Deleting ISP-issued settings from UBOOT config partition

Installing and Using OpenWrt
1

Hi there,

after reading this discussion and faced with a similar issue of low power output on the 2.4GHz band with an old DIR-821B1, I dumped the mtd1 partition containing the config data. This router was formerly branded to an ISP.

And lo and behold, even though OpenWRT is installed, the original ISP settings are still present in the config data, mainly the original SSID as well as the TR-069 settings. Now I really doubt the ISP would be interested in connecting to an old router from a non-customer, nevertheless, I'd like to get rid of those non-essential settings, just to be on the safe side.

I also found strings wlan0_txpower=19 and wlan1_txpower=19, and while I can't be sure of it, I suspect this setting prevents OpenWRT from using a higher power.

I could edit both and point the TR069 parameters to a non-working URL, and set the txpower to what's allowed, but how do I write back the modified file?

I thought about:

  1. Use LuCI to get a .bin dump from mtd1
  2. Open in Hex Fiend (or any hex editor)
  3. Edit settings
  4. Save in .bin format
  5. Upload modified file through SFTP
  6. Use dd to write modified file to mtd1 partition
  7. reboot router

Or a simpler version:

  1. Install jupp
  2. From the command line, open mtd1 partition
  3. Remove / edit relevant settings
  4. Save file
  5. Reboot router

Ideas?

2

Please post output of ubus call system board , if your device is supported by mainline OpenWRT be assured no provider configs are kept.
In particular uboot environment parameters are not used to set up hardware, nor any specialist uci-defaults lurk in squashfs.

3 
# ubus call system board
{
	"kernel": "5.10.176",
	"hostname": "DIR-825B1",
	"system": "Atheros AR7161 rev 2",
	"model": "D-Link DIR825B1",
	"board_name": "dlink,dir-825-b1",
	"rootfs_type": "squashfs",
	"release": {
		"distribution": "OpenWrt",
		"version": "22.03.5",
		"revision": "r20134-5f15225c1e",
		"target": "ath79/generic",
		"description": "OpenWrt 22.03.5 r20134-5f15225c1e"
	}
}
4

First check that you have chracteristic OpenWRT flash partitioning
https://openwrt.org/toh/d-link/dir-825#flash_layout

Probably back up config and acquire provider's sysupgrade file if possible. There might be some use for their connection parameters like lowered mtu and similar.

Now just sysupgrade?

https://firmware-selector.openwrt.org/?version=23.05.4&target=ath79%2Fgeneric&id=dlink_dir-825-b1

5

Hi Cubytus
I don't believe these settings affect OpenWRT at lest as the radio's
I just had a look at as some of my old dumps of my 2 DIR-825-B1's
they had old setting in them as well
there maybe a checksum you would have to correct if you manually edited the data
the better thing to do would be reverting to the old DLink 825-B1 firmware
do a factory reset in that firmware, it will know what to keep eg SSID's on label etc
then return back to openwrt

the partition that affects the radio is the caldata
MTD6 in my old saves but MTD5 on that chat on the support page 64K in size
it is possible if you used the old V19 Big firmware and you didn't nicely sysupgrade
you may have lots this data as it moved that data to a new location
but if you had to recover back to a different firmware it may not have moved it back
tho it did ask in the usage instructions to backup this partition some didn't or lost it

I do remember for windows 10
I had to install netscape navigator to use the old recovery page
as modern browsers didn't work

as for the 2.4G radio is it a Maximum transmit power not the same on both units
under th same firmware in he same region on the same channel ?

6

I think asking the original ISP to provide a non-customer with their sysupgrade file for a 12-year old router found on the curb is stretching it. They aren't getting paid to help some random dude with a strange obsession for sustainability.

As for the flash layout, yes, I got the same as shown in the wiki.

I'm not fully sure how I installed OpenWRT first as it was quite a while ago, probably did a factory reset first on the ISP firmware, then modified the D-Link original firmware, then installed it before OpenWRT. In any case, it didn't erase the ISP-issued values that have nothing to do here anymore, especially not ones related to remote management.

The mtd3 caldata partition is unreadable

As for the txpower, indeed it's the same for both bands, even though some channels should have higher available power

@brada4 My mistake, it isn't in the UBOOT partition, but in config (mtd2)

7

Compare /proc/mtd with toh page, if it is same sysupgrade to any newer openwrt

8

In fact it's the same. However, so far I refrained from upgrading because this router being my main AP, I had to modify the default configuration to create an extroot on a USB flash drive. As this board has very low amount of Flash, I couldn't follow the standard instructions from the wiki as required packages wouldn't all fit at the same time.

For some reason, on every other router with extroot where I tried to update, even saving all settings, it failed to acknowledge the existing flash drive, and also failed when I modified /rwm/upper/etc/config/fstab. (A known bug, apparently). I have to isolate it from the LAN first, then connect with an Ethernet cable, then apply all modifications. A pain.

I can avoid the issue by temporarily using another router with same SSID and modify phy0-ap0 to have the same MAC address, even though it's akin to avoiding the issue rather than solving it :wink:

As for the lower MTU: I vaguely remember a "1492" value being used in some cases in some ISPs ADSL or cable modems, but no idea of its exact purpose. This being originally an ISP-issued router, there may be performance reasons behind such a setting.

9

The original firmware size is limited, but extra is available to OpenWrt
so if you want to compile it in, you first have to upload a firmware which fits inside the size
of the original factory limitation
but you can then sysupgrade your bigger image from that
this will use the extra concatenated image space

oh here is the dlink OEM firmware i was talking about
http://files.dlink.com.au/products/DIR-825/REV_B/Firmware/Firmware_v2.06/DIR825B1_FW206WWB05.zip

10

It is already flashed with something openwrt-likei