[Simh] simh and tap device under linux

[Mark Abene]

I've been running 2.11BSD and RSTS/E v8 for several years in two
separate simh instances using multiple tap interfaces on the same
server.  What "support" do you think simh is lacking?

set xq type=delqa
set xq mac=08-00-2B-C0-12-34
attach xq tap0

...works just fine.


Andrew Warkentin wrote:
> Seth Morabito wrote:
>> On Tue, Aug 25, 2009 at 10:45 AM, Tim Newsham<newsham at lava.net> wrote:
>>   
>>>> The other technique works as long as you have 'sudo' installed. You
>>>> can add a line to your /etc/sudoers file to let a normal user (login
>>>> 'foobar') run the executable as root:
>>>>
>>>> foobar           ALL=NOPASSWD: /path/to/pdp11
>>>>       
>>> You might as well just give root access to the person who will
>>> run pdp11.  If its setuid you can just shell out and run
>>> commands as root:
>>>     
>> Good point - I was totally unaware that the ! command existed in SIMH
>> and allowed shell access. So both of those techniques are no good.
>> I've never had any reason to allow anyone (but myself) to run SIMH, so
>> I guess we're back at square one.
>>
>> FWIW, I've been toying with creating a small JEOS VMware virtual
>> machine for SIMH, but it suffers a related problem: VMware will
>> complain if you attempt to put a guest ethernet device in promiscuous
>> mode. The host needs special permissions set on the /dev/vmnet*
>> interfaces for it to work, so it's not a drop-in solution either.
>>
>> A purely user-space networking solution for SIMH is badly needed
>> (well, for some definitions of 'badly'.  And 'needed'. But it would
>> certainly be very welcome.)
>>
>> -Seth
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>>   
> There is a patch that replaces the libpcap-based network support with 
> SLiRP. It is IP-only, and the only way to run servers on it is to 
> redirect specific guest ports to host ports (these kinds of restrictions 
> will affect just about any userspace network stack).
> Maybe SIMH should have support for using /dev/tap* or /dev/net/tun like 
> e.g. Hercules does. That would get around both the problem of having to 
> run the simulator as root, and the inability of the guest to talk to the 
> host, while still allowing the guest to be fully accessible from the 
> outside and use non-IP protocols.
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