[B.A.T.M.A.N.] [PATCHv2] alfred: Add explanation how to run alfred as non-root user

[Sven Eckelmann <sven@narfation.org>]

Reported-by: MK <mailing.m1@kkk-web.de>
Signed-off-by: Sven Eckelmann <sven@narfation.org>
---
v2:
 - fix typo 'directly' -> 'directory'

 README | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/README b/README
index 90a99de..2bb4f9b 100644
--- a/README
+++ b/README
@@ -256,6 +256,32 @@ To get JSON formatted output, use:
 
 See gpsd_json(5) for documentation of the tpv object. 
 
+Running alfred as non-root user
+-------------------------------
+
+Alfred currently requires special capabilities and access rights to work
+correctly. The user root is normally the only user having these
+capabilities/rights on a standard Linux system.
+
+Operations requiring special capabilities:
+
+ * bind to device
+ * creating the unix socket
+ * accessing the debugfs filesystem
+
+The first operation can still be executed when the admin grants the special
+capability CAP_NET_RAW to anyone executing the alfred binary. The unix socket
+can also be moved using the parameter '-u' to a different directory which can
+be accessed by the user.
+
+ $ sudo setcap cap_net_raw+ep alfred
+ $ ./alfred -u alfred.sock -i eth0
+
+The user running alfred must still be in a group which is allowed to access
+/sys/kernel/debugfs to correctly choose best neighbors for communication.
+It is possible (but not recommended) to disable the neighbor
+selection/prioritization using the parameter '-b none'.
+
 License
 -------
 
-- 
2.1.4