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proxystore.p2p.nat

Tools for getting the NAT type using STUN.

This module is a wrapper around the tools provided by pystun3.

NatType

Bases: Enum

NAT type.

Learn more about NAT types at https://en.wikipedia.org/wiki/Network_address_translation.

OpenInternet class-attribute instance-attribute 

OpenInternet = 'Open Internet (No NAT)'

Host is not behind a NAT.

FullCone class-attribute instance-attribute 

FullCone = 'Full-cone NAT'

Host is behind a full-cone NAT.

SymmetricUDPFirewall class-attribute instance-attribute 

SymmetricUDPFirewall = 'Symmetric UDP Firewall NAT'

Host is behind a symmetric UDP firewall.

RestrictedCone class-attribute instance-attribute 

RestrictedCone = 'Restricted-cone NAT'

Host is behind a restricted-cone NAT.

PortRestrictedCone class-attribute instance-attribute 

PortRestrictedCone = 'Port Restricted-cone NAT'

Host is behind a port-restricted-cone NAT.

Symmetric class-attribute instance-attribute 

Symmetric = 'Symmetric NAT'

Host is behind a symmetric NAT.

Result

Bases: NamedTuple

Result of NAT type check.

Attributes:

  • nat_type (NatType) –

    Enum type of the found NAT this host is behind.

  • external_ip (str) –

    External IP of this host.

  • external_port (int) –

    External port of this host.

check_nat 

check_nat(
    source_ip: str = "0.0.0.0", source_port: int = 54320
) -> Result

Check the NAT type this host is behind.

This function uses the STUN protocol (RFC 3489) to discover the presence and type of the NAT between this host and the open Internet.

Parameters:

  • source_ip (str, default: '0.0.0.0' ) –

    Address to bind to.

  • source_port (int, default: 54320 ) –

    Port to listen on.

Returns:

  • Result –

    Result containing the NAT type and external IP/port of the host.

Raises:

  • RuntimeError –

    if no STUN servers return a response or if the hosts IP or port changed during the STUN process.

Source code in proxystore/p2p/nat.py 
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def check_nat(
    source_ip: str = '0.0.0.0',
    source_port: int = 54320,
) -> Result:
    """Check the NAT type this host is behind.

    This function uses the STUN protocol (RFC 3489) to discover the
    presence and type of the NAT between this host and the open Internet.

    Args:
        source_ip: Address to bind to.
        source_port: Port to listen on.

    Returns:
        Result containing the NAT type and external IP/port of the host.

    Raises:
        RuntimeError: if no STUN servers return a response or if the hosts
            IP or port changed during the STUN process.
    """
    with socket.socket(socket.AF_INET, socket.SOCK_DGRAM) as s:
        s.settimeout(2)
        s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
        s.bind((source_ip, source_port))

        for stun_server in _STUN_SERVERS:
            stun_server_address, stun_server_port = stun_server.split(':')

            _nat_type, external = stun.get_nat_type(
                s,
                source_ip,
                source_port,
                stun_host=stun_server_address,
                stun_port=int(stun_server_port),
            )

            try:
                nat_type = NatType._from_str(_nat_type)
            except RuntimeError:
                pass
            else:
                break
        else:
            raise RuntimeError(
                'No STUN servers returned a valid response. '
                'Enable debug level logging for more details.',
            )

    return Result(nat_type, external['ExternalIP'], external['ExternalPort'])

check_nat_and_log 

check_nat_and_log(
    source_ip: str = "0.0.0.0", source_port: int = 54320
) -> None

Check the NAT type this host is behind and log the results.

Wrapper around check_nat() that logs the results rather than return them.

Parameters:

  • source_ip (str, default: '0.0.0.0' ) –

    Address to bind to.

  • source_port (int, default: 54320 ) –

    Port to listen on.

Source code in proxystore/p2p/nat.py 
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def check_nat_and_log(
    source_ip: str = '0.0.0.0',
    source_port: int = 54320,
) -> None:
    """Check the NAT type this host is behind and log the results.

    Wrapper around [`check_nat()`][proxystore.p2p.nat.check_nat] that logs
    the results rather than return them.

    Args:
        source_ip: Address to bind to.
        source_port: Port to listen on.
    """
    logger.info('Checking NAT type. This may take a moment...')
    try:
        nat_type, external_ip, external_port = check_nat(
            source_ip=source_ip,
            source_port=source_port,
        )
    except Exception as e:
        logger.error(f'Failed to determine NAT type: {e}')
    else:
        logger.info(f'NAT Type:       {nat_type.value}')
        logger.info(f'External IP:    {external_ip}')
        logger.info(f'External Port:  {external_port}')

        if nat_type == NatType.Symmetric:
            logger.warning(
                'NAT traversal (e.g., hole-punching) does not work reliably '
                'across Symmetric NATs or poorly behaved legacy NATs. '
                'Peer-to-peer methods may not work.',
            )
        else:
            logger.info(
                'NAT traversal for peer-to-peer methods (e.g., hole-punching) '
                'is likely to work. (NAT traversal does not work reliably '
                'across symmetric NATs or poorly behaved legacy NATs.)',
            )