SUMMARY: Netmask issue on SunOS ... 4.1.1!

From: Peter Laws <>
Date: Fri Apr 25 2008 - 10:56:58 EDT

Best answer was from Matthew Stier (below) right out of the FAQ 
I should have consulted in the first place.  Several others had the goods, 
too, including a fellow admin here.  THANKS TO ALL of you for your rapid 

Many folks believed that SunOS 4.x can not deal with VLSM.  Not true!  And 
it *can* be set in /etc/netmasks (some suggested hardwiring in rc.local).

The trick is that you list the Class B network number (no trailing zeros) 
and then the netmask.

Don't try to out-think it like I did and put in the full network number.  I 
deleted the 3rd octet from /etc/netmasks, rebooted, and all was well.

One caveat for 4.1.1, at least without patches:  ifconfig will show the 
Olde Style broadcast address, i.e. the all-zeroes version, not the all-ones 
version.  Yep, looks just like the network number.

Works OK though and I'm now sharing data from the massive 1000 MB external 
disk to the net.  :-)

Many thanks, all!


From: Matthew Stier
To: Laws, Peter C. <>

3.8: How to Set a Netmask under SunOS

In order to include a permanent netmask on your SunOS machine, you must
make an entry in the /etc/netmasks file, in the following format:
network-address-without-zeroes netmask For example: %%%% cat
/etc/netmasks 150.101 The above would subnet the class B
network,, into 254 subnets, from to It is important to note that the entry in the left hand
column must be the original base network number (ie # for a Class A, #.#
for a Class B and #.#.# for a Class C), not the subnet.

Peter Laws wrote:
> First, I can't believe I'm back here after all these years.  Is Casper D
> still lurking?   :-)
> Anyway, I'm helping out (read: one of the few that's ever seen an SS2) with
> a SPARCstation 2 connected to an Acoustic Scanning Microscope.   It runs
> 4.1.1 (unpatched, AFAIK) and the folks that own it have a burning desire to
> share out its disk on the network.
> Yes, I warned them.
> Yes, I commented out most stuff in inetd.conf.
> Yes, we found a transceiver.  :-)
> Anyway, address is on a /21 network.  I think I have the right stuff in
> /etc/netmasks, but when it reboots, I get a /16 (our address block really
> is an old Class B).
> Ideas?
> I'll summarize (like anyone would care! :-)
> Thanks!

Peter Laws / N5UWY
National Weather Center / Network Operations Center
University of Oklahoma Information Technology
Feedback? Contact my director, Craig Cochell, Thank you!

[demime 1.01b removed an attachment of type text/x-vcard which had a name of plaws.vcf]
sunmanagers mailing list
Received on Fri Apr 25 10:57:46 2008

This archive was generated by hypermail 2.1.8 : Thu Mar 03 2016 - 06:44:10 EST