Download the bridge program from the link on Johnnys HECnet Page ( It can be run on various Unix operating systems (Linux, OpenBSD, FreeBSD, NetBSD) and Windows (and possibly others!)

The following instructions are for an Ubuntu/Debian installation. Please adapt as required!

Your linux box must have the libpcap and libpcap-dev libraries installed. If you're on ubuntu or debian you can check for these:

dpkg --get-selections | grep pcap

If not installed you can use the synaptic package manager to install both packages using the search phrase 'pcap' or install using apt-get:

sudo apt-get install libpcap0.8 libpcap0.8-dev

If you are using netbsd or another unix variant you can download and compile the source code for the libpcap library from the tcpdump website (

Unpack the bridge source code archive you've downloaded:

msw@x60:~/Downloads$ mkdir bridge
msw@x60:~/Downloads$ cd bridge
msw@x60:~/Downloads/bridge$ tar xvf ../bridge.tar

Check the Makefile and then compile the bridge program by using the make command. If all goes well you will end up with a bridge executable.

The bridge.conf file will need configuring with the remote bridge program to talk to. Johnny will give you the correct information to put in. He will also need to configure his end with your static IP address (or your dynamic hostname - I'm not sure whether this works with a DynDNS)

You should configure the bridge program to start automatically as part of the

operating system boot process. This configuration varies between Unix
implementations, but generally will involve adding a command to */etc/rc.local*
or creating a custom *rc* script.

On my ubuntu box I have the following in */etc/rc.local*:
# Startup the <b >HECnet</b> DECnet bridge
nohup bash /usr/local/bridge/

I've install the *bridge* program and its' configuration file *bridge.conf* into
*/usr/local/bridge* and created the bridge startup script **:
cd /usr/local/bridge
nohup ./bridge 4711 &amp;

The output of the bridge program will go to /usr/local/bridge/nohup.out. Note
the port number 4711 defined as a parameter to bridge. You will need to
configure your ADSL router with a NAT rule to pass traffic from the external
port 4711 (in this example) to the IP address of your Unix box port 4711.

My bridge.conf file has the following custom configuration:

!<name> <ip>:<port>
! or
!<name> <etherdevice>
local eth1

You must select the appropriate ethernet interface to use after local. You can list the configured interfaces using the ifconfig -a command.

NOTE: it is possible to run the hecnet bridge on a Windows box - ask on the hecnet mailing list if this is your best option.

Initial Setup - VMS

You must ensure your machine is setup with DECnet Phase IV rather than DECnet Plus (this simplifies configuration considerably).

Once you've obtained a node name and node number from Johnny you should run the NETCONFIG DCL script from the SYSTEM account to configure DECnet. Note that if you have a large number of machines you may want to run your own area, but this is beyond the scope of my experience.

$ @netconfig
        DECnet for OpenVMS network configuration procedure
This procedure will help you define the parameters needed to get DECnet
running on this machine.  You will be shown the changes before they are
executed, in case you wish to perform them manually.
What do you want your DECnet node name to be?        [BUBBLE]:
What do you want your DECnet address to be?                  : 1.256
Do you want to operate as a router?         [NO (nonrouting)]:
The network object database file is SYS$SYSROOT:[SYSEXE]NETOBJECT.DAT;1.
Do you want to purge the object database?               [YES]:
Do you want a default DECnet account?                    [NO]: yes
Do you want default access to the TASK object disabled? [YES]:
Do you want a default account for the MAIL object?      [YES]:
Do you want a default account for the FAL object?        [NO]: yes
Do you want a default account for the PHONE object?     [YES]:
Do you want a default account for the NML object?       [YES]:

After configuring and starting DECnet you can check the status of your networking with the SHOW NETWORK command:

Product:  DECNET        Node:  BUBBLE               Address(es):  1.256

You then need to copy the latest list of nodes into your node name database. Run the NCP program as SYSTEM:


then execute the following commands:


You can use the command SHOW KNOWN NODES to check whether the database has been updated correctly.

To test that the link is up correctly run a command like DIR MIM:: or DIR BUBBLE::

On VMS you can also test the link using the command MCR NCP SHOW KNOWN CIRCUITS. You should see adjacent nodes, for example:

Known Circuit Volatile Summary as of 22-SEP-2010 22:00:30
   Circuit          State                   Loopback     Adjacent
                                              Name      Routing Node
  ISA-0             on                               11.2 (MAISA)
  ISA-0                                               8.400 (GORVAX)
  ISA-0                                              19.41 (SG1)
  ISA-0                                               1.13 (MIM)
  ISA-0                                               1.15 (PONDUS)
  ISA-0                                               1.300 (CTAKAH)


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posted by Mark Wickens

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