IP Logical Interface

[John Jimenez]

Hi guys,
I was hoping that you might have some isite on a problem that I encountered this weekend with two RP7420 servers, clustered with Oracle RAC, running 11.23.

Both of these servers have an "IP Logical Interface on the NIC card of LAN0. What is coincadance is that a 2 weeks ago our Application Vendor wanted Citrix access to these IP addresses. At that time I did not even know these IP addresses existed. At that time I went to /etc/rc.config.d/netconf and ther was no entry for this IP Logical Interface. But SAM did see it. I scrached my head wondering how it was working and what file would this entry be at.

Saturday morning no one was able to log into the application. Our network Admin happened be said that "Openview" showed that one of these Logical IP addresses went down at 9:10 AM. I went into SAM of both systems and they were gone. I have never created one of these before, so I used SAM to re-create the IP Logical Interface. Now I see it in the /etc/rc.config.d/netconf file.

I am trying to trouble shoot what happened on Saturday. But the problem is that I do not even understand how this IP logical Interface was created on the installation, by the application vendor, 2 years ago.

Are there multiple ways of creating an "IP Logical Interface"?

I went ahead and grabbed the /etc/rc.config.d/netconf files and put them in the home directory. The time stamps on both of the files are Feb. 2006 and there are definatly no entrys for these Logical Interfaces in those files like they are on the ones I recreated Saturday.

[Ivan Krastev]

Grep for 'ifconfig' in /sbin/init.d/ directory.

You may have any script, which enable/disable this interfaces.

regards,
ivan

[David Bellamy]

Yes there are multiple ways to create the logical ip interface. One way is ifconfig lan0:1 inet 192.168.1.1 will assign that address on top of the regular address for that interface.

[John Jimenez]

Ivan,
3 files have ifconifg, but the time stamp is 2004, which means that these files have never been modified.

maxux1:[/sbin/init.d]
# grep ifconfig *
net:# The ifconfig(1m) command assigns an IP address to a LAN interface and
net:# See ifconfig(1m)
net:# Do ifconfig commands for each interface
net: emsg=$(ifconfig $MODLIST $NAME nofastpath $IP $MASK $BCAST $STATE 2>&1)
net: emsg=$(ifconfig $MODLIST $NAME $IP $MASK $BCAST $STATE 2>&1)
net-ipv6:# The ifconfig(1m) command assigns an IPv6 address to a LAN interface
net-ipv6:# See ifconfig(1m)
net-ipv6:# Do ifconfig commands for each interface
net-ipv6: emsg=$(ifconfig $MODLIST $NAME inet6 $LINKLOCAL_ADDRESS $STATE $FLAG)
net-ipv6: emsg=$(ifconfig $INTERFACE \
net-ipv6: emsg=$(ifconfig $INTERFACE \
net-ipv6: emsg=$(ifconfig $NAME inet6 tunnel $TYPE $LADDR $RADDR \
net-ipv6: emsg=$(ifconfig $NAME inet6 tunnel $TYPE $LADDR $RADDR \
net.init:emsg=$(ifconfig lo0 $IP up 2>&1)
net.init:emsg=$(ifconfig lo0 inet6 $IP up 2>&1)

[A. Clay Stephenson]

Bear in mind that these logical IP addresses could have been created "on the fly" either as a result of a specific ifconfig being issued from an interactive shell or within an application. You are looking in the standard locations for these entries but since these files have not been modified, it could well be that your application creates these IP's.

[John Jimenez]

Clay,
thank you. I am trying to contact my application Vendor to see if they have a standard method that creates this. The Consultant who installed this, no longer works for the company any longer, so I have a feeling that they may not have or know of a standard way. I will update you and let you know what they say.

[John Jimenez]

Is it possible that this could have been soley created in DNS. Saturday morning we had DNS issues. Is it possible that there was an entry in DNS and it got deleted there?

[Patrick Wallek]

No, not really. DNS is merely a lookup facility that allows you to translate names to IP addresses and vice-versa.

In order for an IP address to actually respond on a system it has to be configured somehow (ifconfig, /etc/rc.config.d/netconf and reboot, or via SAM).

[Torsten.]

The IP address could be related to serviceguard, if installed ...

[John Jimenez]

Torsten,
We are not running Service Guard, only RAC.

[John Jimenez]

David,

I just re-read your reply again. If you set it up with the ipconfig command, are you saying this way will not update the /etc/rc.config.d/netconf file?

[Patrick Wallek]

That is correct.

If you were to do something like:

# ifconfig lan1:1 1.2.3.4 255.255.255.0

Then you would have IP address 1.2.3.4 assigned to lan1:1. However, if you were to reboot at this point, then 1.2.3.4 would go away because /etc/rc.config.d/netconf has NOT been updated.

The ifconfig command configured the interface, but does NOTHING else.

[John Jimenez]

Thanks Patrick. The systems were rebooted many times the last couple of years, and the IP's always remained.

There must be or must have been a script some where.

[Bill Hassell]

Two other (very non-standard hacks) ways to set things on reboot:

grep ifconfig /sbin/rc?.d/*

Normally, /sbin/rc directories are used to link init.d scripts but non-HP-UX admins may dump some custom startup script(s) in rc2.d and rc3.d.

The other (poor) way to do this is in inittab, usually with a script.

To see all the active LANs including logical or secondary IPs, use:

netstat -in

The ifconfig command sets the primary lan address with an index of :0, so lan0 and lan0:0 are the same for the primary address. Extra addresses on the same lan start with index :1 and so on.

[rick jones]

It is possible that the scripts, particularly if they were third-party, are outside of the standard init tree, so broadening the search to include additional tree's - perhaps even everything under / :) - might be a worthwhile endeavour.