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kadnode(1) - P2P name resolver daemon

SYNOPSIS

kadnode [--announce <domain>] [--daemon] [...]

kadnode-ctl [...]

DESCRIPTION

KadNode is a small P2P DNS resolver. It supports authentication based on x509 certificates and hexadecimal public key queries.

JOIN THE SWARM

KadNode needs to know at least one active peer to join / bootstrap into the swarm. There are three ways to archieve this:

  1. Provide one or more peers to the command line arguments. These could be public BitTorrent trackers, or other KadNode instances:
kadnode --peer bttracker.debian.org --peer 192.168.1.1
  1. Ping a peer using the KadNode console if present:
kadnode-ctl ping bttracker.debian.org
  1. Use the local peer discovery feature. Just start KadNode and it will try to discover other KadNode nodes in the local network.

Also provide a --peerfile argument to let KadNode load its peerlist on startup and store on every 24h and shutdown. This ensures successful bootstrapping on next startup.

AUTHENTICATION

KadNode provides two authentication schemes. One works via x509 certificates and TLS. The other one uses raw secret/public keys and is hence called bob.

Via TLS

Typically there are two KadNode instances involved.

One node announces a domain, e.g. mynode.p2p. The other node looks for the IP address of the announcing node. Authentication happens via TLS, which in turn uses X509 certificates.

kadnode --announce mynode.p2p --tls-server-cert mynode.crt,mynode.key

As an alternative, ownerhip can be proven using a HTTPS server running on the same host. In this case, KadNode itself does not need certificates, but needs to announce the HTTPS port:

kadnode --announce mynode.p2p:443

The other node doing the lookup for mynode.p2p needs to have access to the root certificate that has been used to sign mynode.crt. These can be a common web browsers certificates:

kadnode --tls-client-cert /usr/share/ca-certificates/mozilla

Own certificates authorities can be created and used, of course.

Note: --announce is optional in many cases as domains from certificate and key files are announced automatically.

Via BOB

First create an elliptic curve secret key file:

kadnode --bob-create-key mysecretkey.pem
Generating secp256r1 key pair...
Public key: c492192ac20144ed2a43d57e7239f5ef5f6bb418a51600980e55ff565cc916a4
Wrote secret key to mysecretkey.pem

Now make the secret key load on KadNode startup:

kadnode --bob-load-key mysecretkey.pem

Any reachable node can now resolve c492192ac20144ed2a43d57e7239f5ef5f6bb418a51600980e55ff565cc916a4.p2p to the IP address of the announcing host. There is no need to share any additional information beforehand.

No Authentication

KadNode also allows to just lookup a hexdecimal string and to get IP addresses as return. This is the plain use of the DHT. The hexadecimal string will be cut down or filled up with zeros internally to fit the size the DHT uses (currently 20 bytes).

OPTIONS

  • --announce domain[:port]
    Announce a domain and an optional port via the DHT.
    This option may occur multiple times.

  • --peerfile file
    Import peers for bootstrapping and write good peers
    to this file every 24 hours and on shutdown.

  • --user name
    Change the UUID after start.

  • --port port
    Bind the DHT to this port.
    Default: 6881

  • --config file
    Provide a configuration file with one command line
    option on each line. Comments start after '#'.

  • --ifname interface
    Bind to this specific interface.

  • --fwd-disable
    Disable UPnP/NAT-PMP to forward router ports.

  • --daemon
    Run in background.

  • --query-tld domain
    Top level domain used to filter queries to be resolved by KadNode.
    Default: p2p

  • --verbosity level
    Verbosity level quiet, verbose or debug.
    Default: verbose

  • --pidfile file-path
    Write process pid to a file.

  • --lpd-disable
    Disable Local Peer Discovery (LPD).

  • --cmd-disable-stdin
    Disable the local control interface.

  • --cmd-path path
    Bind the remote control interface to a unix socket.
    Default: /tmp/kadnode/kadnode_cmd.sock

  • --dns-port port
    Bind the DNS server interface to this local port.
    Default: 3535

  • --dns-server address
    IP address of an external DNS server. Enables DNS proxy mode.
    Default: disabled

  • --dns-proxy-enable
    Enable DNS proxy mode. Uses /etc/resolv.conf by default.

  • --dns-proxy-server ip-address
    Use IP address of an external DNS server instead of /etc/resolv.conf.

  • --nss-path path
    Bind the "Name Service Switch" to a unix socket.
    Default: /tmp/kadnode/kadnode_nss.sock

  • --tls-client-cert path
    Path to file or folder of CA root certificates.
    This option may occur multiple times.

  • --tls-server-cert path,path
    Add a comma separated server certificate file path and key file path.
    This option may occur multiple times.
    Example: kadnode.crt,kadnode.key

  • --bob-create-key file
    Write a new secp256r1 secret key in PEM format to the file.
    The public key will be printed to the terminal before exit.

  • --bob-load-key file
    Read a secret key in PEM format and announce the public key.
    This option may occur multiple times.

  • --ipv4, -4, --ipv6, -6
    Enable IPv4 or IPv6 only mode for the DHT.
    Default: IPv4+IPv6

  • -h, --help
    Print the list of accepted options.

  • -v, --version
    Print program version and included features.

KadNode Console Commands

When not started in background, KadNode accepts a variety of commands from standard input.

  • status
    Print the node id, the number of known nodes / searches / stored hashes and more.

  • lookup domain
    Lookup the IP addresses of all nodes that claim to satisfy the domain.
    The first call will start the search.

  • announce [domain[:port] [minutes]]
    Announce that this instance is associated with a domain
    and an optional port. The default port is random (but not equal 0).
    A missing minutes argument trigger a single announcement. Negative minutes
    last for the entire runtime. Otherwise the lifetime is set minutes into the future.
    No arguments will announce all identifiers at once.

  • import addr
    Send a ping to another KadNode instance to establish a connection.

  • export
    Print a few good nodes.

  • list [blacklist|buckets|constants|forwardings|results|searches|storage|values]
    List various internal data structures.

  • blacklist addr
    Blacklist a specific IP address.

KadNode External Console

KadNode allows a limited set of commands to be send from any user from other consoles.

kadnode-ctl [-p path] [status|lookup|announce|import|export|blacklist]

  • -p path
    Unix socket used to connect to the command shell of a local KadNode instance (Default: /tmp/kadnode.sock).

  • -h
    Print this help.

Name Service Switch (NSS)

Kadnode can intercept system wide DNS lookups via NSS. This is need to be able to use kadnode links in the web browser or for command line tools like ssh. For this, /etc/nsswitch.conf need to be configured:

  • Copy libnss_kadnode.so.2 to /lib/. Other libnss_*.so files are likely to be there as well.
  • Edit /etc/nsswitch.conf to include kadnode in the hosts: line before entry dns:
    • hosts: kadnode dns

Automatic Port Forwarding

If KadNode runs on a computer in a private network, it will try to establish a port forwarding for the DHT port and ports used for announcements. Port forwarding only works if UPnP/NAT-PMP is compiled into KadNode and is supported by the gateway/router. This is useful to make a local service (e.g. a web server) reachable from the Internet without the need to configure port forwardings manually.

LICENSE

MIT/X11