Adding multiple PCnet NIC’s to a Windows NT 4.0 Terminal server under Qemu

So this is probably nothing that exciting for most people, but for me, I wanted to have a Terminal Server onto a DECnet network. Sure I could have probably just done one nice with tun/tap, dumped all the protocols on there, and called it even. But for some reason I wanted 2 NICs to keep the IP on one side, and DECnet on the other.

One thing I wanted was an internal bridge for DECnet only traffic, and since I just need MSRDP access, SLiRP can handle a single TCP port redirect.

The flags are as always pretty simple once you work them out:

qemu -vga std -cpu pentium -m 384 -vnc :0 -net none \
-hda nt4tse.vmdk \
-device pcnet,netdev=slback \
-device pcnet,netdev=decback \
-netdev tap,ifname=tap1,id=decback,script=/root/nt4tse-up,downscript=/root/nt4tse-down \
-netdev user,id=slback,hostfwd=tcp::3389- \
-cdrom Windows\ NT\ 4\ All-In-One\ (Workstation\,\ Server\,\ Terminal\,\ Enterprise).iso

And the two network scripts starting with nt4tse-up:

echo starting $1
ip tuntap add mode tap tap1
ifconfig tap1 up
ifconfig tap1
brctl addif decnet0 tap1
brctl show decnet0
echo done with tuntap

And the nt4tse-down:

echo shutting down $1
ifconfig tap1 down
brctl delif decnet0 tap1
brctl show decnet0
ip tuntap del mode tap tap1
echo done shutting down $1

for completeness here is the bridge config in /etc/netplan/50-cloud-init.yaml

            - SOMETHING/24
            gateway4: SOMETHING
                macaddress: 00:f4:c1:56:40:7e
        dhcp4: no
        addresses: []
        dhcp4: no
    version: 2

This way I have an IP bound bridge for things that talk IP, and a raw bridge, decnet0 that has my non IP decnet stuff on there. Naturally it’ll have my SIMH VAX on there:

# brctl show decnet0
bridge name     bridge id               STP enabled     interfaces
decnet0         8000.aede9f227e7b       no              tap0

Also the ability to mount directories as fake fat drives had it’s syntax change as well

 -drive file=fat:rw:win95cd

into something like this:

-drive file=fat:rw:dos,id=fat32,format=raw,if=none -device ide-hd,drive=fat32

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.