Old Core wallet to Knots

Bitcoin
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Hi, I found this forum trying to find people that use Knots. I hope someone knows how to do this.

If there is an old 2013 Bitcoin Core wallet.dat which was last used a in 2015 version of Core and you want to run Knots, given that the wallet is an old format, what should you do to not screw up in the process?

It appears there are 2 options, “Migrate wallet” and “Restore wallet”. Not sure what they do and in what order that must be done. Of course backups do exist, but I want to know what is going on.

The end goal is to have a setup like this:

  1. Laptop 1: It runs Bitcoin Knots full node, with the full blockchain synced, used to broadcast transactions and be able to monitor the wallet in watch-only mode.
  2. Laptop 2: It runs Bitcoin Knots as a wallet, to craft transactions, never connecting to the internet, and then send this transaction into the Laptop 1 node, and broadcast it.

I think back then you had to use the console with some convoluted raw transaction commands that you would risk you type the wrong comma at the wrong spot or copy paste the wrong address and screw something up. I think right now there is the PSBT thing that is integrated within the GUI. Ideally, I could use Coin Control, select what addresses I want to use to send the coins, and then generate a PSBT file that contains this information, and then you load this file into the node on online laptop to broadcast the transaction. I have never done this, so I will test first with testnet coins. But hopefully someone knows how to do it properly here.

But for now, let’s first solve how to port the old wallet file into the new wallet format without screwing things up. Then we can later worry about how to do the 2 laptop setup to transact. Meanwhile I will continue to sync the node which is taking like 4 days, so im posting this here so meanwhile I can learn how to do the next steps.

I am using Debian 13 btw, on both laptops. I have to install it on the cold storage laptop, where I will load the wallet, this is the offline wallet. Then I will need to learn how to generate a watch-only wallet for the online laptop. Then I need to learn the PSBT thing to make the transactions. It’s a lot of work and I don’t want to create a separate thread for each thing, so maybe we can solve this here? I understand things better if they are step by step, ideally in video but I didn’t found them, so im asking here. The manuals are not enough, I would like to talk to someone that has actually done it and encountered and solved any problems in this proces.

Please let me know. Thanks

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Disclaimer: I have not done this process exactly, so there will likely be inconsistencies to work through. I have done a more-or-less analgous process with Electrum and an old paper wallet so the broad strokes should be similar.

Backups & hygiene (most important)

  1. Make at least 2 copies of the original wallet.dat on separate media (e.g., two USB thumb drives).
  2. On Debian, run sha256sum wallet.dat and write the hash on paper; verify each copy matches.
  3. Do not reuse the original file; always work on a copy. Never open the same wallet in two places at once, where if something were to go wrong you would lose both copies.

Prepare the two laptops

Laptop 2 (offline signer):

  • Physically remove WiFi and Bluetooth radios if possible. Physically disconnect any network cable. Once powered up into Debian, run: rfkill block all.
  • Copy over Knots via USB after verifying the signatures.
  • Create a private wallet directory (permissions 700), e.g. ~/knots_wallets/legacy/, and put a copy of wallet.dat inside as wallet.dat.

Laptop 1 (online full node):

  • Run Knots as a full, non-pruned node (already done – just finish the IBD).
  • You’ll import a watch-only wallet here later.

Safest way to load and migrate the old wallet (offline only)

Knots should be able to open old Berkeley DB wallets as “legacy” wallets. The modern standard is a descriptor wallet. Migrating is one-way, which should be fine here since we are ensuring that we have backups.

On Laptop 2 (offline):

  1. Start Knots with your legacy wallet (GUI: “Open wallet” and point at the folder, or CLI with -walletdir pointing to ~/knots_wallets).
  2. Take another fresh backup from Knots (“Backup wallet”) so you have a post-open snapshot (just being paranoid here).
  3. Upgrade to descriptor (this might be labeled as “Migrate wallet” in the GUI; via RPC it’s upgradewallet). This creates internal descriptors for your keys/addresses. Note that I have not done this myself, so I am relying on various search results (there is some discrepency on the label – maybe due to different Knots/Core versions). Let me know if you can’t find anything that seems relevant here, and I’ll do some more digging.
  4. After upgrade, export public descriptors (GUI export if present, or RPC):
  • listdescriptors false > exports public (no private) descriptors, including active and internal (change) ones, with useful timestamps.

Save those descriptors to a text file on a clean USB (this file is safe to move – no secrets if you used false for listdescriptors).

Build the online watch-only wallet

On Laptop 1 (online):

  1. Create a new empty wallet (GUI: “Create wallet” > disable private keys / “watch-only”).
  2. Import the public descriptors you exported from offline:
  • GUI import (if present), or RPC importdescriptors with the JSON from your file.
  • Make sure the active, internal, range (for HD paths), and timestamp fields are preserved so Knots rescans correctly.
  1. Let it rescan the chain (can take a while). When done, balances and UTXOs should show as watch-only.

Sanity check:

  • On the offline wallet, generate a receive address and write it down.
  • On the online watch-only wallet, derive/show a receive address. It should match. (Matching here proves the descriptors line up.)

PSBT flow

Create (online):

  • In the online watch-only wallet, enable Coin Control. Pick the UTXOs, set outputs, and choose “Create PSBT” (GUI) or walletcreatefundedpsbt (RPC). Save the .psbt to USB.

Sign (offline):

  • On the offline wallet, open/sign the PSBT (GUI: “Load PSBT” > “Sign”; RPC: walletprocesspsbt). Save the partially or fully signed PSBT back to USB.

Broadcast (online):

  • On the online node, Finalize & Broadcast (GUI) or finalizepsbt then sendrawtransaction with the hex.
  • Verify the txid and watch it confirm.

Extra safety tips

  • Never plug the offline box into the internet, until you have drained the walllet and moved everything to a new home, and there have been many confirmations.
  • Label and keep your USBs separated: “PUBLIC (descriptors/PSBTs)” vs “PRIVATE (backups)”.
1 Like
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Hi, thanks for the very nice tutorial, I think I will be able to follow, but before trying any transactions, I will first try with a testnet wallet. I will need to see how to get testnet coins nowadays.

But for now, the node continues to sync. For some reason, at about 1 year and 25 weeks remaining or so, the download activity becomes very sparse, with gaps between activity. Right now I saw an huge 10 minute gap of no activity, then it downloaded a bit, then again is pausing. I was like 22 hours away from completing the sync, but right now it may take like 4 days… I don’t know why that happens.

I also had some checksum problems with some block files a couple times, that seems to be resolved by using -par=1. I think the CPU was overheating or who knows. Im using dbcache=2048 which I think is reasonable for 8GB ram. It is an external SSD with FDE enabled, plugged on a 3.0 USB port. The SSD drive is of a good quality brand and a relatively new model. The laptop is however 10+ years old, running an i5. Nonetheless, I don’t understand why at around 73% it’s when it started becoming really slow taking big breaks between activity. Hopefully this is not the result of non-monetary usages of the blockchain where the computer has to spend more time dealing with more complex signatures when you start downloading certain blocks or something. In any case, I will leave this running and hopefully it finishes this week. I hope this 2TB drive lasts before the blockchain fills it up because doing this from scratch is increasingly more time consuming when I have done it as the blockchain increases in size and complexity. I don’t trust using pruned more or assumevalid=1 so I do it the oldschool way only, meaning that I need to host the entire blockchain and fully check every block. Anyway thanks again for the tutorial, I will try whenever it’s done.

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It is exactly this. With 8GB RAM it will need to do a lot of file swapping (which is relatively slow even over USB 3.0). 8GB RAM is fine for normal everyday use, but the IBD is brutal. If you have any option to add another 8GB RAM, the difference would be substantial (otherwise it is just a waiting game).

1 Like
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Wow, so this showcases the importance of making Knots the #1 node and stopping the spam transactions. Most people that think non-monetary transactions are ok probably have never synced a full node in their lives, specially if you do it properly without any shortcuts like assumevalid or whatever. I think everyone should host a copy of the entire blockchain and anything that makes this more difficult is to be avoided. I think the full node software should give a warning about using assumevalid even, since if we keep promoting this pruning thing then at some point copies of the entire blockchain will be a relic and the whole point of Bitcoin is being able to trace everything back to the genesis block. So you don’t want to end up with a few full blockchains stuck on some old hdd’s because people stopped caring about maintaining them in the future.

Anyway, I will let it run and hopefully this ends before xmas.

1 Like
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Woke up with an speed of 0.02%, it will take like 8 weeks to finish, not normal at all. I don’t think that even with all the spam in the world it should take this long. Something going on with the computer probably. I may need to give up on the laptop and try to plug the SSD in the desktop and then hope it works as it would be plugging it into a different hardware, and also hope that it downloads faster. The desktop is much newer. Still would like to be able to run this in a laptop, but it will never finish as this rate.

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It should work on another computer as long as the OS is the same (or supports the same format). And when finished, you should be able to use it again back on the laptop. Does the desktop have more RAM?

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The node runs in an external SSD within an encrypted Debian installation so everything should stay the same except the drivers. I don’t know if Debian will simply find the drivers for the different hardware and run normally or it will give me a black screen of sorts due lacking drivers for the GPU or something. I guess there is only one way to find out. I remember trying from desktop install to the laptop and it seemed to work so I will try the other way around now and see what happens. Hopefully it works because the point of using an external SSD was to be able to have a portable node that you can connect on any computer on the go if needed. If you have different laptops in different spots or different desktops you could swap by simply carrying the drive.

But I did turn off the laptop for some hours and the speed improved, it was downloading at 2% per hour at some point with 10 hours remaining, but then it started going slow again and right now it’s at 0.3% with 2 days remaining. I will try to plug it on the desktop at night since im using it now. Yes the desktop is much more powerful with 32GB RAM and 16 cores. What dbcache and par values would you use? I’ve read that a third of the RAM is recommended, not sure about par. Im using par=2 right now on the laptop and it didn’t crash yet (it is a 4 core i5).

Looking at the size of UTXO chart in statoshi website this may explain why it gets worse around this time where it peaked at around 12GB. It’s down to 11.6GB now. Not sure if due peak of interest in Inscriptions stuff or the Knots anti spam nodes but hopefully it goes back to a more manageable size. But there was something abnormal going on when it was downloading at like 0.02%. I think the hardware was fried from hours of running with no rests or something, so at least right now it’s at 0.3%, sometimes higher but hopefully it doesn’t go back to mega slow progress. The temps did definitely go a bit lower and are now under 80ºC.

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Hi, I finally tried with the desktop. The desktop did in an hour what the laptop was going to take forever. So this shows there was not a problem with the portable SSD. Thankfully it did boot and apparently Debian is able to download drivers on the fly during boot or something, the thing is fastfetch shows the correct hardware specifications for my desktop, and now im back to the laptop with the node fully synced. This may be a solution for those struggling with older laptops, using a portable SSD for the node. However, I do not enjoy dealing with Bitcoin things in non-Corebooteable computers, but it was just impossible to finish the sync at this rate, and there are no private keys or even watch only wallets on the drive yet, and I doubt because of pluging it into a modern AMD desktop computer for some hours to sync it would be able to end up with some exploit installed on the SSD. The AMD desktop has 32 CPU threads and 32GB RAM so even with the spam it pushed through with ease.

The node is fully synced and thankfully once synched it seems it stays at a reasonnable temp on the laptop and it’s manageable, There is a small but constant stream of activity on the network graph. So everything seems to be ok now on the node laptop.

Now it’s time to install Debian on the airgap setup. The problem is I don’t have a secondary laptop available right now so im not sure what to do.

Should I wait to buy a secondary laptop, or would you install Debian in another portable disk and use the desktop and the laptop? I was planning to buy a secondary laptop and install Coreboot there to manage the private keys. Unfortunately the laptop im using for the node cannot have Coreboot installed I think. But for now it’s what I’ve got.

The thing is, I use the Guided installer with FDE for Debian since I don’t know how to manually set up the correct partitions, and depending on the hardware you install it, the guided partition setup will use a different swap size for instance, so ideally I want to have the hardware im going to finally use before I install it. I could I guess use the laptop to instal it, since it has similar settings to your average Corebooteable laptop, and meanwhile try to find a laptop. Im tempted to use the desktop but im just paranoid at using modern computers in general for these things. Anyway let me know what would you do from here. Thanks.

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To be a little pedantic, another thing that this shows is that 32GB RAM drastically reduces the amount of file IO necessary to complete the IBD (by orders of magnitude). In other words, there could technically still be an issue with the external drive itself related to file IO speed under load, which having the extra RAM would overshadow. Worth considering as a possiblilty in case it has future implications.

As far as the airgapped computer, I would suggest getting a separate dedicated system to run it on (you mentioned acquiring another laptop). Personally, in my case I use an old, low-spec, repurposed tiny PC (because they are robust, easy to work on, and I know how to physically remove the radios – a lot of laptops have the radios soldered into the motherboard and not possible to physically remove). But the drawback there is I also need a monitor, keyboard, and mouse, so they are less convenient than setting up an air-gapped laptop like you are doing.

Also, for the related process that I mentioned (moving funds from an old paper wallet to a more secure cold storage solution), I didn’t use Debian or Core/Knots, but rather in my case I used Tails OS and Electrum. So the context is different in your case so you have different constraints and risk analysis to work through.

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This laptop has compatibility with 16GB so I may upgrade. As far as using Electrum, yes I want to only use 2 Knot instances. Using different software increases complexity (not necessarily in the method, but just more variables).

I need to do this with testnet coins first. I forgot about how testnet works. I have to download it’s own testnet blockchain and get coins from some faucet? Anyone knows one?

And I also need to see how to do this through Tor.