[Solved] Using "Admin > Backup" and pitfalls

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krby
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PostPosted: Tue Apr 07, 2020 17:19    Post subject: [Solved] Using "Admin > Backup" and pitfalls Reply with quote
MODS: This may not be Atheros specific, please let me know or move it to the appropriate place

Is it possible to make a complete backup of the config of R7800 and get it on another R7800? Will this catch all settings including startup scripts and such?

I've got one flashed with DD-WRT r42819 and another still stock from the factory. When I'm done setting up the first one, I'd like to mirror it's config to the second one, make a few tweaks manually (like IP address) then place them both in their final locations.

What's the best way to do this? I can see two general approaches:
1) Flash the 2nd one with .img for to get DD-WRT running first, then backup config from 1st and restore it on the 2nd. Will this get everrthing? I care most about VAPs, VLANs, and Bridge configs.

2) [i]Not sure this is possible[/], Kind of like imaging a hard drive with dd: Take a complete image of the 1st one, somehow flashing it on to 2nd one. Upgrading to DD-WRT and getting the settings all at once.


Last edited by krby on Tue Apr 07, 2020 18:12; edited 2 times in total
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msoengineer
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PostPosted: Tue Apr 07, 2020 17:55    Post subject: Reply with quote
In Theory, you should be able to if using the exact same build. But, I have seen posts on here where it can go bad on other model routers.

That said, I have sent BS my backup files in the past and he had no issues explicitly for R7800 and R9000, FWIW.

If you "brick it" with a backup file, TFTP is always possible on the R7800.

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krby
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PostPosted: Tue Apr 07, 2020 18:07    Post subject: Reply with quote
Ok, so recommended procedure is to:
1) Take backup on R7800-1 running r42819
2) Use img file for r42819 to do initial flash of R7800-2 from Netgear stock to DD-WRT
3) Restore backup from step 1 onto R7800-2
4) Reboot R7800-2, check settings, adjust the few things that I want to be different

Right?

Or...should I be using a different img file for the initial flash of R7800-2 and doing a .bin upgrade to r42819?


Last edited by krby on Tue Apr 07, 2020 18:13; edited 1 time in total
kernel-panic69
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PostPosted: Tue Apr 07, 2020 18:11    Post subject: Reply with quote
You should be able to flash the .img file and restore settings, in theory. I personally used the installation guide by egc using the <Kong> .img and then upgraded from there.
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bvideo
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PostPosted: Tue Apr 07, 2020 23:35    Post subject: Reply with quote
The backup file contains your scripts and all. It also contains *some* mac addresses that were probably originally derived from the router's native config. (For wifi 2.4 & 5 GHz and switch/LAN/WAN).

The question would be does restore from the 1st router's backup override the 2nd router's native mac addresses? I see that some GUI pages (e.g. Setup->Networking) seem to treat MACs as variables. It might be a good idea to capture the 2nd router's MAC addresses from a default config before restoring the new config over it, just in case. I assume you want both routers active where other equipment could see both at the same time, so you don't want them using the same MACs.

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msoengineer
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PostPosted: Wed Apr 08, 2020 4:53    Post subject: Reply with quote
So I just found this neat little tool someone made on this post to quickly look at the nvram backup that is made when you backup your settings...

TL:DR- mac addresses are saved...so backing up on one router and loading that backup onto another router will possibly overwrite mac addresses and cause goofiness/gremlins/brick.

I will ask BS for further clarification unless another guru chimes in while we wait...

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kernel-panic69
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PostPosted: Wed Apr 08, 2020 5:21    Post subject: Reply with quote
There is also this one for the really masochistic: https://github.com/0ki/ddwrt-nvram-tool
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msoengineer
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PostPosted: Wed Apr 08, 2020 12:47    Post subject: Reply with quote
My email to BS and his reply:

I saw the nvram editor tool and see that when you make a backup the mac addresses are saved. Given that, if someone has two identical routers, same build, and they save the nvram backup and load it onto the second router to save time on config, will that brick/spawn gremlins, or is that ok and the router will still load it's hard baked key details like MAC addresses?

Brainslayer wrote:

depending on the router model variables which may brick devices will be ignored. this includes also mac addresses. so its all backed up, but not all will be restored
see the big filterlist here in this sourcecode https://svn.dd-wrt.com/browser/src/router/nvram/backup.c and the function "nvram_critical_internal"



I assume this is not advisable, but wanted to check.


Brainslayer wrote:
you can do that without any issue. its just not advices to backup and restore between different device models. since they may have different interface names (eth0 vs vlan1 etc.)
and wan port assignments. so the resulting network configuration might be bad. but if the interface usage is identical you can also use the same backup on different models

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FORUM RULES

TIPS/TRICKS: Best QCA Wifi Settings | Latency tricks | QoS Port priority | NEVER USE MU-MIMO |
Why to NOT use MU-MIMO | Max Wifi Pwr by Country | Linux Wifi Pwr | AC MCS & AX MCS | QCA 5Ghz chnls to use | WIFI Freq WIKI | TFTP R7800 | Don't buy AX | IPERF3 How-To

[R9000]49197 nightly (Main Router)
[EA8500]43192 & 45493 (2xOffsite)
[R7800] resting
[WDR3600]BS 44715 (Offsite)
[A7v5]BS 43038 (Offsite+spare napping)
msoengineer
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PostPosted: Wed Apr 08, 2020 12:54    Post subject: Reply with quote
I have modified the name of this topic slightly to make it more clear and I'm going to make it a sticky.
_________________
FORUM RULES

TIPS/TRICKS: Best QCA Wifi Settings | Latency tricks | QoS Port priority | NEVER USE MU-MIMO |
Why to NOT use MU-MIMO | Max Wifi Pwr by Country | Linux Wifi Pwr | AC MCS & AX MCS | QCA 5Ghz chnls to use | WIFI Freq WIKI | TFTP R7800 | Don't buy AX | IPERF3 How-To

[R9000]49197 nightly (Main Router)
[EA8500]43192 & 45493 (2xOffsite)
[R7800] resting
[WDR3600]BS 44715 (Offsite)
[A7v5]BS 43038 (Offsite+spare napping)
krby
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Joined: 05 Apr 2020
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PostPosted: Wed Apr 08, 2020 13:51    Post subject: Reply with quote
Thanks for checking! So from BS' reply:
Quote:
you can do that without any issue...so the resulting network configuration might be bad. but if the interface usage is identical you can also use the same backup on different models


I interpret that to mean across the exact same model and revision on the same build of dd-wrt, restoring a config should not brick, but it might lead to an invalid network config out of the box depending what the exact router restores from the backup (MACs etc).

So, I'll take the advice of noting down MACs for the various interfaces, then restoring, and updating those if I need to.
kernel-panic69
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Location: Texas, USA

PostPosted: Wed Apr 08, 2020 13:59    Post subject: Reply with quote
Better safe than sorry. You can always reset the second router or use `nvram set` to fix the mac addresses followed by `nvram commit && reboot`. But, you better know what you're doing...
_________________
"Life is but a fleeting moment, a vapor that vanishes quickly; All is vanity"
Contribute To DD-WRT
Pogo - A minimal level of ability is expected and needed...
At some point, people just get plain tired of this place.
Because they are tired of bottom-feeders and the same old hat.

----------------------
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krby
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Joined: 05 Apr 2020
Posts: 21

PostPosted: Thu Apr 09, 2020 1:41    Post subject: Reply with quote
Quote:
So, I'll take the advice of noting down MACs for the various interfaces, then restoring, and updating those if I need to.


I just did a backup on unit 1, restored on unit 2, and it worked! So on the R7800, the MAC addresses from the original bin file don't appear to get restored.
msoengineer
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Posts: 1779
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PostPosted: Thu Apr 09, 2020 3:27    Post subject: Reply with quote
...And that is what BS said would happen.
_________________
FORUM RULES

TIPS/TRICKS: Best QCA Wifi Settings | Latency tricks | QoS Port priority | NEVER USE MU-MIMO |
Why to NOT use MU-MIMO | Max Wifi Pwr by Country | Linux Wifi Pwr | AC MCS & AX MCS | QCA 5Ghz chnls to use | WIFI Freq WIKI | TFTP R7800 | Don't buy AX | IPERF3 How-To

[R9000]49197 nightly (Main Router)
[EA8500]43192 & 45493 (2xOffsite)
[R7800] resting
[WDR3600]BS 44715 (Offsite)
[A7v5]BS 43038 (Offsite+spare napping)
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