[nos-bbs] SwsVpkt (XP Packet Driver for NOS) update - Installed

Barry Siegfried k2mf at nnj.k2mf.ampr.org
Tue Sep 12 15:53:07 EDT 2006

[wa7nwp <wa7nwp at jnos.org> wrote]:

> I finally installed SwsVpkt driver.  It appears to be almost working.
> First I installed the interface driver system.
> Then, before launching JNOS I ran swsvpkt.bin.
> Loaded jnos.
>    attach packet pkt 0x60 8 1500
>    ifc pkt ip   (same as jnos)
>    ifc pkt netmask 0xffffff00
>    ifc pkt broadcast 0x192.168.27.255
> First step is simply to log in to JNOS from telnet on the local XP-home
> system.  A telnet to launches the BBS on JNOS, but I never
> see text and I have to kill the session.
> I see lots of IP packets in the trace session and what looks to be too
> many checksum errors.
> It's always something.
> Also, it appears all the network traffic the XP box sees is also being
> seen by JNOS.  That's a lot.
> In Linux we use Proxy Arp and route specific packets through the linux
> box to NOS.  We can't do that now with XP?
> Hmmm.  Maybe it is time to consider more Cygwin or DJGPP...
> 73
> Bill - WA7NWP
> PS.  Also sorry to see SwsVpkt has been put on the end of life list at
> their site.

End of life?  LOL  It's a good driver and it works very well.  Well,
just keep what you have because no doubt it will serve you for a long
time to come.

["Steven Stimpson" <steven2 at gwi.net> wrote]:

> I had a problem with sws and XP in I had the same address in the XP
> ip stack and in NOS.

It's important to understand that Steven means he had the same
MAC address because SwsVpkt and the XP drivers are using the same
ethernet card.

> That's a no-no.  XP will reset JNOS connections and vice-versa.

Worse.  JNOS will hear packets which are supposed to go to XP and
try and route them.  You get multiple echos on your LAN wire that
way and it results in a mess.  It makes things unusable.

> It is a good packet sniffer though, interesting to have XP I-net
> activity traced on the NOS screen, you will see some "Interesting"
> things going on behind the scene.
> GL Best 73,
> Steven N1OHX

Like everything else it begged to have a fix and it in fact can be
fixed.  We have discussed this topic on this mailing list before and
unfortunately, I had a disk crash two weeks ago and lost my nos-bbs
archives, so I can't refer back to the original message(s).

Most installations of SwsVpkt will be on the same ethernet card
that that which the hosting Windows O/S IP stack uses.  To make
the JNOS level 2 and ARP drivers play "nicely" with that, you have
to make the following patches in JNOS:

1) In the ethernet receive subroutine (PKTDRVR.C) you need to
   check the source hardware address of each IP frame against
   the interface hardware address in this machine.  If they are
   equal then you must discard the packet and not allow it up
   into the IP layer.  This prevents JNOS's receive IP layer
   from listening to IP packets being sent by the hosting
   Windows O/S onto the LAN and then trying to route them
   to wherever they're going {again}.

2) In the ethernet send subroutine (PKTDRVR.C) you need to
   check the destination hardware address of each IP frame
   against the interface hardware address in this machine.
   If they are equal then you must discard the packet and
   not allow it to be sent into the interface.  Since JNOS
   will hear every IP packet on the LAN that is addressed
   to the hosting Windows O/S this prevents JNOS's send IP
   layer itself from trying to route them to the hosting
   Windows O/S {again}.

3) In the ARP receive subroutine (ARP.C) you need to check
   the source hardware and IP addresses of each ARP frame
   against the interface hardware and IP addresses in this
   machine.  If they are equal then you must discard the
   packet to prevent JNOS from adding its own IP address
   to its ARP list.
The code to do this is relatively trivial and I thought that
at one time Maiko put these additions into the JNOS code.
I can make them available to anyone who wants them.  They
were done for another NOS but with a small bit of editing,
they can be made specific for JNOS.

In any event, while these patches will cause JNOS to "play
nicely" with the hosting Windows O/S using the same ethernet
interface with the same MAC address it does cause JNOS not
to have any IP connectivity with the hosting Windows O/S and
vice versa.  This is a very small price to pay for JNOS being
fully functional as a "stand alone" machine on your LAN in
every other way.

Now, if SwsVpkt had the ability to *change* the MAC address
way Microsoft VPC (virtual PC) does when it uses the same
ethernet interface as that which is used by the hosting
Windows O/S then you wouldn't need the patches above.  But
unfortunately, SwsVpkt doesn't have that capability.

There is, however, another way to avoid having to make the
patches above, and that is to use a technique which VE2PKT
experimented with and perfected.  He added a second ethernet
card to the Windows machine, then UNinstalled the Windows
TCP/IP driver from the second card and installed the SwsVpkt
driver for it.  This gives SwsVpkt (and the JNOS IP stack
running on top of it) its own ethernet interface and MAC
address to use.  There are no patches needed using this
scenario and the hosting Windows O/S will have full IP
connectivity with JNOS (and vice versa), although putting
the patches into JNOS and running it this way (on a seperate
ethernet interface) will do no absolutely no harm.

The bottom line is, it is better to have the patches
installed for those times when the same ethernet interface
will be used as that which is used by the hosting Windows

Hopefully, I've helped you out here, Bill.  And on another
subject, did you happen to look at the directory structure
I posted to the mailing list last week?  Was it of any use
to you?

73, de Barry, K2MF >>
          <|>      Barry Siegfried
| Internet | bgs at mfnos.net              |
| HomePage | http://www.mfnos.net/~bgs  |
| Amprnet  | k2mf at nnj.k2mf.ampr.org     |
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