[Simh] Problem with "attach xq"

[Hittner, David T.]

If you look at the attach code, you'll see that *some* of the real pcap-selectable adapters are
'disallowed' and removed from the list of connectable devices if they do not meet
certain criteria - this was primarily done to remove WAN adapters, bridges (brX), loopbacks (lo0)
and similar 'illegal' network objects from the list. And yes, this can make it a bit confusing.

The reason for the 'ATT XQ ethX' syntax is that the code was originally designed using a
simple linux system with just the standard eth0 port, and the pcap map-numbered syntax
was added later to 'standardize' the attach syntax for Windows systems (which have horrible device names).

However, for MOST users on systems with one or two ethernet ports, the ethX designation will work -
if not, you can either
  1) Get the list of allowed devices with SHOW XQ ETH (as Mark suggested), or
  2) Connect using the hard device name with ATT XQ <device-name-literal>
	(on *ix use the full path of the device, not the just the simple ethX designator)
      [this also works to 'force' connection to one of the illegal devices]

The pattern 'ethX' is what triggers the PCAP filtered map correlation - if the device
string does not match the 'ethX' 4-character pattern, it will assume
that you are using a device-name-literal. I suppose that we could 
disambiguate it by making the match pattern 'pcapX', however that
would *still* confuse people who have run tcpdump and are expecting the full list
of pcap device numbers, not just the 'allowed' list.

We would be happy for anyone familiar with *ix device programming to provide
the code to fill in the device description string to help make it more obvious
which adapter you are selecting.
      
Dave
SIMH Ethernet developer

> -----Original Message-----
> From: simh-bounces at trailing-edge.com 
> [mailto:simh-bounces at trailing-edge.com] On Behalf Of Jan-Benedict Glaw
> Sent: Thursday, January 24, 2008 5:08 AM
> To: Vorländer, Martin
> Cc: simh at trailing-edge.com
> Subject: Re: [Simh] Problem with "attach xq"
> 
> On Thu, 2008-01-24 10:33:13 +0100, Vorländer, Martin 
> <MV at PDV-SYSTEME.DE> wrote:
> > > Jan-Benedict Glaw wrote:
> > > sim> sh xq eth
> > > ETH devices:
> > >   0  eth1 (No description available)
> > >   1  eth2 (No description available)
> > > 
> > > > The "N" in the "ethN" of the "attach xq ethN" simulator command 
> > > > corresponds to the number under the "ETH" word in the output of 
> > > > the "show xq eth".  The "eth#" value in the "show xq 
> eth" output 
> > > > is the OS device name.  They might NOT be one to one related.
> > > 
> > > Argh!  This is somewhat misleading, isn't it? But thanks anyways, 
> > > I'll test that.
> > 
> > Under Windows it is a bit more descriptive:
> > 
> > C:\> vax.exe
> > 
> > VAX simulator V3.7-3
> > sim> show xq eth
> > WinPcap version 4.0.2 (packet.dll version 4.0.0.1040), based on 
> > libpcap version 0.9.5 ETH devices:
> >   0  \Device\NPF_GenericDialupAdapter                   
> (Adapter for generic dialup and VPN capture)
> >   1  \Device\NPF_{352FF5EC-F252-4F57-9B7D-9136E1641658} 
> > (LAN-Verbindung)
> > sim>
> > 
> > I have no idea whether some description could be fetched by 
> the code 
> > on *ix systems, too.
> 
> The point is that attaching to "ethX" is misleading, 
> specifically when the OS is Linux where the devices are also 
> called "ethX". So in the Windows case, I'd intuitively type 
> "\Device\NPF_{35....}", but not "eth1".
> 
> MfG, JBG
> 
> -- 
>       Jan-Benedict Glaw      jbglaw at lug-owl.de              
> +49-172-7608481
> Signature of:         Alles wird gut! ...und heute wirds 
> schon ein bißchen besser.
> the second  :
>