Server Migration

[slowsquirrel]

We are migrating from one server running v20 to another one but the question I have the new IP addresses will change, so all my phone are provisioned

https://abc.ny.3cx.us:5001/provisioning/x5nf6ef2ow

as an example, how does the new provisioning get updated so it knows to talk to a new server. Everything will rename the same, just change ISP so we have a new IP address.

 

[Evolute IT]

If you keep the same 3CX FQDN, the IP will get automatically updated on the 3CX DNS. Phones use the FQDN so they'll connect automatically as well.

TTL for the DNS is 6h on Pro and 5min on Enterprise.

 

[slowsquirrel]

Thank you. That's why we are doing this over the weekend :>)

Wish us luck.

 

[caldwell]

If you can control the DNS that the phones "see", then you can put your own temporary glue/override record in your firewall/DNS server.

For instance, if your IP is changing from 1.2.3.4 to 4.3.2.1, you can put a TEMPORARY DNS override in your firewall or DNS server for any phones that USE it to say:

abc.ny.3cx.us. IN A 300 4.3.2.1

[Note: YMMV on setting the above. Each firewall is different. The free pfSense firewall has a simple GUI interface for this. Probably most firewalls worth their salt have a DNS override feature. Read the docs to find out how.]

Once the new server is up and running with the new IP and the phones provision, as noted above, after 6 hours, 3CX will have updated their DNS. Then you should remove the temporary DNS record.

Do you control 3CX's DNS? No.
Will this work? Yes.
Should you rely on this long term? No.

For those who don't know about this functionality, I've run an ISP for almost 30 years, and the reality is that anyone with control over a DNS server for DOWNSTREAM users can set their own DNS server to override any record for any domain. China can claim that www.microsoft.com is actually an IP that they control. That's why you should use DNS servers that you implicitly trust. That's also why this solution can work.

If this works for anyone, let me know or hit the Like.

 

[SteveITS]

Hadn’t really thought about that for migration purposes. Mostly because we’ve never moved one we host. But it’s basically this, just temporarily: https://www.3cx.com/docs/creating-fqdn-split-dns/

 

[slowsquirrel]

got it. thanks