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How to run Chaosnet

To use Chaosnet, you need to take a few steps.

1. Picking a Chaosnet address

If you are never ever going to connect to the Global Chaosnet (which would be a shame), pick a 16-bit number where both octets are non-zero, and translate it to octal, which is the base used everywhere.

If you might at one point connect to the Global Chaosnet, e.g. to have more communication opportunities, you should contact Björn ( to get an address which work with the rest of the net. Give a brief description of what system or systems you want to connect, and we'll work out the details.

2. Configuring your system

First emulated systems are described, then modern alternatives.

2.1 klh10

A DEC2020 computer - photo by Angelo Papenhoff If you are running ITS using the PDP-10 emulator klh10, things are reasonably easy.

2.1.1 Network configuration

The configuration is done in two parts: the klh10 emulator, and ITS itself. Configure klh10

To use Ethernet as the link layer, use

devdef chaos ub3 ch11 addr=764140 br=6 vec=270 myaddr=XXXX ifmeth=pcap

where XXXX is your Chaosnet address. See “Picking a Chaosnet address”.

To use UDP as the link layer, instead use

devdef chaos ub3 ch11 addr=764140 br=6 vec=270 myaddr=XXXX chip=3040/ Configure ITS

Find your configuration in SYSTEM;CONFIG > at the appropriate IFE MCOND, such as IFE MCOND DB if you are running a vanilla DB system. Make sure to use the following, where XXXX is your Chaosnet address (same as above).

DEFOPT NINDX==50.	;Number of indices
DEFOPT CH11P==1		;CHAOS net goes through Unibus

You might also want to rename your system - see instructions here. DNS configuration

You can of course add hosts to SYSHST;H3TEXT > and run H3MAKE, but you can also use DNS in ITS. It's a bit of a mess right now, I'll document it later.

2.2 LambdaDelta

An LMI Lambda LambdaDelta uses the Ethernet link layer. The configuration is done entirely in the lisp system.

2.2.1 Network configuration

Edit SYS:SITE;HOSTS TEXT to change the CHAOS address of your host. 1)

Use (make-system :site :compile :noload :noconfirm :no-reload-system-declaration) to recompile the site configuration, including the host table.

Use (UPDATE-SITE-CONFIGURATION-INFO) to load the updated site configuration, including the host table.

2.2.2 DNS configuration

You need to use SYS:SITE;HOSTS TEXT for your local address, but if you don't want to add other hosts manually, you can use DNS.

Edit SYS:SITE;SITE LISP to set the appropriate site options. Suggestions:

Site option Value Explanation
:DOMAIN-CHAOSNET-P T Enable using DNS for Chaosnet addresses
:CHAOS-ADDRESS-DOMAIN “CH-ADDR.NET.” The address domain for the global Chaosnet
:DOMAIN-CHAOS-SERVERS '(“”) The DNS server at Update Computer Club, which knows Chaosnet data

Use (make-system :site :compile :noload :noconfirm :no-reload-system-declaration) to recompile the site configuration.

Use (UPDATE-SITE-CONFIGURATION-INFO) to load the updated site configuration.

2.3 usim/CADR

A CADR Lisp machine usim uses unix sockets for link layer. Depending on your version, you might need to edit the code to change your address, but perhaps you can use a command line option. You also need to run chaosd.

2.3.1 Network configuration

See “Network configuration” for LambdaDelta (note: there is no DNS support in the CADR system).

2.4 Linux/Unix/macOS

The Chaosnet bridge program, cbridge, can use any link layer, depending on your needs (see above).

2.4.1 Network configuration

2.4.2 DNS configuration

See, the dns option. If you use LambdaDelta, you can turn on the forwarder option and add the Chaosnet address of cbridge to :DOMAIN-CHAOS-SERVERS (see above) as an octal number.

2.4.3 Application programming

See No really, I should add stuff here. But see the example programs

For a quick test, you can also (setq chaos:my-address #oXXXX chaos:my-subnet #oYY) where XXXX is your address, and YY is your subnet, i.e. the highest 8 bits of your address.
running.txt · Last modified: 2021-04-01 11:41 by victor