Have you rebooted your Linode at least once since enabling the private address in the Linode Manager? If not, you won't be able to use the address until you do, regardless of the local configuration of the Linode.

If you have, could you be filtering (intentionally or unintentionally - such as by broad restrictive default rules) the private address space on either this Linode or the other Linodes you are trying to test against? If you are using iptables on either Linode, you may wish to simply disable them entirely for the test as a check.

– David

Thanks for replying David.

I did reboot this linode night before last. I just verified the firewall by stopping it on both linodes, and no joy. I have not rebooted the linode I am pinging from. I would guess that is not necessary.

Just to check on the reboot - the key is that any Linode using a private address gets restarted after the address is first assigned in the Linode Manager (or else the private address won't work). So this holds for both the target Linode as well as the "pinging from" Linode. And for the target Linode, "night before last" is only good if you assigned the private address in the manager prior to that reboot.

The ifconfig output (the configuration is for a distribution I don't use, but looks reasonable) appears ok for the private address setup. What does the same configuration on the other Linode look like?

Any chance there's a typo in the address on either Linode that doesn't match the value shown in the Linode Manager?

– David

Thanks again David.

I had no idea that the "ping from" system would need to be rebooted. I have just been working with this from our test system, so I have not messed with the others. Can I assume from this that whenever a private IP is added to a linode, all other linodes will need to be rebooted to recognize it? Thus, when I add a private IP to another, say dev, the test system will need to be rebooted again to see dev's private IP?

Gary

@grickert:

Thanks again David.

(…) Can I assume from this that whenever a private IP is added to a linode, all other linodes will need to be rebooted to recognize it? (…)
No. I probably wasn't clear. Each individual Linode must be rebooted after it has a private address first added in the Linode Manager for that address to be valid within the guest OS running on the Linode. But after that first reboot following assignment of a private address, it'll continue working to the private address space in general.

It just wasn't clear to me from posts so far when the test Linode got its own private address, and if it, too, had been rebooted afterwards. Since the issue could have been at the test side in addition to the target, that's why I mentioned that.

– David

Thanks David,

Let me be a little more verbose, and hopefully figure this out.

I went into the linode manager for TEST and assigned the Private IP. I had read the Static Networking Guide and as indicated restarted networking, and successfully pinged both IP's from a TEST ssh session.

I then went to a DEV shell, and attempted to ping them with no success to the PrivateIP. I then started searching around and found somewhere that a reboot was required, so I rebooted TEST, and am still not able to ping the PrivateIP from DEV.

From your reply, I now believe that DEV will need to be booted. Now before I boot it, I am going to assign and configure a private IP for DEV. Now after I boot DEV, should I be able to ping DEV from TEST without rebooting TEST again?

Any insight into what is actually happening with this process to help me understand/absorb this would be appreciated.

Thanks again for all the help.

Gary

@grickert:

Thanks David,

Let me be a little more verbose, and hopefully figure this out.

I went into the linode manager for TEST and assigned the Private IP. I had read the Static Networking Guide and as indicated restarted networking, and successfully pinged both IP's from a TEST ssh session.

I then went to a DEV shell, and attempted to ping them with no success to the PrivateIP. I then started searching around and found somewhere that a reboot was required, so I rebooted TEST,
At this point you should have been good on TEST, at least as far as its access to the private network. Prior to that reboot the private address would not have been reachable from any other Linode. It worked locally since the guest OS recognized the internal address as itself, and it never had to leave the local Linode through the host.

> and am still not able to ping the PrivateIP from DEV.

From your reply, I now believe that DEV will need to be booted. Now before I boot it, I am going to assign and configure a private IP for DEV.
If I'm reading this right, does that mean that through this point you had not yet assigned a private IP on DEV (both in the manager and on the guest itself) and then rebooted? If not, then DEV would certainly not be able to reach TEST over the private network since it simply didn't have an interface on that network. But yes, I would expect that if you assign a private address to DEV in the manager, update it's local guest configuration to match and then reboot, that it should be able to now reach TEST.

> Now after I boot DEV, should I be able to ping DEV from TEST without rebooting TEST again?
Yes. The reboot would be to ensure DEV had a working private interface, which TEST already has from its own earlier reboot.

> Any insight into what is actually happening with this process to help me understand/absorb this would be appreciated.

Thanks again for all the help.

Gary
Not sure how best to clarify further, but it's a question of the private address being working both internally on your guest and then externally on the host. So for each Linode, the process is essentially:
* Add a private address in the manager. This updates your configuration but makes no changes to live systems.

• Configure your Linode. This lets your guest OS recognize the private network traffic when it arrives or is generated. (You can also do this step after the reboot, but then will need to refresh the configuration locally such as restarting networking to avoid another reboot).

• Reboot your Linode. When it restarts, the host obeys the manager configuration and understands to map traffic for the assigned private address to your Linode.
  It's not a perfect analogy, but you could think of the host as a router on the private network. Without it knowing about your private address (which it picks up during the first reboot after assigning the private address in the manager) you can do stuff locally on your Linode but can't reach the outside world (where outside in this case is just the local data network).

– David