Channel tools

Index

• Installation
• Overview
• Commands
  • dumpbackup
  • dumpchannels
  • filterbackup
  • forceclose
  • rescueclosed
  • showrootkey
  • summary
  • sweeptimelock

This tool provides helper functions that can be used to rescue funds locked in lnd channels in case lnd itself cannot run properly any more.

WARNING: This tool was specifically built for a certain rescue operation and might not be well-suited for your use case. Or not all edge cases for your needs are coded properly. Please look at the code to understand what it does before you use it for anything serious.

WARNING 2: This tool will query public block explorer APIs, your privacy might not be preserved. Use at your own risk.

Installation

To install this tool, make sure you have go 1.13.x (or later) and make installed and run the following command:

make install

Overview

Usage:
  chantools [OPTIONS] <command>

Application Options:
      --testnet          Set to true if testnet parameters should be used.
      --apiurl=          API URL to use (must be esplora compatible). (default: https://blockstream.info/api)
      --listchannels=    The channel input is in the format of lncli's listchannels format. Specify '-' to read from stdin.
      --pendingchannels= The channel input is in the format of lncli's pendingchannels format. Specify '-' to read from stdin.
      --fromsummary=     The channel input is in the format of this tool's channel summary. Specify '-' to read from stdin.
      --fromchanneldb=   The channel input is in the format of an lnd channel.db file.

Help Options:
  -h, --help             Show this help message

Available commands:
  derivekey      Derive a key with a specific derivation path from the BIP32 HD root key.
  dumpbackup     Dump the content of a channel.backup file.
  dumpchannels   Dump all channel information from lnd's channel database.
  filterbackup   Filter an lnd channel.backup file and remove certain channels.
  forceclose     Force-close the last state that is in the channel.db provided.
  rescueclosed   Try finding the private keys for funds that are in outputs of remotely force-closed channels.
  showrootkey    Extract and show the BIP32 HD root key from the 24 word lnd aezeed.
  summary        Compile a summary about the current state of channels.
  sweeptimelock  Sweep the force-closed state after the time lock has expired.

Commands

derivekey

Usage:
  chantools [OPTIONS] derivekey [derivekey-OPTIONS]

[derivekey command options]
          --rootkey=     BIP32 HD root key to derive the key from. Leave empty to prompt for lnd 24 word aezeed.
          --path=        The BIP32 derivation path to derive. Must start with "m/".
          --neuter       Do not output the private key, just the public key.

This command derives a single key with the given BIP32 derivation path from the root key and prints it to the console. Make sure to escape apostrophes in the derivation path.

Example command:

chantools derivekey --rootkey xprvxxxxxxxxxx --path m/1017\'/0\'/5\'/0/0 \
  --neuter

dumpbackup

Usage:
  chantools [OPTIONS] dumpbackup [dumpbackup-OPTIONS]

[dumpbackup command options]
          --rootkey=     BIP32 HD root key of the wallet that was used to create the backup. Leave empty to prompt for lnd 24 word aezeed.
          --multi_file=  The lnd channel.backup file to dump.

This command dumps all information that is inside a channel.backup file in a human readable format.

Example command:

chantools dumpbackup --rootkey xprvxxxxxxxxxx \
  --multi_file ~/.lnd/data/chain/bitcoin/mainnet/channel.backup

dumpchannels

Usage:
  chantools [OPTIONS] dumpchannels [dumpchannels-OPTIONS]

[dumpchannels command options]
          --channeldb=   The lnd channel.db file to dump the channels from.

This command dumps all open and pending channels from the given lnd channel.db file in a human readable format.

Example command:

chantools dumpchannels --channeldb ~/.lnd/data/graph/mainnet/channel.db

filterbackup

Usage:
  chantools [OPTIONS] filterbackup [filterbackup-OPTIONS]

[filterbackup command options]
          --rootkey=     BIP32 HD root key of the wallet that was used to create the backup. Leave empty to prompt for lnd 24 word aezeed.
          --multi_file=  The lnd channel.backup file to filter.
          --discard=     A comma separated list of channel funding outpoints (format <fundingTXID>:<index>) to remove from the backup file.

Filter an lnd channel.backup file by removing certain channels (identified by their funding transaction outpoints).

Example command:

chantools filterbackup --rootkey xprvxxxxxxxxxx \
  --multi_file ~/.lnd/data/chain/bitcoin/mainnet/channel.backup \
  --discard 2abcdef2b2bffaaa...db0abadd:1,4abcdef2b2bffaaa...db8abadd:0

forceclose

Usage:
  chantools [OPTIONS] forceclose [forceclose-OPTIONS]

[forceclose command options]
          --rootkey=     BIP32 HD root key to use. Leave empty to prompt for lnd 24 word aezeed.
          --channeldb=   The lnd channel.db file to use for force-closing channels.
          --publish      Should the force-closing TX be published to the chain API?

If you are certain that a node is offline for good (AFTER you've tried SCB!) and a channel is still open, you can use this method to force-close your latest state that you have in your channel.db.

!!! WARNING !!! DANGER !!! WARNING !!!

If you do this and the state that you publish is not the latest state, then the remote node could punish you by taking the whole channel amount if they come online before you can sweep the funds from the time locked (144 - 2000 blocks) transaction or they have a watch tower looking out for them.

This should absolutely be the last resort and you have been warned!

Example command:

chantools --fromsummary results/summary-xxxx-yyyy.json \
  forceclose \
  --channeldb ~/.lnd/data/graph/mainnet/channel.db \
  --rootkey xprvxxxxxxxxxx \
  --publish

rescueclosed

Usage:
  chantools [OPTIONS] rescueclosed [rescueclosed-OPTIONS]

[rescueclosed command options]
          --rootkey=     BIP32 HD root key to use. Leave empty to prompt for lnd 24 word aezeed.
          --channeldb=   The lnd channel.db file to use for rescuing force-closed channels.

If channels have already been force-closed by the remote peer, this command tries to find the private keys to sweep the funds from the output that belongs to our side. This can only be used if we have a channel DB that contains the latest commit point. Normally you would use SCB to get the funds from those channels. But this method can help if the other node doesn't know about the channels any more but we still have the channel.db from the moment they force-closed.

Example command:

chantools --fromsummary results/summary-xxxx-yyyy.json \
  rescueclosed \
  --channeldb ~/.lnd/data/graph/mainnet/channel.db \
  --rootkey xprvxxxxxxxxxx

showrootkey

This command converts the 24 word lnd aezeed phrase and password to the BIP32 HD root key that is used as the rootkey parameter in other commands of this tool.

Example command:

chantools showrootkey

summary

Usage:
  chantools [OPTIONS] summary

From a list of channels, find out what their state is by querying the funding transaction on a block explorer API.

Example command 1:

lncli listchannels | chantools --listchannels - summary

Example command 2:

chantools --fromchanneldb ~/.lnd/data/graph/mainnet/channel.db

sweeptimelock

Usage:
  chantools [OPTIONS] sweeptimelock [sweeptimelock-OPTIONS]

[sweeptimelock command options]
          --rootkey=     BIP32 HD root key to use. Leave empty to prompt for lnd 24 word aezeed.
          --publish      Should the sweep TX be published to the chain API?
          --sweepaddr=   The address the funds should be sweeped to
          --maxcsvlimit= Maximum CSV limit to use. (default 2000)

Use this command to sweep the funds from channels that you force-closed with the forceclose command. You MUST use the result file that was created with the forceclose command, otherwise it won't work. You also have to wait until the highest time lock (can be up to 2000 blocks which is more than two weeks) of all the channels has passed. If you only want to sweep channels that have the default CSV limit of 1 day, you can set the --maxcsvlimit parameter to 144.

Example command:

chantools --fromsummary results/forceclose-xxxx-yyyy.json \
  sweeptimelock
  --rootkey xprvxxxxxxxxxx \
  --publish \
  --sweepaddr bc1q.....