topic Re: Network Unreachable in Operating System - HP-UX

Network Unreachable

Timothy P. Jackson — Fri, 01 Apr 2005 00:35:04 GMT

I am trying to get my sendmail to relay through my exchange server which is on a totally different network. My HP-UX machine is on the same network as my MS machines and they are sending and recieving mail just fine. My exchange server is also an ftp server. I can ftp to this server from any of my MS machines but I cannot ftp to it from my Unix box. I get the same message that sendmail gives me.

My ftp server IP is 24.123.113.82

My HP-UX server IP is 192.168.101.8

My default gateway is 192.168.101.1

I cannot ping this server because it set to not accept ping. I can do a nslookup on this server and it works great from the HP-UX server.

Any Help would be greatly appreciated!

Tim

Re: Network Unreachable

Muthukumar_5 — Fri, 01 Apr 2005 01:26:45 GMT

what is your hostname resolvation entry in your hp-ux machine as,

/etc/nsswitch.conf
/etc/resolv.conf
/etc/hosts entry

IS your route entries are being fine?

Re: Network Unreachable

Timothy P. Jackson — Fri, 01 Apr 2005 01:38:06 GMT

You won't believe this...

It suddenly started working. I could ping www.yahoo.com, my sendmail was working and the ftp was working.

Then....

It stopped working!

I rebooted my firewall/default gateway and then it was working again but only for a couple of minutes.

I wonder if my firewall is where the problem is?

Re: Network Unreachable

Bharat Katkar — Fri, 01 Apr 2005 01:39:26 GMT

Hi Tim,
Does ur netstat -rn output look like this:

Destination Gateway Flags Refs Interface Pmtu
127.0.0.1 127.0.0.1 UH 0 lo0 4136
192.168.101.8 192.168.101.8 UH 0 lan0 4136
192.168.101.0 192.168.101.8 U 2 lan0 1500
127.0.0.0 127.0.0.1 U 0 lo0 0
default 192.168.101.1 UG 0 lan0 0

Also update resolv.conf and nsswitch file accordingly.

Regards,

Re: Network Unreachable

Timothy P. Jackson — Fri, 01 Apr 2005 01:49:02 GMT

here is my netstat -rn

Routing tables
Destination Gateway Flags Refs Interface Pmtu
127.0.0.1 127.0.0.1 UH 0 lo0 4136
192.168.101.8 192.168.101.8 UH 0 lan0 4136
192.168.101.0 192.168.101.8 U 2 lan0 1500
127.0.0.0 127.0.0.1 U 0 lo0 0
default 192.168.101.1 UG 0 lan0 0

It looks good as far as I can see.

my resolv.conf is correct and nsswitch.conf looks good.

Re: Network Unreachable

RolandH — Fri, 01 Apr 2005 01:52:00 GMT

You must switch off the dead gateway detetction on your hp-unix box

# ndd -set /dev/ip ip_ire_gw_probe 0

Roland

Re: Network Unreachable

Timothy P. Jackson — Fri, 01 Apr 2005 02:09:43 GMT

I tried the command

ndd -set /dev/ip ip_ire_gw_probe 0

and it had no affect on the problem. do I need to stop and start the net again?

Re: Network Unreachable

RolandH — Fri, 01 Apr 2005 02:19:22 GMT

YES. See also the ndd manpage how you can change this to be permanent after reboot.

Roland

Re: Network Unreachable

Ron Kinner — Fri, 01 Apr 2005 09:51:49 GMT

RolandH is correct about the cause of your problem. If restarting the net doesn't bring it back to life try removing the route and then adding it back. The mechanism to restore the dead gateway stops working after you turn it off in NDD. It doesn't automatically restore all dead routes.

To make your change permanent you need to edit /etc/rc.config.d/nddconf to add:

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

Use the next available integer in the brackets if you already have entries there.

To give you a little more insight there is a three minute timeout period after it first knows about the gateway. Normally this timeout period begins when it starts the network or you add the route but I think it will also turn on the gateway for 3 minutes when it gets a gratuitous arp from the router (which the router sends out when you reboot it).

Ron

Re: Network Unreachable

Timothy P. Jackson — Fri, 01 Apr 2005 11:03:25 GMT

I currently do not have a nddconf file. Is this a file that I can just add and it will be read by an existing script?

So I rebooted my ISA server / firewall last night and everything started working again, very wierd. It is still up and working, so I am taking great care to document what I do so that if it stops again I will know what I did.

Does it ever hurt to set the nddconf?

Re: Network Unreachable

Ron Kinner — Fri, 01 Apr 2005 13:27:32 GMT

If you were able to run the ndd command then the netconf file should have been there. You can create one if you don't have it. Just put the three lines in from my previous post and then save the file as /etc/rc.config.d/nddconf.

I'm not sure of the permissions. Probably it is enough for everyone to be able to read it so the default should work OK.

Ron

Re: Network Unreachable

Timothy P. Jackson — Sat, 02 Apr 2005 01:19:21 GMT

Thanks for everyones help on this!!

I added the nddconf file and rebooted both the HP-UX server and the MS ISA server. Every thing has been up and working since then.