LinuxSA Mailing list archives

  From: Glen Turner <glen.turner@aarnet.edu.au>
  To  : 
  Date: Thu, 27 Jan 2000 20:10:21 +1030

Re: Linux as an NT Server replacement

Sean Burford wrote:
> 
> > 5 Email (MS Mail/Exchange/Notes/etc -- are these particularly different to
> > POP/IMAP/SMTP? Do they do anything Linux mail can't do?)
> 
> Investigate LDAP.  Exchange has handy global addressbook features, and
> integration with scheduling (Outlook).  I have not seen these supplied under
> Unix.  Find out if your users require this functionality, and what the
> alternatives are.

Netscape's Calendar client runs on Linux (I'm using it now).  The backend
runs on UNIX(tm) and a Linux port has been promised.

LDAP works well, and is better than AD as you can also run your
Samba, Apache and PAM authentication against it for a single
password environment.  In Linux 2.2 you do have to watch
the user count -- the limit is 16000 users (ie: not enough
to put every uni student into LDAP and authenticate from there).
Linux 2.4 will allow about a billion users, and the code has been
tested with 160,000 real user entries in LDAP.

The Notes Domino server is available for Linux and runs fine.  The Notes
client is being phased out anyway (in favour of the generic web browser).

You can't configure both IMAP and Exchange simultaneously in Outlook.
This is a pain, as you need to cut over rather than migrate when
moving from Exchange's secret protocol to IMAP.

I'd recommend the Cryus IMAP server over the default Washington
Uni IMAP server.  Cryus IMAP has shared folders (good for generic
addresses like inquiries@aarnet.edu.au) and allows multiple clients
to access a folder simultaneously.  This is handy if you want to
read your mail from multiple machines.  Cyrus works fine with Outlook,
Communicator and Pine.


Richard Russell wrote:
>
> 7 PostgreSQL/MySQL should be almost equivalent, although a simple swap may
> not be possible -- any comments?

MS "SecretServer" is more advanced than Postgres or MySQL and less advanced
than Oracle or DB2.  You're best off letting your application's robustness
and transaction rate requirements drive the choice of database.

Unfortunately, database SQL needs some porting to move between vendors.
Worse, some application use proprietary server-side languages.
And if there is a transaction rate worth considering, you'll also have
to redesign the I/O subsystem on your server, as differing databases
have differing I/O access patterns.


> 8 DNS standard

The ISC DNS is much better than the MS version.

Depending on your client computers, you may need to install both
DHCP and DNS and do DNS Dynamic Updates.  Rumour is that Win2000
pretty much needs this in a corporate environment.


Daryl Tester wrote:
>
> Active Directory is, I think, Microsoft's rebadging of LDAP.  I wonder
> what they think a "Passive Whatever(TM)" is (probably a blue-screened
> NT box)?

Unfortunately not.  Microsoft's directory model varies significantly
from the LDAP model.  MS namespaces aren't really heirarchical, for
one.  AD will use LDAP as a replication mechanism.  So suppossedly,
you can change attributes in NDS and they will update in AD via LDAP.
This sort of gatewaying has always been trouble, and you'd want to
test it well before relying on it to work.

The Win2000 authentication environment is also a disaster zone.  I
think Richard is reverse engineering this for Samba right now.


The summary is that Linux *can* do most the things an NT Server will.
What you have to decide is if, having made an investment in MS products,
training and learning curve, you can ditch your MS investment and install
Linux and still save money.