Network logon when using Windows Dial-up Networking and Samba

[Richard Sharpe]

Between us, Andrew and I have discovered the problem with Windows 95
Dial-Up Networking (DUN) access via PPP to a Samba server.

The following shows where the last problem is.

>Date: Sun, 26 Apr 1998 15:10:01 +1000
>From: Andrew Tridgell <tridge at samba.anu.edu.au>
>Subject: Re: Network logon when using Windows Dial-up Networking and Samba
>Sender: Andrew Tridgell <tridge at samba.anu.edu.au>
>To: sharpe at ns.aus.com
>Cc: paulus at cs.anu.edu.au
>Reply-to: tridge at samba.anu.edu.au
>
>> >well, it is also possible that the WINS1 and WINS2 defines are the
>> >wrong way around in the pppd header files. 
>> 
>> Bingo ...
>> 
>> >From ipcp.h
>> 
>> #define CI_MS_WINS1     128     /* Primary WINS value */
>> #define CI_MS_DNS1      129     /* Primary DNS value */
>> #define CI_MS_WINS2     130     /* Secondary WINS value */
>> #define CI_MS_DNS2      131     /* Secondary DNS value */    
>> 
>> >From RFC1877
>> 
>> Primary    DNS = 129
>> Primary   NBNS = 130
>> Secondary  DNS = 131
>> Secondary NBNS = 132
>> 
>> Thus Primary and Secondary DNS Will work, but a Primary WINS from Win95
>> will look like a Secondary WINS to ppp, while a Primary WINS will be
>> confused as something else, perhaps an ADDR request by the look of the
>> trace ...
>
>ahh, great. 
>
>Paul, you got that?
>
>Cheers, Andrew

Now the background.  If you have subnetted your network, then Win 95 PPP
gets things wrong. It ignores, or does not ask for, the netmask for your
network, and sets a netmask appropriate to the class of address it is given
for the link.

So, if it is given an address of 172.16.8.160, it sets the netmask to
255.255.0.0, even if you are using a netmask of 255.255.252.0 :-(

This screws up broadcast based name service lookup, like NetBIOS Name
Resolution, so you cannot logon to an SMB server via PPP using simple
broadcast name resolution.  You have to use WINS.

Well and good, and Win 95 DUN can request both a primary and secondary WINS
server.  Unfortuantely, ppp 2.3.3 (and most likely many versions prior to
that) has a bug (as shown above) where if you only define a primary WINS
server, name resolution does not work because Win 95 PPP does not get a
WINS server address.

This problem has been brought to the attention of Paul MacKerras and Al
Longyear, so a patch will be forthcoming, but it is likely to pervade the
free PPP versions out there and even reach into places like Digital's PPP
for Digital UNIX, since they based their work on the PPP code that Paul
developed with others.

The work-around is to specify two ms-wins entries in the PPP options file, eg:

  ms-wins a.b.c.d
  ms-wins a.b.c.d

Only the second is relevant, and should be the IP address of your primary
WINS server.



Regards
-------
Richard Sharpe, sharpe at ns.aus.com, NIC-Handle:RJS96
NS Computer Software and Services P/L, 
Ph: +61-8-8281-0063, FAX: +61-8-8250-2080, 
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