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14 <h2>Connecting to other Clusters</h2>
19 <address><a href="mailto:djk@tobit.co.uk">Dirk Koopman G1TLH</a></address>
21 <!-- Created: Sun Dec 13 20:25:14 GMT 1998 -->
23 Last modified: Sun Sep 2 20:44:59 BST 2001
25 <p>At the moment, anybody can connect inwards at any time from outside, either by ax25 or by
26 telnet (assuming you have followed the instructions in <a href="install.html">installation</a>
27 instructions. However, in order to connect outwards, you will need to create <em>connect</em> scripts.
29 <p><em>Connect</em> scripts live in the <tt>/spider/connect</tt> directory and are simple ascii scripts
30 that are written using a normal editor. There are a couple of examples in the issue directory.
32 <p>The first example is a simple telnet (TCP/IP) connect to port 7000 of WR3D (this will actually
33 work if you have or make an arrangement to connect to WR3D)[oh, and substitute x1xxx for your real
39 connect telnet wr3d.dxcluster.net 7000
44 <p>For a connect that requires a login and execution of the programs
45 from a normal shell, do:-</p>
49 connect telnet dirkl.tobit.co.uk
52 '\$' 'cd /spider/perl'
53 # set the line to prevent echoing, leaving this out will
54 # confuse whole networks for hours!
56 # tell GB7DJK that you are GB7DJK-1
57 '\$' '/spider/src/client gb7djk-1 telnet'
58 # tell GB7DJK-1 that it is connected to GB7DJK
59 # you can leave this out if you call this script 'gb7djk'
63 <p>a ax25 example (connecting from GB7DJK, to GB7DXM via my local BPQ node and one X1J intermediate node):-
66 abort (Busy|Sorry|Fail)
67 # don't forget to chmod 4775 netrom_call!
68 connect ax25 /usr/sbin/netrom_call bbs gb7djk-0 g1tlh-0
71 '*** Connect' 'c gb7dxm'
75 <p>The <tt>-0</tt> ssid is important if you want it to work reliably. Obviously if you are
76 using a different ssid then you would use that. You can use the Netrom alias instead if it
77 it is in the machines node table</p>
79 <p>A AGW Engine example would be very similar and look like this:-</p>
83 abort (Busy|Sorry|Fail)
87 'linked to' 'c gb7dxm'
91 <p>A connection is started manually by typing in <tt>connect <scriptname></tt> on a sysop enabled
92 <tt>client.pl</tt> session. For example:-</p>
95 G1TLH de GB7DJK 13-Dec-1998 2041Z > connect gb7djk-1
96 connection to GB7DJK-1 started
97 G1TLH de GB7DJK 13-Dec-1998 2043Z >
100 <p>Consider the following specific example, it is located in the file <tt>/spider/connect/gb7djk-1</tt> :-</p>
103 <span class=cmd>timeout 15</span>
104 <span class=cmd>connect telnet dirkl.tobit.co.uk</span>
105 <span class=expect>'login'</span> <span class=send>'gb7djk'</span>
106 <span class=expect>'ssword'</span> <span class=send>'gb7djk'</span>
109 <p>You can watch the progress of the connection (if you have <tt>connect</tt>
110 debugging enabled [<tt>set/debug connect</tt>]) on the
111 <tt>cluster.pl</tt> screen and you should see something like this:-</p>
114 <- D G1TLH connect gb7djk-1
115 -> D G1TLH connection to GB7DJK-1 started
116 -> D G1TLH G1TLH de GB7DJK 13-Dec-1998 2046Z >
117 <span class=cmd>timeout set to 15</span>
118 <span class=cmd>CONNECT sort: telnet command: dirkl.tobit.co.uk</span>
119 CHAT "login" -> "gb7djk"
121 Red Hat Linux release 5.1 (Manhattan)
122 Kernel 2.0.35 on an i586
124 <span class=expect>received "login: "</span>
125 <span class=send>sent "gb7djk"</span>
126 CHAT "word" -> "gb7djk"
130 <span class=expect>received "Password: "</span>
131 <span class=send>sent "gb7djk"</span>
132 Connected to GB7DJK-1, starting normal protocol
133 <- O GB7DJK-1 telnet
135 GB7DJK-1 channel func state 0 -> init
137 <- D GB7DJK-1 Last login: Sun Dec 13 17:59:56 from dirk1
138 <- D GB7DJK-1 PC38^GB7DJK-1^~
139 <- D GB7DJK-1 PC18^ 1 nodes, 0 local / 1 total users Max users 0 Uptime 0 00:00^5447^~
143 <p>I have coloured the commands in an attempt to make it clear as to what goes on, where and why.
144 <span class=cmd>These coloured lines are miscellaneous commands</span>, the <span class=expect>things
145 that are this colour are the strings I am looking for (what I am "expecting")</span>
146 and the <span class=send>things that are this colour
147 are the commands I am going to send when I see the "expect" strings in the input</span>.</p>
149 <p>The script starts by setting the timeout to 15 seconds, then starts
150 the connection. It is <b>important</b> to note that, in the case of
151 an ax25 connection (usually) this will be the callsign of the <i>first hop</i> along the
152 route that you are going to take to the destination, so this will be typically the callsign
153 of your local node.</p>
155 <p>You will notice that the script waits until it sees the left hand string
156 of the pair and <b>only then</b> does it send the,
158 hand side. This is called a <i>State Machine</i>.</p>
160 <p>A <i>state machine</i> "walks" through a conversation (in this case) looking
161 for "states" (in this case particular strings) and then performs some
162 "action" (usually some kind of connect command for the type of system
163 you are trying to navigate). When one "state" "fires" (detects the string
164 are looking for), it sends the command associated with that state and then
165 moves onto the next "state", in our case: the next line.</p>
167 <p><b>PLEASE NOTE</b>: the colouration in the above example is for illustrative purposes
168 only, the debug output is all one colour.</p>
170 <p>The connect scripts consist of lines which start with the
171 following keywords or symbols:-</p>
175 <li><b>#</b> All lines starting with a <b>#</b> are
176 ignored, as are wholly blank lines.
179 <li><b>timeout</b> followed by a number is the number of
180 seconds to wait for a command to complete. If there is no
181 <b>timeout</b> specified in the script then the default is 60
185 <li><b>abort</b> is a regular expression containing one or
186 more strings to look for to abort a connection. This is a perl
187 regular expression and is executed ignoring case.
190 <li><b>connect</b> followed by <b>ax25</b>, <b>telnet</b> or <b>agw</b>
191 and some type dependent information.
194 <b>telnet</b> connection, there can be up to two parameters,
195 the first is the ip address or hostname of the computer you
196 wish to connect to and the second is the port number you want
197 to use (this can be left out if it is a normal telnet
200 <p>In the case of an <b>ax25</b> session then this would
201 normally be a call to <tt>/usr/sbin/ax25_call</tt> or
202 <tt>/usr/sbin/netrom_call</tt> as in the example above. It is your
203 responsibility to get your node and other ax25 parameters to
204 work before going down this route!
206 <p>For <b>agw</b> connections you will need a port number (starting
207 from 1) and the callsign of the first "hop" along the way.
210 <li><b>'</b> is the delimiting character for a word or
211 phrase of an expect/send line in a <tt>chat</tt> type
212 script. The words/phrases normally come in pairs, either can
213 be empty. Each line reads input from the connection until it
214 sees the string (or perl regular expression) contained in the
215 left hand string. If the left hand string is empty then it
216 doesn't read or wait for anything. The comparison is done
219 <p>When the left hand string has found what it is looking (if
220 it is) then the right hand string is sent to the connection.
222 <p>This process is repeated for every line of <tt>chat</tt> script.
225 <li><b>client</b> starts the connection, put the arguments
226 you would want here if you were starting the client program
227 manually. You only need this if the script has a different
228 name to the callsign you are trying to connect to (i.e. you
229 have a script called <tt>other</tt> which actually connects to
230 <tt>GB7DJK-1</tt> [instead of a script called
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238 <span class=copy>Copyright © 1998 by Dirk Koopman G1TLH. All Rights Reserved</span><br>
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