The node software was developed by
Tomi Manninen
and was based on the original PMS program. It provides a fairly
complete and flexible node capability that is easily configured. It
allows users once they are connected to make Telnet, NET/ROM, ROSE, and
AX.25 connections out and to obtain various sorts of information such
as Finger, Nodes and Heard lists etc. You can configure the node to
execute any Linux command you wish fairly simply.
The node would normally be invoked from the ax25d
program although it is also capable of being invoked from the TCP/IP
inetd program to allow users to telnet to your
machine and obtain access to it, or by running it from the command
line.
The node.conf file is where the main configuration of the node
takes place. It is a simple text file and its format is as follows:
# /etc/ax25/node.conf
# configuration file for the node(8) program.
#
# Lines beginning with '#' are comments and are ignored.
# Hostname
# Specifies the hostname of the node machine
hostname radio.gw.vk2ktj.ampr.org
# Local Network
# allows you to specify what is consider 'local' for the
# purposes of permission checking using nodes.perms.
localnet 44.136.8.96/29
# Hide Ports
# If specified allows you to make ports invisible to users. The
# listed ports will not be listed by the (P)orts command.
hiddenports rose netrom
# Node Identification.
# this will appear in the node prompt
NodeId LINUX:VK2KTJ-9
# NET/ROM port
# This is the name of the NET/ROM port that will be used for
# outgoing NET/ROM connections from the node.
NrPort netrom
# Node Idle Timeout
# Specifies the idle time for connections to this node in seconds.
idletimout 1800
# Connection Idle Timeout
# Specifies the idle timer for connections made via this node in
# seconds.
conntimeout 1800
# Reconnect
# Specifies whether users should be reconnected to the node
# when their remote connections disconnect, or whether they
# should be disconnected complete.
reconnect on
# Command Aliases
# Provide a way of making complex node commands simple.
alias CONV "telnet vk1xwt.ampr.org 3600"
alias BBS "connect radio vk2xsb"
# External Command Aliases
# Provide a means of executing external commands under the node.
# extcmd <cmdname> <flag> <userid> <command>
# Flag == 1 is the only implemented function.
# <command> is formatted as per ax25d.conf
extcmd PMS 1 root /usr/sbin/pms pms -u %U -o VK2KTJ
# Logging
# Set logging to the system log. 3 is the noisiest, 0 is disabled.
loglevel 3
# The escape character
# 20 = (Control-T)
EscapeChar 20 |
The node allows you to assign permissions to users. These permissions
allow you to determine which users should be allowed to make use of options
such as the (T)elnet, and (C)onnect commands, for example, and which
shouldn't. The node.perms file is where this information is stored
and contains five key fields. For all fields an asterisk `*'
character matches anything. This is useful for building default rules.
- user
The first field is the callsign or user to which the permissions should apply.
Any SSID value is ignored, so you should just place the base callsign here.
- method
Each protocol or access method is also given permissions. For example you
might allow users who have connected via AX.25 or NET/ROM to use the (C)onnect
option, but prevent others, such as those who are telnet connected from a
non-local node from having access to it. The second field therefore allows
you to select which access method this permissions rule should apply to.
The access methods allowed are:
- port
For AX.25 users you can control permissions on a port by port basis too if you
choose. This allows you to determine what AX.25 are allowed to do based on
which of your ports they have connected to. The third field contains the port
name if you are using this facility. This is useful only for AX.25 connections.
- password
You may optionally configure the node so that it prompts users to enter a
password when they connect. This might be useful to help protect specially
configured users who have high authority levels. If the fourth field is
set then its value will be the password that will be accepted.
- permissions
The permissions field is the final field in each entry in the file.
The permissions field is coded as a bit field, with each facility having a bit
value which if set allows the option to be used and if not set prevents the
facility being used. The list of controllable facilities and their
corresponding bit values are:
To code the permissions value for a rule, simply take each of the permissions
you want that user to have and add their values together. The resulting number
is what you place in field five.
A sample nodes.perms might look like:
# /etc/ax25/node.perms
#
# The node operator is VK2KTJ, has a password of 'secret' and
# is allowed all permissions by all connection methods
vk2ktj * * secret 255
# The following users are banned from connecting
NOCALL * * * 0
PK232 * * * 0
PMS * * * 0
# INET users are banned from connecting.
* inet * * 0
# AX.25, NET/ROM, Local, Host and AMPR users may (C)onnect and (T)elnet
# to local and ampr hosts but not to other IP addresses.
* ax25 * * 159
* netrom * * 159
* local * * 159
* host * * 159
* ampr * * 159 |
The node program would normally be run by the
ax25d program. To do this you need to add
appropriate rules to the /etc/ax25/ax25d.conf
file. In my configuration I wanted users to have a choice of either
connecting to the node or connecting to other
services. ax25d allows you to do this by cleverly
creating creating port aliases. For example, given the
ax25d configuration presented above, I want to
configure node so that all users who connect to
VK2KTJ-1 are given the node. To do this I add the
following to my /etc/ax25/ax25d.conf file:
[vk2ktj-1 via radio]
default * * * * * 0 root /usr/sbin/node node |
This says that the Linux kernel code will answer any connection
requests for the callsign `VK2KTJ-1' heard on the
AX.25 port named `radio', and will cause the
node program to be run.
If you want users to be able to telnet a port on your machine and obtain
access to the node you can go this fairly easily. The first thing
to decide is what port users should connect to. In this example I've
arbitrarily chosen port 4000, though Tomi gives details on how you could
replace the normal telnet daemon with the node in his documentation.
You need to modify two files.
To /etc/services you should add:
node 3694/tcp #OH2BNS's node software |
and to /etc/inetd.conf you should add:
node stream tcp nowait root /usr/sbin/node node |
When this is done, and you have restarted the inetd program any user
who telnet connects to port 3694 of your machine will be prompted to login
and if configured, their password and then they will be connected to the
node.
