they are both set up correctly, and that the
telephone number of the remote modem is correct. Check
the Dialers file and make sure the information is correctly
specified for the local modem. If possible, check
the Dialers file on the remote system also. Check the
documentation that came with your modem to make sure you
have used the correct expect-send sequence characters in
the Dialers file.
Contains all the configuration files for the uucp program,
including the Dialers file Contains information about
available devices Contains dial-code abbreviations
Describes accessible remote systems
Daemons: uucico(8)
Commands: ct(1), cu(1), uutry(1)
Dialers(4)
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