Subnet conf. on HPUX 11.0

[Martial Gourde]

I have a B2000 with one NIC and I tried to specified a netmask with a subnet (2 segments). I also tried to set the BROADCAST accordingly and the result is in CDE unable to start. If I do not specify the subnet then everything goes on except that I am unable to access Internet and other subnets.

The IP addresses are class 'C'.

[harry d brown jr]

Please post the IP, subnet mask, and broadcast addr you were trying to setup.

live free or die
harry

[eran maor]

Hi

you can define your ip and netmask in the /etc/rc.config.d/netconf file .

you can also provide the default getway in this file .

you can also do it with SAM ( you can active acsi mode of sam )

[Martial Gourde]

The station IP is 205.236.244.7.
The netmask is 255.255.255.128.
The broadcast is 205.236.244.127.

I used SAM, set_parms and also manually modified netconf. Still no success.

NOTE: using SAM and set_parms returns an error stating that the subnet mask is invalid.

To get the system to partially work the defaults are used (netmask= 255.255.255.0).

[Bill Hassell]

Correct. The subnet mask is too small for the default subnet mask rules. For small subnets, you need to change to use the more modern subnet mask rules by using ndd as in:

ndd -set /dev/ip ip_check_subnet_addr 0

Now the rules will handle smaller subnets. To make this change permanent, edit the file: /etc/rc.config.d/ndd and include this parameter (ip_check_subnet_addr) and value (0).

[Martial Gourde]

The changes to ndd fixed the boot errors and the CDE problem.

Now I back to my main problem that is for a small period of time after the fresh startup I can 'traceroute' remote machines (like www.hp.com) and use NETSCAPE, but after 1 minute or less of activities I get Network Unreachable errors. This also occurs for machines on the other subnet portion.

Any idea?

[Ron Kinner]

Believe 11.0 has a feature which checks to see if your gateway is alive by pinging it. Perhaps your gateway is a bit paranoid and doesn't want to reply to pings so the gateway timeout applies and the system thinks you no longer have a gateway?

Can you ping your gateway right after a reboot? Can you still ping it after a few minutes?

Do a
netstat -rn
right after a reboot and then later after it starts working and compare.

Try your trace using the IP address instead of the name and see if that works better. Might be a problem with the DNS but I suspect it's a gateway issue.

Ron

[Martial Gourde]

1) TRUE the gateway does not accept 'pings'. It is working for all other systems.

2) I can not ping the gateway immediatly after reboot but the packets goes through.

3) Traceroute works from boot time up to 1 minute approx.

4) Using host name or IP give the same result.

5) netstat shows no changes before and after. The routing table is very limitted: loopback, host and default.

6) The DNS server is on the gateway system and is still accessible after the Network Unreachable error.

[Ron Kinner · Accepted solution]

OK. You have the Dead Gateway detection problem:

HP-UX 11.0 introduces the "Dead Gateway Detection" feature. Network connections hang after varying intervals. The "Dead Gateway Detection" feature sends ICMP echo requests (ping packets) to all gateways. As UNIX 11.X enables "dead gateway detection" as a default, when you block icmp packets, after a while the system assumes your gateway is dead and doesn't use it anymore.
To find out if the gateway is "dead":

#ndd -get /dev/ip ip_ire_status | grep -e IRE_GATEWAY -e flag
If the output for default route says "IRE_GATEWAY_DEAD", then there is a dead gateway problem. To fix this problem, use ndd to disable ip_ire_gw_probe to 0.

To disable dead gateway detection using ndd:
To get the current value:

#ndd -get /dev/ip ip_ire_gw_probe
To set it to zero:

#ndd -set /dev/ip ip_ire_gw_probe 0

http://people.hp.se/stevesk/bastion11.html tells how to set this and other ndd options at boot. Otherwise ndd changes go away after a boot.

Ron

[Martial Gourde]

Great. Thank you.
The changes worked very well.

Also thank you for the link to the document. Good stuff in.