AcceptLND

AcceptLND is a channel requests management tool based on policies for LND.

Usage

acceptlnd [-config CONFIG] [-debug] [-version]

Parameters:
  -config          Path to the configuration file (default: "acceptlnd.yml")
  -debug           Enable debug level logging
  -version         Print the current version

Installation

Download the binary from the Releases page, use docker or compile it yourself.

Docker

docker build -t acceptlnd .
# The configuration, certificate and macaroon must be mounted into the container.
# The paths specified in the configuration file can be absolute or relative to the mount path.
docker run --network=host -v <config_files_mount> acceptlnd <flags>

Build from source

Requires Go 1.18+ installed

git clone https://github.com/aftermath2/acceptlnd
cd acceptlnd
go build -o acceptlnd -ldflags="-s -w" .

Configuration

The configuration file can be passed as a flag (-config="<path>") when executing the binary, the default value is acceptlnd.yml.

Configuration schema:

Key	Type	Required	Description
rpc_address	string	✔	LND GRPC address (host:port)
certificate_path	string	✔	Path to LND's TLS certificate
macaroon_path	string	✔	Path to the macaroon file. See macaroon
policies	[]Policy	✖	Set of policies to enforce

Macaroon

AcceptLND needs a macaroon to communicate with the LND instance to manage channel requests.

Although admin.macaroon can be used, it is recommended baking a fine-grained macaroon that gives AcceptLND access just to the RPC methods it uses. To bake it, execute:

lncli bakemacaroon uri:/lnrpc.Lightning/ChannelAcceptor uri:/lnrpc.Lightning/GetInfo uri:/lnrpc.Lightning/GetNodeInfo --save_to acceptlnd.macaroon

Once created, specify its path in the macaroon_path field of the configuration file, it can be relative or absolute.

Policy

Policies define a set of requirements that must be met for a request to be accepted. A configuration may have an unlimited number of policies, they are evaluated from top to bottom.

A policy would only be enforced if its conditions are satisfied, or if it has no conditions.

Name	Type	Description
conditions	Conditions	Set of conditions that must be met to enforce the policies
reject_all	boolean	Reject all channel requests
whitelist	[]string	List of nodes public keys whose requests will be accepted
blacklist	[]string	List of nodes public keys whose requests will be rejected
reject_private_channels	boolean	Whether private channels should be rejected
reject_zero_conf_channels	boolean	Whether to reject zero confirmation channels
request	Request	Parameters related to the channel opening request
node	Node	Parameters related to the channel initiator

Here's a simple example:

policies:
  -
    conditions:
      is_private: true
    request:
      channel_capacity:
        min: 2_000_000

This policy only applies to private channels and will reject those that have a capacity lower than 2 million sats.

Note

The denomination used in all the numbers is satoshis.

More examples can be found at /examples.

Conditions

Conditions are used to evaluate policies conditionally. When used, all of them must resolve to true or the policy is skipped.

They are defined in the configuration exactly the same way policies are, only a few fields change.

Name	Type	Description
whitelist	[]string	List of nodes public keys to which policies should be applied
blacklist	[]string	List of nodes public keys to which policies should not be applied
is_private	boolean	Match private channels
wants_zero_conf	boolean	Match zero confirmation channels
request	Request	Parameters related to the channel opening request
node	Node	Parameters related to the initiator node

Request

Parameters related to the channel opening request.

Name	Type	Description
channel_capacity	range	Requested channel size
channel_reserve	range	Requested channel reserve
push_amount	range	Pushed amount of sats
csv_delay	range	Requested CSV delay
max_accepted_htlcs	range	The total number of incoming HTLC's that the initiator will accept
min_htlc	range	The smallest HTLC in millisatoshis that the initiator will accept
max_value_in_flight	range	The maximum amount of coins in millisatoshis that can be pending in the channel
dust_limit	range	The dust limit of the initiator's commitment transaction
commitment_types	[]int	Accepted channel commitment types. See lnrpc.CommitmentTypes

Node

Parameters related to the node that is initiating the channel.

Name	Type	Description
capacity	range	Peer's node capacity
hybrid	boolean	Whether the peer will be required to be hybrid
feature_flags	[]int	Feature flags the peer node must know. Check out lnrpc.FeatureBit
Channels	Channels	Initiator node channels

Channels

Parameters related to the initiator node's channels.

Name	Type	Description
number	range	Peer's number of channels
zero_base_fees	boolean	Whether the peer's channels must all have zero base fees
capacity	stat_range	Channels size
block_height	stat_range	Channels block height
time_lock_delta	stat_range	Channels time lock delta
min_htlc	stat_range	Channels minimum HTLC
max_htlc	stat_range	Channels maximum HTLC
last_update_diff	stat_range	Channels last update difference to the time of the request (seconds)
together	range	Number of channels that the host node and initiator node have together
incoming_fee_rates	stat_range	Channels incoming fee rates
outgoing_fee_rates	stat_range	Channels outgoing fee rates
incoming_base_fees	stat_range	Channels incoming base fees
outgoing_base_fees	stat_range	Channels outgoing base fees
outgoing_disabled	stat_range	Number of outgoing disabled channels. The value type is float and should be between 0 and 1
incoming_disabled	stat_range	Number of incoming disabled channels. The value type is float and should be between 0 and 1

Note

Outgoing refers to the channel value from the initiator's node side, incoming to the value corresponding to the initiator node peer side.

For instance, let's say Bob wants to open a channel with us and he already has one with Charlie. Bob has a base fee of 0 sats and Charlie has a base fee of 1 sat. In this case, the outgoing base fee is 0 sats (Bob's side) and the incoming base fee is 1 sat (Charlie's side).

Range

A range may have a minimum value, a maximum value or both defined. All values are in satoshis.

Min and Max are inclusive, they include the value assigned: [Min, Max].

Example

request:
  channel_capacity:
    min: 2_000_000
    max: 50_000_000

Statistic range (stat_range)

Statistic ranges work just like ranges but they compare values against the node's data set after being aggregated using an operation.

Example

node:
  channels:
    outgoing_fee_rates:
      operation: median
      min: 0
      max: 100

Operations

• mean (default): average of a list of numbers.
• median: middle value in a list ordered from smallest to largest.
• mode: most frequently occurring value on a list.
• range: difference between the biggest and the smallest number.