HP-UX 11.0 routing issue

[Nyck_1]

I have an HP-UX11.0 server in our Madrid office that can comunicate with all the other servers in the office but it cannot comunicate with any of the servers in other offices. This server was working fine until yesterday and as far as i'm aware nothing has changed on it.

I have checked the default route and nothing is wrong with that. But when i remove the route and then re-add it the server will comunicate with the outside world but for only about 2 mins!

Has anyone come across this issue and if so how was it resolved?

[Bill Hassell · Accepted solution]

Actually, something has changed. Most likely, your network administrator changed the Madrid office's router to ignore ping requests. This is a fairly common security change for a firewall's external interface but for internal networks, it is a very poor choice. It causes the dead gateway detection feature in HP-UX to turn off the route. That means that only the local subnet is accessible. Check if the this true:

ndd -get /dev/tcp ip_ire_gw_probe

If it is 1, check if the gateway is disabled:

ndd -get /dev/ip ip_ire_status | grep -e IRE_GATEWAY -e flag

If true, turn off this feature:

ndd -set /dev/tcp ip_ire_gw_probe 1

Then make the change permanent by editing the file /etc/rc.config.d/nddconf:

TRANSPORT_NAME[2]=ip
NDD_NAME[2]=ip_ire_gw_probe
NDD_VALUE[2]=0

(pick the next unused array element in this file such as [2] or [3]). Note also that for 11.00, early versions of ndd had a bug that prevented the changes in nddconf from taking effect. Get the latest ndd patch. Test success with ndd -c to read the nddconf file as it does during a reboot.

As a note, disabling ping response (aka, ICMP Echo Request) on a firewall's external interface is quite normal and an accepted practice, but turning this feature off for internal routers does not make a lot of sense.

[Nyck_1]

hello,

I had just spoken to our network administrator and yup the change was made yesterday hence this issue!

So i have made the change that you spoke about and all seems fine.

Thanks very much!