alfred(8) Almighty Lightweight Fact Remote Exchange Daemon


alfred [options]


alfred is a user space daemon for distributing arbitrary local information over the mesh/network in a decentralized fashion. This data can be anything which appears to be useful - originally designed to replace the batman-adv visualization (vis), you may distribute hostnames, phone books, administration information, DNS information, the local weather forecast ...

alfred runs as daemon in the background of the system. A user may insert information by using the alfred binary on the command line, or use special programs to communicate with alfred (done via unix sockets). alfred then takes care of distributing the local information to other alfred servers on other nodes. This is done via IPv6 link-local multicast, and does not require any configuration. A user can request data from alfred, and will receive the information available from all alfred servers in the network.


-v, --version
Print the version
-h, --help
Display a brief help message.
-u, --unix-path path
path to unix socket used for client-server communication.


-s, --set-data data-type
Sets new data to distribute from stdin for the supplied data type (0-255).

Note that 0 - 63 are reserved (please send an e-mail to the authors if you want to register a datatype), and can not be used on the commandline. Information must be periodically written again to alfred, otherwise it will timeout and alfred will forget about it (after 10 minutes).

-r, --request data-type
Collect data from the network and prints it on the network
-d, --verbose
Show extra information in the data output
-V, --req-version version
Specify the data version set for -s

Skipping the parameter entirely has the same effect as setting the parameter to 0 ('-V 0').

-M, --modeswitch mode
    Switch daemon to mode master
    Switch daemon to mode slave
-I, --change-interface interface
Change the alfred server to use the new interface(s)


-i, --interface face
Specify the interface (or comma separated list of interfaces) to listen on
-b batmanif
Specify the batman-adv interface configured on the system (default: bat0). Use 'none' to disable the batman-adv based best server selection.

The -b option is optional, and only needed if you run alfred on a batman-adv interface not called bat0, or if you don't use batman-adv at all (use '-b none'). In this case, alfred will still work but will not be able to find the best next master server based on metrics.

-m, --master
Start up the daemon in master mode, which accepts data from slaves and syncs it with other masters.

alfred servers may either run as master or slave in the network. Masters will announce their status via broadcast, so that slaves can find them. Slaves will then send their data to their nearest master (based on TQ). Masters will exchange their data (which they have received from slaves or got on their own) with other masters. By using masters and slaves, overhead can be reduced while still keeping redundancy (by having multiple masters). Obviously, at least one master must be present in the network to let any data exchange happen. Also having all nodes in master mode is possible (for maximum decentrality and overhead).

-c, --update-command command
Specify command to execute on data change. It will be called with data-type list as arguments.


Start an alfred server listening on bridge br0 (assuming that this bridge includes the batman interface bat0):
alfred -i br0 -m

Send data to the alfred server and store it under id 65:
cat /etc/hostname | alfred -s 65

Retrieve all data stored as id 65 from all connected alfred servers:
alfred -r 65

     { "fe:f1:00:00:01:01", "OpenWRT-node-1\x0a" },
     { "fe:f1:00:00:02:01", "OpenWRT-node-2\x0a" },
     { "fe:f1:00:00:03:01", "OpenWRT-node-3\x0a" },


alfred was written by Simon Wunderlich <[email protected]> and Sven Eckelmann <[email protected]>.

This manual page was written by Simon Wunderlich <[email protected]> and Sven Eckelmann <[email protected]>.