HP-UX B.10.20 A 9000/777 netmask 255.255.255.248 fails

[Kevin R. Bulgrien]

The forums contain various references to this problem - in particular for HP-UX 11. In most cases, the reply suggests a solution like:

> Try disabling subnet mask checking:
>
> ndd -set /dev/ip ip_check_subnet_addr 0
>
> To make permanent,
> edit /etc/rc.config.d/nddconf:
>
> TRANSPORT_NAME[0]=ip
> NDD_NAME[0]=ip_check_subnet_addr
> NDD_VALUE[0]=0

However, there is no /etc/rc.config.d/nddconf, and further, ndd is not found on my system.

$ whoami
root

$ ndd
ksh: ndd: not found

$ find /usr -name ndd

$ find /bin -name ndd

$ find /sbin -name ndd

$

Editing netconf to include the above variable assignments also does not work.

The applicable section of netconf is:

IP_ADDRESS[0]=192.168.127.3
SUBNET_MASK[0]=255.255.255.248
INTERFACE_NAME[0]=lan0
BROADCAST_ADDRESS[0]=192.168.127.7
LANCONFIG_ARGS[0]="ether"
DHCP_ENABLE[0]=0

This configuration works fine on other operating systems on that network, but will not work on this HP-UX system.

The message returned is:

$ /sbin/init.d/net start
ERROR: lan0 interface: ifconfig: ioctl (SIOCSIFADDR): Can't assign requested address

Upon further searching, I see a statement:

> According to subnet RFC (RFC 917 and others)
> The first subnet and the last subnet cannot > be used.

This and associated commentary appears to imply that I should not attempt use addresses 192.168.127.1 though 192.168.127.7 if I read them correctly. It this really true, and if so, why do other systems allow this?

By this logic, one should not use 192.168.0.x/24 addresses, but I have seen this done all the time, even in commercial products like DSL modems and/or broadband routers.

I am not sure what to do to get the system properly configured.

The problem is that I have been assigned 192.168.127.0/24, but have run into a situation where I want to split my assigned addresses into two routing domains to solve a particular problem.

Presently, the whole thing works fine if I set the HP system to use a 255.255.255.0 netmask because it currently has no need to talk to the rest of the 192.168.127.x addresses in the "other" routing domain, but it seems more proper to set the netmask and broadcast to reflect the actual network architecture to avoid problems if the system ever does need to talk to those addresses.

[Denver Osborn]

This reply won't help you out too much, but I wanted to note that ndd was not on 10.20. You'd use nettune, but I can't say for certain if you'd be able to set ip_check_subnet_addr 0 on 10.20 using /usr/contrib/bin/nettune.

-denver

[Sameer_Nirmal]

Hi,

I would have the latest ARPA patch on the system.
I believe there is no need to turn off the subnet checking as subnet mask is set correctly and there is no viaolation of RFC1122.

You can try turning off the broadcast address checking using nettune command. I am not sure , but you can check the man page of nettune.
# nettune -s check_bcast_addr 0

If above does not work then adb could be used to turn off the broadcast checking.

[Jim Keeble · Accepted solution]

See Doc ID NETUXKBRC00008098 .

The nettune parameter is ip_check_subnet_addr

Your ARPA transport patch has to be PHNE_14504 or higher.

The command to turn it off is :

nettune -s ip_check_subnet_addr 0

And you need to create an rc script to make it "permanent".

[Kevin R. Bulgrien]

I have no idea how to get documents by document ID number as I tried all the search forms I could find on the HP site to no avail. Fortunately, Googling got me this link:

http://www1.itrc.hp.com/service/cki/docDisplay.do?docLocale=en_US&docId=200000062912284

[Kevin R. Bulgrien]

Woohoo Jim... You got a hat now.

/etc/rc.config.d/netconf now has:

/usr/contrib/bin/nettune -s ip_check_subnet_addr 0

IP_ADDRESS[0]=192.168.127.3
SUBNET_MASK[0]=255.255.255.248
INTERFACE_NAME[0]=lan0
BROADCAST_ADDRESS[0]=192.168.127.7
LANCONFIG_ARGS[0]="ether"
DHCP_ENABLE[0]=0

Everything works as expected.

[Kevin R. Bulgrien]

All three respondents hit the nail on the head for 10.20. nettune was the missing link for me.