Need a command that lists all connections to/from a given mongos or mongod

The currentOp(true) command does not always return a list of all open connections to and from a given mongos or mongod. This is especially true on a mongos where the command instead calls currentOp() on the primary nodes of each shard and merges the results together.

I need a reliable way to determine what connections are currently open to and from a given mongos or mongod server. This list should correspond to the connection count from db.serverStatus().connections.