LinuxHam - User contributions [en]

Help:Editing

2014-06-28T20:00:17Z

VK4MSL: Corrected link

#REDIRECT [[mediawikiwiki:Help:Editing]]

Help:Editing

2014-06-28T19:59:07Z

VK4MSL: This time with a link that works

#REDIRECT [[mediawikiwiki:Editing]]

Help:Editing

2014-06-28T19:56:53Z

VK4MSL: Use a redirect to send the user there directly

#REDIRECT [http://www.mediawiki.org/wiki/Help:Editing]

NET/ROM

2014-06-28T19:21:17Z

VK4MSL: Re-format the descriptions

'''NET/ROM''' was the first layer 3 protocol providing transparent routing to the packet radio user thus enabled less constraint growth of the packet radio network.

The NET/ROM protocol relies on, and uses the AX.25 ports you have created. The NET/ROM protocol rides on top of the AX.25 protocol. To configure NET/ROM on an AX.25 interface you must configure two files. One file describes the NET/ROM interfaces, and the other file describes which of the AX.25 ports will carry NET/ROM. You can configure multiple NET/ROM ports, each with its own callsign and alias, the same procedure applies for each.

== NET/ROM Configuration ==
=== Configuring /etc/ax25/nrports ===

The first is the /etc/ax25/nrports file. This file describes the NET/ROM ports in much the same way as the /etc/ax25/axports file describes the AX.25 ports. Each NET/ROM device you wish to create must have an entry in the /etc/ax25/nrports file. Normally a Linux machine would have only one NET/ROM device configured that would use a number of the AX.25 ports defined. In some situations you might wish a special service such as a BBS to have a separate NET/ROM alias and so you would create more than one.

This file is formatted as follows:

name callsign alias paclen description

Where:

;name
:is the text name that you wish to refer to the port by.
;callsign
:is the callsign that the NET/ROM traffic from this port will use. Note, this is not that address that users should connect to to get access to a node style interface. (The node program is covered later). This callsign/ssid should be unique and should not appear elsewhere in either of the /etc/ax25/axports or the /etc/ax25/nrports files.
;alias
:is the NET/ROM alias this port will have assigned to it.
;paclen
:is the maximum size of NET/ROM frames transmitted by this port.
;description
:is a free text description of the port.

An example would look something like the following:

netrom VK2KTJ-9 LINUX 236 Linux Switch Port

This example creates a NET/ROM port known to the rest of the NET/ROM network as `LINUX:VK2KTJ-9'.

This file is used by programs such as the call program.
=== Configuring /etc/ax25/nrbroadcast ===

The second file is the /etc/ax25/nrbroadcast file. This file may contain a number of entries. There would normally be one entry for each AX.25 port that you wish to allow NET/ROM traffic on.

This file is formatted as follows:

axport min_obs def_qual worst_qual verbose

Where:

;axport
:is the port name obtained from the /etc/ax25/axports file. If you do not have an entry in /etc/ax25/nrbroadcasts for a port then this means that no NET/ROM routing will occur and any received NET/ROM broadcasts will be ignored for that port.
;min_obs
:is the minimum obselesence value for the port.
;def_qual
:is the default quality for the port.
;worst_qual
:is the worst quality value for the port, any routes under this quality will be ignored.
;verbose
:is a flag determining whether full NET/ROM routing broadcasts will occur from this port or only a routing broadcast advertising the node itself.

An example would look something like the following:

radio 1 200 100 1

=== Creating the NET/ROM Network device ===

When you have the two configuration files completed you must create the NET/ROM device in much the same way as you did for the AX.25 devices. This time you use the nrattach command. The nrattach works in just the same way as the axattach command except that it creates NET/ROM network devices called `nr[0-9]'. Again, the first time you use the nrattach command it creates the `nr0' device, the second time it creates the `nr1' network devices etc. To create the network device for the NET/ROM port we've defined we would use:

# nrattach netrom

This command would start the NET/ROM device (nr0) named netrom configured with the details specified in the /etc/ax25/nrports file.

=== Starting the NET/ROM daemon ===

The Linux kernel does all of the NET/ROM protocol and switching, but does not manage some functions. The NET/ROM daemon manages the NET/ROM routing tables and generates the NET/ROM routing broadcasts. You start NET/ROM daemon with the command:

# /usr/sbin/netromd -i

You should soon see the /proc/net/nr_neigh file filling up with information about your NET/ROM neighbours.

Remember to put the /usr/sbin/netromd command in your rc files so that it is started automatically each time you reboot.

=== Configuring NET/ROM routing ===

You may wish to configure static NET/ROM routes for specific hosts. The nrparms command enables you to do this. Again, the man page offers a complete description, but a simple example might be:

# /usr/sbin/nrparms -nodes VK2XLZ-10 + #MINTO 120 5 radio VK2SUT-9

This command would set a NET/ROM route to #MINTO:VK2XLZ-10 via a neighbour VK2SUT-9 on my AX.25 port called `radio'.

You can manually create entries for new neighbours using the nrparms command as well. For example:

# /usr/sbin/nrparms -routes radio VK2SUT-9 + 120

This command would create VK2SUT-9 as a NET/ROM neighbour with a quality of 120 and this will be locked and will not be deleted automatically.

== The NET/ROM protocol ==
The original NET/ROM protocol was defined by a company named Software 2000 many years ago for their commercial ROMs for the [[TNC2]]. Later implementations such as by [[The/NET]] were implementing supersets of the protocol.

NET/ROM packets start with a a 5 byte long transport layer folling the [[AX.25]] layer's headers. This header is looking as follows:
<pre>
Offset Use
0 Circuit Index
1 Circuit ID
2 TX Sequence Number
3 RX Sequence Number
4 Opcode and Flags
</pre>
The ''Opcode and Flags'' field is constructed as follows:
<pre>
Bits Use
0 - 3 Opcode
4 Reserviert
5 More Follows Flag
6 NAK Flag
7 Choke
</pre>
NET/ROM implements seven operations for the opcode field. Opcodes 0..6 were already defined in the original Software 2000 NET/ROM specification.
<pre>
0 Protocol Extension
1 Connect Request
2 Connect Acknowledge
3 Disconnect Request
4 Disconnect Acknowledge
5 Information
6 Information Acknowledge
7 Reset
</pre>

=== G8PZT Reset ===
The <tt>Reset</tt> operation was designed by G8PZT. It solves the problem that NET/ROM has nothing equivalent to TCP's RST flag to tell the remote side that a connection does no longer exist on the local side. Strict NET/ROM has no other way of dealing with this case than letting the connection timeout - a <em>very</em> slow recovery method. To avoid reset wars Linux will never reply to a Reset packet with another Reset packet. For paranoia reasons the G8PZT Reset extension is currently disabled by default; it needs to be explcitly enabled by:

<pre>
sysctl -w net.netrom.reset=1
</pre>

The intent is to change the default to enabled after Linux 2.6.17 has been released and no issues have been found.

Help:Editing

2014-06-28T19:18:49Z

VK4MSL: At least provide a link to where the information can be found.

See [http://www.mediawiki.org/wiki/Help:Editing]

Soundmodem

2014-01-11T07:59:54Z

VK4MSL: Not anymore, I have made a mirror

There are two soundmodem drivers for Linux. Linux 2.2 and 2.4 contain a kernel mode driver which requieres a soundblaster compatible soundcard and the soundcard driver will conflict with the soundmodem driver. Also it needs to do digital signal processing - something which is better done in an application than by a kernel driver. For these reasons the kernel soundmodem driver was removed for Linux 2.5.50. No matter what the kernel version the user space driver is prefered. However for completeness sake this article describes the kernel driver as well.

== Configuring the user-mode soundmodem driver ==

Kernel Compile Options: not applicable

Thomas Sailer has written a sound modem driver that runs in user-mode using the kernel sound drivers, so it should work with any sound card supported under Linux.

The driver is implemented as the user-mode program soundmodem. The graphical soundmodemconfig program allows configuring and testing the soundmodem driver. As well as kernel sound support you need the kernel AX.25 mkiss driver.

The software and documentation can be downloaded from http://soundmodem.vk4msl.yi.org/ (mirror of http://www.baycom.org/~tom/ham/soundmodem -- which is now gone).

Detailed instructions and example configurations for debian can be found at http://www.qbjnet.com/packet.html

== Configuring the kernel soundmodem driver ==

This section only applies to Linux 2.2 and 2.4.

Kernel Compile Options:

<pre>
Amateur Radio support --->
[*] Amateur Radio support
--- Packet Radio protocols
<*> Amateur Radio AX.25 Level 2 protocol
...
AX.25 network device drivers --->
--- AX.25 network device drivers
...
<*> Soundcard modem driver
[?] soundmodem support for Soundblaster and compatible cards
[?] soundmodem support for WSS and Crystal cards
[?] soundmodem support for 1200 baud AFSK modulation
[?] soundmodem support for 2400 baud AFSK modulation (7.3728MHz crystal)
[?] soundmodem support for 2400 baud AFSK modulation (8MHz crystal)
[?] soundmodem support for 2666 baud AFSK modulation
[?] soundmodem support for 4800 baud HAPN-1 modulation
[?] soundmodem support for 4800 baud PSK modulation
[?] soundmodem support for 9600 baud FSK G3RUH modulation
...
</pre>

Thomas Sailer has built a driver for the kernel that allows you to use your soundcard as a modem. Connect your radio directly to your soundcard to play packet! Thomas recommends at least a 486DX2/66 if you want to use this software as all of the digital signal processing is done by the main CPU.

The driver currently emulates 1200 bps AFSK, 4800 HAPN and 9600 FSK (G3RUH compatible) modem types. The only sound cards currently supported are SoundBlaster and Windows Sound System Compatible models. If you have a sound card of another type, you can try the user-mode soundmodem described later in this document.

The sound cards require some circuitry to help them drive the Push-To-Talk circuitry, and information on this is available from [http://www.baycom.org/~tom/pcf/ptt_circ/ptt.html Thomas's Soundmodem PTT circuit web page]. There are quite a few possible options, they are: detect the sound output from the soundcard, or use output from a parallel port, serial port or MIDI port. Circuit examples for each of these are on Thomas's site.

The Soundmodem driver creates network devices called: sm0, sm1, sm2 etc when it is configured.

Note

The Soundmodem driver competes for the same resources as the Linux sound driver, so if you wish to use the Soundmodem driver you must ensure that the Linux sound driver is not installed. You can, of course, compile them both as modules and insert and remove them as you wish.

=== Configuring the sound card ===

The Soundmodem driver does not initialize the sound card. The ax25-utils package includes a utility to do this called `setcrystal' that may be used for sound cards based on the Crystal chip set. If you have some other card then you will have to use some other software to initialize it. Its syntax is fairly straightforward:

setcrystal [-w wssio] [-s sbio] [-f synthio] [-i irq] [-d dma] [-c dma2]

So, for example, if you wished to configure a SoundBlaster card at i/o base address 0x388, irq 10 and DMA 1 you would use:

<pre>
# setcrystal -s 0x388 -i 10 -d 1
</pre>

To configure a Window Sound System card at i/o base address 0x534, irq 5, DMA 3 you would use:

<pre>
# setcrystal -w 0x534 -i 5 -d 3
</pre>

The [-f synthio] parameter is the set the synthesizer address, and the [-c dma2] parameter is to set the second DMA channel to allow full duplex operation.

=== Configuring the Soundmodem driver ===

When you have configured the soundcard you need to configure the driver telling it where the sound card is located and what sort of modem you wish it to emulate.

The sethdlc utility allows you to configure the driver with these parameters, or, if you have only one soundcard installed you may specify the parameters on the insmod command line when you load the Soundmodem module.

For example, a simple configuration, with one SoundBlaster soundcard configured as described above emulating a 1200 bps modem:

<pre>
# insmod hdlcdrv
# insmod soundmodem mode="sbc:afsk1200" iobase=0x220 irq=5 dma=1
</pre>

This is not really the preferred way to do it. The sethdlc utility works just as easily with one device as with many.

The sethdlc man page has the full details, but a couple of examples will illustrate the most important aspects of this configuration. The following examples assume you have already loaded the Soundmodem modules using:

<pre>
# insmod hdlcdrv
# insmod soundmodem
</pre>

or that you compiled the kernel with the driver inbuilt.

Configure the driver to support the Windows Sound System card we configured above to emulate a G3RUH 9600 compatible modem as device sm0 using a parallel port at 0x378 to key the Push-To-Talk:

<pre>
# sethdlc -p -i sm0 mode wss:fsk9600 io 0x534 irq 5 dma 3 pario 0x378
</pre>

Configure the driver to support the SoundBlaster card we configured above to emulate a 4800 bps HAPN modem as device sm1 using the serial port located at 0x2f8 to key the Push-To-Talk:

<pre>
# sethdlc -p -i sm1 mode sbc:hapn4800 io 0x388 irq 10 dma 1 serio 0x2f8
</pre>

Configure the driver to support the SoundBlaster card we configured above to emulate a 1200 bps AFSK modem as device sm1 using the serial port located at 0x2f8 to key the Push-To-Talk:

<pre>
# sethdlc -p -i sm1 mode sbc:afsk1200 io 0x388 irq 10 dma 1 serio 0x2f8
</pre>

=== Configuring the AX.25 channel access parameters ===

The AX.25 channel access parameters are the equivalent of the [[KISS]] ppersist, txdelay and slottime type parameters. You use the sethdlc utility for this as well.

Again the sethdlc man page is the source of the most complete information but another example of two won't hurt:

Configure the sm0 device with TxDelay of 100 mS, SlotTime of 50mS, PPersist of 128 and full duplex:

<pre>
# sethdlc -i sm0 -a txd 100 slot 50 ppersist 128 full
</pre>

Note that the timing values are in milliseconds.

=== Setting the audio levels and tuning the driver ===

It is very important that the audio levels be set correctly for any radio based modem to work. This is equally true of the Soundmodem. Thomas has developed some utility programs that make this task easier. They are called smdiag and smmixer.

; smdiag : provides two types of display, either an oscilloscope type display or an eye pattern type display.
: smmixer : allows you to actually adjust the transmit and receive audio levels.

To start the smdiag utility in 'eye' mode for the Soundmodem device sm0 you would use:

<pre>
# smdiag -i sm0 -e
</pre>

To start the smmixer utility for the Soundmodem device sm0 you would use:

<pre>
# smmixer -i sm0
</pre>

=== Configuring the Kernel AX.25 to use the Soundmodem ===

The Soundmodem driver creates standard network devices that the AX.25 Kernel code can use. Configuration is much the same as that for a PI or PacketTwin card.

The first step is to configure the device with an AX.25 callsign. The ifconfig utility may be used to perform this.

<pre>
# /sbin/ifconfig sm0 hw ax25 VK2KTJ-15 up
</pre>

will assign the Soundmodem device sm0 the AX.25 callsign VK2KTJ-15. Alternatively you can use the axparms command, but you still need the ifconfig utility to bring the device up:

<pre>
# ifconfig sm0 up
# axparms -setcall sm0 vk2ktj-15
</pre>

The next step is to create an entry in the /etc/ax25/axports file as you would for any other device. The entry in the axports file is associated with the network device you've configured by the callsign you configure. The entry in the axports file that has the callsign that you configured the Soundmodem device with is the one that will be used to refer to it.

You may then treat the new AX.25 device as you would any other. You can configure it for TCP/IP, add it to ax25d and run NET/ROM or ROSE over it as you please.

Talk:Main Page

2013-03-31T02:54:09Z

VK4MSL: /* linux-mips.org or linux-ax25.org, or perhaps both? */ new section

There is a little mixing of English and German on this page: The word "Protokolls" should be spelled "Protocols".

Thanks,
Scott WA6BLF

Thanks, fixed.

:--Ralf

== linux-mips.org or linux-ax25.org, or perhaps both? ==

2011-11-04 All SSL certificates for linux-ax25.org have been refreshed. As a reminder, linux-ax25.org uses CAcert certificates and the root certificate for CAcert.org (available here is not included with all operating systems and browsers yet so you may have to manually install it if you want to use linux-'''mips'''.org's services encryptedly.

2011-09-07 The recent compromise of a kernel.org servers has resulted in some of kernel.org's servers providing DNS service to linux-'''mips'''.org becoming unavailable. A temporary solution is now in place.

16:18, 21 June 2012‎ DL5RB (Talk | contribs)‎ m (4,797 bytes) (→News: Fix cut and paste error in domain name.)

Evidently, not the only copy-paste error. ;-)

Regards,
--[[User:VK4MSL|VK4MSL]] 02:54, 31 March 2013 (UTC)