Anyone have experience with SIMH networking on a Linode?
I'm trying to bring up an emulated operating system (ITS) running under SIMH using the KA10 emulator such that I can access it via TCP from the Linode host, and access the Linode host from ITS.
SIMH does support the tap device, as well as a NAT interface. I'd like to be able to use the tap device interface.
KA10/SIMH supports an emulated IMP (yes, the Interface Message Processor from ARPANET days). And ITS supports the IMP. (I've had great success with the KLH10 emulator running ITS -- because it supports tun, but the KA10/SIMH emulator does not support tun -- only tap).
I believe I need to set up a bridge interface (e.g. br0) between the eth0 NIC and the tap0 NIC. I'm not entirely sure about that, and all my attempts to far have failed. When I create the tap0 device and the br0 bridge and attempt to set up the bridge, I lose all network access to my Linode. I end up having to use the console to login as root and delete the br0 device.
Someone told me that I needed a second IP address (a private IP address would do). I tried adding one (it appears to get added to the eth0 NIC). This didn't seem to help, but I'm not entirely sure I new the proper settings of the IMP SIMH interface in order to make it work properly.
Someone else told me that I needed to set up an alias for my eth0 device, e.g. eth0:1. I tried that too, with no success.
I don't know that much about linux networking, so may have bumbled something. Regardless of the networking environment I've tried, and the values of the IMP parameters I've set in KA10/SIMH, I end up with the guest OS (ITS) running successfully, but no ability to TELNET or SUPDUP into ITS.
Again, I've had no issue doing the exact same thing with KLH10/ITS. In that setup, I can both TELNET in and out of ITS, and use iptables to forward internet traffic in and out. This is exactly what I want to be able to do with KA10/SIMH -- but, as I mentioned earlier, since it only supports tap (and not tun), I don't know what magic I need to do in order to get things working.
I can provide further details if someone here has experience getting tap-based programs to work on Linodes.
1 Reply
rgerke
Linode Staff
I want to preface this by letting you know I have not attempted SIMH networking before, but from the research that I've done to try to give you an answer for this post I've discovered that I want to learn more about it. It's very cool! I'm into retro computing, and this totally relates to my interests.
I can't guarantee this is going to be the solution for you, but I did find a blog post about how to use SIMH with a tap device. Since Linodes are essentially Linux servers, this link should be a good resource:
Networking with SIMH (or QEMU) using TUN/TAP
Here's a git that gives the user's SIMH for KA10:
Since I don't have experience in this myself (yet), I wanted to see what I could find to try to point you in the right direction, and that's what I have come up with. I'm also going to add some tags to this post to give it a bit more visibility so that other users who might have more experience with SIMH/tap are able to find it and contribute.