topic Router/GW/ Conflict in Operating System - HP-UX

Router/GW/ Conflict

Julian Snype — Tue, 27 Apr 2004 21:45:18 GMT

j5000ws /hp-ux 11i
cable modem/linksys router/firewall

I wanted to make sure that I could ping all IP's on my network.
#1 - I cannot ping my gw or my broadcast subnet, however I can ping the IP address that I assigned, other worksta on my network, www.google.com and I can ping the IP that assigned to the unix box from another worksta.
In my DHCP client table I can see the assigned IP's for all other worksta on the network, except the unix box.
I checked my routing tables (netstat -rn/-r ) and the default is setup correctly
I deleted the route and then added it back.

The problem could be that I'm assigning a unique IP and not letting my DHCP server assign it.

1st I would like to know what is the correct way for the unix machine to recognize the dynamic IP address from my DHCP server without hardcoding a unique IP. There are certain files that must stay in sync for me to boot.
When I let the DHCP server assign the IP there is a possibility that the IP in netconf could be different from the unique IP address in /etc/hosts, this file is not updated after a reboot. If the following files are out of sync I cannot boot my system.
So I did the following:

/etc/hosts
assign a unique IP

/etc/rc.config/netconf
assign unique IP
disable -DHCP_ENABLE=0

etc/nsswitch.conf
host: files dsn

This may also be a reason why I cannot ping my gw

Thanks
Julian

Re: Router/GW/ Conflict

Steven E. Protter — Tue, 27 Apr 2004 22:02:19 GMT

Something to check:

subnet compatiability. For the ping to work, you may need to make sure the hp box is on the same network and subnet as the router.

These problems are commonly caused by inconsistencies in network, broadcast address parameters on one machine.

For hpux, check /etc/rc.config.d/netconf

also check ifconfig for all the lan cards.

Do note that hpux does not support two nic cards on the same network. period.

Also, because of recent ping attack viruses, your router may be configured to ignore pings. That should definitely be done to preven outsiders from discovering and attempting to sniff your network.

Does nslookup work?

If nslookup and the internet work, you don't need ping for an 11i box to work.

SEP

Re: Router/GW/ Conflict

Ron Kinner — Wed, 28 Apr 2004 14:43:42 GMT

If the Linksys is providing the DHCP service then you can simply tell it to use a higher DCHP IP starting address to make room for static addresses at the low end of the range. Normally the router grabs 192.168.1.1 and DHCP service starts at 192.168.1.2 (Starting IP address) and runs up through Starting IP Address + Number of DHCP Users. If you want to reserve some addresses for static address use, simply change the Starting IP address to 192.168.1.25 and then you can use the addresses from 192.168.1.2-192.168.1.24 for static addresses. You can also reduce the Number of DHCP users and then it will leave space at the high end.

ftp://ftp.linksys.com/pdf/befsr11_befsr41ug.pdf page 57 (PDF page 32of66)

Just make sure you use a mask of 255.255.255.0 and a default gateway of 192.168.1.1.

If the default gateway is the linksys and it will not respond to pings you may run into problems with dead gateway detection. The HP likes to consider a gateway dead if it doesn't respond to pings. You can check with:

ndd -get /dev/ip ip_ire_gw_probe

if it comes back with 0 then it is turned off and it won't bother you. If it is on you can fix it for good with an edit to /etc/rc.config.d/nddconf

TRANSPORT_NAME:=icmp
NDD_NAME:=ip_ire_gw_probe
NDD_VALUE:=0

which will take effect after a reboot. You can get around the reboot by

ndd -set /dev/ip ip_ire_gw_probe 0

then use route to delete and readd the default gateway.

The Linksys also has an option to turn off pings. It says it keeps it from responding to pings from the outside but it may also kill off the inside pings.
Think it is called Block Anonymous Internet Requests and is under Block WAN Requests under Security.

Ron

Re: Router/GW/ Conflict

Julian Snype — Wed, 28 Apr 2004 17:31:42 GMT

Ron,

Thanks for the info.
Your synopsis of configuring the Linksys DHCP service was somewhat similar as to how I configured mine. Thanks this confirmed that my configuration was ok.the way it is setup.
I previously checked NDD and edited nddconf and added those NDD optioins.
The gw was ok.

There was one bit of info that you mentioned that was a very big help. I enable my WAN and pinged my gw and broadcast subnet successfully. enable it after a successfully ping.
My Gw/router is configured correctly. This put my mind to rest. Thanks a lot for the documentation this was also a big help.

Thanks
Julian