wsdd implements a Web Service Discovery host daemon. This enables (Samba) hosts, like your local NAS device, to be found by Web Service Discovery Clients like Windows.
Since NetBIOS discovery is not supported by Windows anymore, wsdd makes hosts to appear in Windows again using the Web Service Discovery method. This is beneficial for devices running Samba, like NAS or file sharing servers on your local network.
With Windows 10 version 1511, support for SMBv1 and thus NetBIOS device discovery was disabled by default. Depending on the actual edition, later versions of Windows starting from version 1709 ("Fall Creators Update") do not allow the installation of the SMBv1 client anymore. This causes hosts running Samba not to be listed in the Explorer's "Network (Neighborhood)" views. While there is no connectivity problem and Samba will still run fine, users might want to have their Samba hosts to be listed by Windows automatically.
You may ask: What about Samba itself, shouldn't this functionality be included in Samba!? Yes, maybe. However, using Samba as file sharing service is still possible even if the host running Samba is not listed in the Network Neighborhood. You can still connect using the host name (given that name resolution works) or IP address. So you can have network drives and use shared folders as well. In addition, there is a patch lurking around in the Samba bug tracker since 2015. So it may happen that this feature gets integrated into Samba at some time in the future.
wsdd requires Python 3 only. It runs on Linux and FreeBSD. Other Unixes, such as OpenBSD or NetBSD, might work as well but were not tested.
Although Samba is not strictly required by wsdd itself, it makes sense to run wsdd only on hosts with a running Samba daemon. Note that the OpenRC/Gentoo init script depends on the Samba service.
Installation and Usage
No installation steps are required. Just place the wsdd.py file anywhere you
want to, rename it to wsdd, and run it from there. The init scripts/unit files
assume that wsdd is installed under
case of FreeBSD. There are no configuration files. No special privileges are
required to run wsdd, so it is advisable to run the service as an unprivileged
user such as nobody.
etc directory of the repo contains sample configuration files for
different init(1) systems, namely FreeBSD's rc.d, Gentoo's openrc, and systemd
which is used in most contemporary Linux distros. Those files may be used as
templates for their actual usage. They are likely to require adjustments to the
actual distribution/installation where they are to be used.
Both incoming and outgoing multicast traffic on port 3702 must be allowed. For
IPv4, the multicast address is
126.96.36.199, for IPv6 the link local SSDP
multicast address (
fe02::c) is used.
Incoming TCP traffic (and related outgoing traffic) on port 5357 must be allowed.
Specify on which interfaces wsdd will be listening on. If no interfaces are specified, all interfaces are used. The loop-back interface is never used, even when it was explicitly specified. For interfaces with IPv6 addresses, only link-local addresses will be used for announcing the host on the network. This option can be provided multiple times in order to use more than interface (but no all).
Set the hop limit for multicast packets. The default is 1 which should prevent packets from leaving the local network segment.
The WSD specification requires a device to have a unique address that is stable across reboots or changes in networks. In the context of the standard, it is assumed that this is something like a serial number. wsdd uses the UUID version 5 with the DNS namespace and the host name of the local machine as inputs. Thus, the host name should be stable and not be modified, e.g. by DHCP. However, if you want wsdd to use a specific UUID you can use this option.
Assume that the host running wsdd joined an ADS domain. This will make wsdd report the host being a domain member. It disables workgroup membership reporting. The (provided) hostname is automatically converted to lower case. Use the
-poption to change this behavior.
Override the host name wsdd uses during discovery. By default the machine's host name is used (look at hostname(1)). Only the host name part of a possible FQDN will be used in the default case.
By default wsdd reports the host is a member of a workgroup rather than a domain (use the -d/--domain option to override this). With -w/--workgroup the default workgroup name can be changed. The default work group name is WORKGROUP. The (provided) hostname is automatically converted to upper case. Use the
-poption to change this behavior.
Do not service http requests of the WSD protocol. This option is intended for debugging purposes where another process may handle the Get messages.
Additively increase verbosity of the log output. A single occurrence of -v/--verbose sets the log level to INFO. More -v options set the log level to DEBUG.
Use a shorter logging format that only includes the level and message. This is useful in cases where the logging mechanism, like systemd on Linux, automatically prepend a date and process name plus ID to the log message.
Preserve the hostname as it is. Without this option, the hostname is converted as follows. For workgroup environments (see
-w) the hostname is made upper case by default. Vice versa it is made lower case for usage in domains (see
Restrict to the given address family. If both options are specified no addreses will be available and wsdd will exit.
handle traffic on eth0 only, but only with IPv6 addresses
wsdd -i eth0 -6
wsdd --interface eth0 --ipv6only
set the Workgroup according to smb.conf and be verbose
SMB_GROUP=$(grep -i '^\s*workgroup\s*=' smb.conf | cut -f2 -d= | tr -d '[:blank:]')
wsdd -v -w $SMB_GROUP
(Read the source for more details)
For each specified (or all) network interfaces, except for loopback, an UDP multicast socket for message reception, an UDP send socket for replying messages using unicast, and a listening TCP socket is created. This is done for both the IPv4 and the IPv6 address family if not configured otherwise by the command line arguments (see above). Upon startup a Hello message is sent. When wsdd terminates due to a SIGTERM signal or keyboard interrupt, a graceful shutdown is performed by sending a Bye message. I/O multiplexing is used to handle network traffic of the different sockets within a single process.
wsdd does not implement any security feature, e.g. by using TLS for the http service. This is because wsdd's intended usage is within private, i.e. home, LANs. The Hello message contains the hosts transport address, i.e. the IP address which speeds up discovery (avoids Resolve message).
Using only IPv6 on FreeBSD
If wsdd is running on FreeBSD using IPv6 only, the host running wsdd may not be reliably discovered. The reason appears to be that Windows is not always able to connect to the HTTP service for unknown reasons. As a workaround, run wsdd with IPv4 only.
Usage with NATs
Do not use wssd on interfaces that are affected by NAT. According to the
standard, the ResolveMatch messages emitted by wsdd, contain the IP address
("transport address" in standard parlance) of the interface(s) the application
has been bound to into. When such messages are retrieved by a client (Windows
hosts, e.g.) they are unlikely to be able to connect to the provided address
which has been subject to NAT. To avoid this issue, use the
option to bind wsdd to interfaces not affected by NAT.
If tunnel/bridge interfaces like those created by OpenVPN or Docker exist, they
may interfere with wsdd if executed without providing an interface that it
should bind to (so it binds to all). In such cases, the wsdd hosts appears after
wsdd has been started but it disappears when an update of the Network view in
Windows Explorer is forced, either by refreshing the view or by a reboot of the
Windows machine. To solve this issue, the interface that is connected to the
network on which the host should be announced needs to be specified with the
-i/--interface option. This prevents the usage of the tunnel/bridge
Background: Tunnel/bridge interfaces may cause Resolve requests from Windows hosts to be delivered to wsdd multiple times,´i.e. duplicates of such request are created. If wsdd receives such a request first from a tunnel/bridge it uses the transport address (IP address) of that interface and sends the response via unicast. Further duplicates are not processed due to the duplicate message detection which is based on message UUIDs. The Windows host which receives the response appears to detect a mismatch between the transport address in the ResolveMatch message (which is the tunnel/bridge address) and the IP of the sending host/interface (LAN IP, e.g.). Subsequently, the wsdd host is ignored by Windows.
Contributions are welcome. Please ensure PEP8 compliance when submitting patches or pull requests.
The code is licensed under the MIT license.
Thanks to Jose M. Prieto and his colleague Tobias Waldvogel who wrote the mentioned patch for Samba to provide WSD and LLMNR support. A look at their patch set made cross-checking the WSD messages easier.
References and Further Reading
...and the standards referenced within the above.
Documentation and Discussion on Windows/WSD
Discussion at tenforums.com about missing hosts in network Note: Solutions suggest to go back to SMBv1 protocol which is deprecated! Do not follow this advice.
Meanwhile, there is a C implementation of a WSD daemon, named wsdd2. This one also includes LLMNR which wsdd lacks. However, LLMNR may not be required depending on the actual network/name resolution setup.
OpenWRT includes the above C implementation. So OpenWRT users are unlikely to need an installation of wsdd.
FreeNAS appears to have wsdd included in the distribution.