topic Subnetmask problem in Operating System - HP-UX

Subnetmask problem

Linda Card — Fri, 10 Jun 2005 15:08:57 GMT

I just had a scenario where a site got a new firewall and decided to subnet into 2 network (?) and used a subnetmask of .128 to have two subnets. My old hpux 10.20 box gave me "red" in the rc during bootup but I got a login window. When I logged in, it hung and I eventually (10 minutes later) got "Unable to initialize or connect to the Desktop messaging system. Check your $HOME/.dt/errorlog". I booted Single User and the errorlog had "Tool Talk session could not be started". These errors were meaningless to me.
So I read the /etc/rc.log and saw the "red" during bootup was for /sbin/rc2.d/S008net start and had "lan interface: ifconfig: ioctl Can't assign a requested address. Service failed."

I heard from another sysadmin that my application will not work on a 2-subnet network because it doesn't like being in all-zero or all-1s subnetworks.
I heard from another source that this is true only on older routers. So I disconnected my HP box from the network, changed my subnet mask to .128 using set_parms addl_netwrk and rebooted. So the HP box never makes it to the router, it should boot up, right? No go. I got the same hang and error.
I know this is old stuff but can somebody explain why .128 subnets don't work on my HPs?
Thank you,
Linda

Re: Subnetmask problem

D Block 2 — Fri, 10 Jun 2005 15:26:38 GMT

Linda,

what about your default gate-way subnet mask and the IP subnet mask defined in the:
/etc/rc.config.d/netconf

I'll assume set_parms did the correct update in this file, but pls check it for it is used during the reboot. sounds like it might be the default gw's netmask setting in this file.

Re: Subnetmask problem

Steven E. Protter — Fri, 10 Jun 2005 19:15:48 GMT

Hi Linda,

When the network folks subdivided the network, they should have provided you with the subnet mask and anything else, like default gateway that has changed.

There is nothing inherent in dividing the network that should have cut you off from the old gateway, unless it was part of the other half of the network that was just divided.

Network Administration needs to brief you on the new addresses, if they even took your access into consideration in doing their divide the network plan.

Usually when this is done, servers are put all together in their own small collision domain. I can not be sure, but I smell some bad planning here. Not you though.

SEP

Re: Subnetmask problem

D Block 2 — Fri, 10 Jun 2005 19:34:02 GMT

you mention, that; "So I disconnected my HP box from the network, changed my subnet mask to .128 using set_parms addl_netwrk and rebooted".

I heard that the 10.20 version is not graceful when pulling the network cable out, that the kernel tries to reconnect using a high-priority interrupt, and just may hang your system in a loop.

load 11.11 or 11v1.

Re: Subnetmask problem

Ermin Borovac — Sat, 11 Jun 2005 00:39:00 GMT

RFC 1122 disallows all-zero subnets. Your IP address probably contains all zeros in subnet field. To turn off this behaviour run

# nettune -s ip_check_subnet_addr 0
# /sbin/init.d/net start

Re: Subnetmask problem

Devesh Pant_1 — Sat, 11 Jun 2005 00:50:53 GMT

Linda,
you might want to jot down clearly
1. The IP address
2. The subnet mask
3. The default gateway

Since you have subnetted your original network into two the subnet mask will change and so will the default gateway.

Please make sure whoever is involved in this network stuff provides you the right info.

Also I am assuming you have only one NIC if you have more than one nic and the cable is not plugged into the primary NIC, set_parms is not the right way.
Please figure out the lan0 or lan1 using the commands
ioscan -funC lan
also use the lanscan and netstat -in
and then edit the files /etc/rc.config.d/netconf with the correct values for the following
IP_ADDRESS
SUBNET_MASK
INTERFACE_NAME
BROADCAST_ADDRESS
and then do the
/sbin/init.d/net stop
and then a
/sbin/init.d/net start
or alternatively you may reboot

thanks
Devesh

Re: Subnetmask problem

Linda Card — Tue, 14 Jun 2005 14:36:47 GMT

Thank you to all. I got some great answers. I will put these ideas in my toolbox for later use.

The site was reluctant to put my HP behind the firewall because of the ports they would have to open to enable my apps on the HP.

So outside the firewall I went and I tested all variations of the subnetmask. It does not like first and last subnet, whether it is 2 subs or 8 subs. I changed the mask to .0 and all is well. I just have to remember this for next time.
Thanks for the help.