Provided by: babeld_1.8.3-1_amd64 bug

NAME

       babeld - ad-hoc network routing daemon

SYNOPSIS

       babeld option...  [ -- ] interface...

DESCRIPTION

       Babel  is a loop-avoiding distance-vector routing protocol roughly based on DSDV and AODV,
       but with provisions for link cost estimation  and  redistribution  of  routes  from  other
       routing protocols.

       While  it  is  optimised  for  wireless mesh networks, Babel will also work efficiently on
       wired networks.

OPTIONS

       -V     Display babeld's version and quit.

       -m multicast-address
              Specify the link-local multicast address to be used by the protocol.   The  default
              is ff02:0:0:0:0:0:1:6.

       -p port
              Specify the UDP port number to be used by the protocol.  The default is 6696.

       -S state-file
              Set  the  name  of  the  file  used  for  preserving  long-term information between
              invocations of the babeld daemon.  If this file is deleted, the daemon will run  in
              passive  mode for 3 minutes when it is next started (see -P below), and other hosts
              might initially ignore it.  The default is /var/lib/babel-state.

       -h hello-interval
              Specify the interval in seconds at  which  scheduled  hello  packets  are  sent  on
              wireless interfaces.  The default is 4 seconds.

       -H wired-hello-interval
              Specify  the interval in seconds at which scheduled hello packets are sent on wired
              interfaces.  The default is 4 seconds.

       -z kind [,factor]
              Enable diversity-sensitive routing.  The value kind defines the diversity algorithm
              used,  and  can  be  one  of  0  (no diversity), 1 (per-interface diversity with no
              memory), 2 (per-channel diversity with no memory), or 3 (per-channel diversity with
              memory).  The value factor specifies by how much the cost of non-interfering routes
              is multiplied, in units of 1/256; the default is 128 (i.e. division by 2).

       -M half-time
              Specify the half-time in seconds  of  the  exponential  decay  used  for  smoothing
              metrics  for  performing  route  selection;  the  value  0 disables smoothing.  The
              default is 4s.

       -k priority
              Specify the priority value used  when  installing  routes  into  the  kernel.   The
              default is 0.

       -A priority
              Allow  duplicating external routes when their kernel priority is at least priority.
              Do not use this option unless you  know  what  you  are  doing,  as  it  can  cause
              persistent route flapping.

       -l     Use IFF_RUNNING (carrier sense) when determining interface availability.

       -w     Don't  optimise  wired  links, assume all interfaces are wireless unless explicitly
              overridden in the configuration file.

       -s     Do not perform split-horizon processing on wired interfaces.  Split-horizon is  not
              performed on wireless interfaces.

       -r     Use  a  random router-id.  The default is to use persistent router-ids derived from
              the MAC address of the first interface, which is easier to debug and more  reliably
              prevents  routing  loops  but  may sometimes cause a node to be unreachable for 120
              seconds just after boot.

       -u     Do not flush unfeasible (useless) routes.  This is useful in order to announce more
              information to a front-end (see -g).

       -d level
              Debug level.  A value of 1 requests a routing table dump at every iteration through
              the daemon's main loop.  A value of 2 additionally requests tracing  every  message
              sent  or  received.   A  value of 3 additionally dumps all interactions with the OS
              kernel.  The default is 0.

       -g port, -g path
              Set up a local configuration server on port port or at path in read-only mode.  The
              protocol is described in the section Local Configuration Protocol below.

       -G port, -G path
              Set  up  a  local  configuration server on port port or at path in read-write mode.
              This allows any local user to change babeld's configuration, and may therefore be a
              security issue.

       -t table
              Use the given kernel routing table for routes inserted by babeld.

       -T table
              Export  routes  from the given kernel routing table. This can be specified multiple
              times in order to export routes from more than one table.

       -c filename
              Specify the name of the configuration file.  This flag  can  be  repeated  multiple
              times.  The default is /etc/babeld.conf.

       -C statement
              Specify a configuration statement directly on the command line.

       -D     Daemonise at startup.

       -L logfile
              Specify  a  file  to  log  random ``how do you do?'' messages to.  This defaults to
              standard error if not daemonising, and to /var/log/babeld.log otherwise.

       -I pidfile
              Specify a file to write our process id to, use no  pidfile  if  set  to  the  empty
              string.  The default is /var/run/babeld.pid.

       interface...
              The list of interfaces on which the protocol should operate.

CONFIGURATION FILE FORMAT

       The  configuration file is a sequence of lines each of which specifies a global option, an
       interface specification or a filtering rule.  Comments  are  introduced  by  an  octothorp
       ``#'' and terminate at the end of the line.

   Global options
       protocol-group group
              This  specifies the link-local multicast address to be used by the protocol, and is
              equivalent to the command-line option -m.

       protocol-port port
              This specifies the UDP port number to be used by the protocol, and is equivalent to
              the command-line option -p.

       kernel-priority priority
              This  specifies the priority value used when installing routes into the kernel, and
              is equivalent to the command-line option -k.

       reflect-kernel-metric {true|false}
              Reflect route metrics as kernel  priorities.   The  priority  effectively  used  is
              kernel-priority + metric.

       allow-duplicates priority
              This  allows  duplicating  external  routes  when their kernel priority is at least
              priority.  Do not use this option unless you know what you are  doing,  as  it  can
              cause persistent route flapping.

       random-id {true|false}
              This specifies whether to use a random router-id, and is equivalent to the command-
              line option -r.

       ipv6-subtrees {true|false}
              This specifies whether to use native source-specific IPv6  forwarding  rather  than
              multiple  routing  tables.   The  default  is chosen automatically depending on the
              kernel version.

       debug level
              This specifies the debugging level, and is equivalent to  the  command-line  option
              -d.

       local-port port
              This  specifies  the  TCP  port  on which babeld will listen for connections from a
              configuration client in read-only mode,  and  is  equivalent  to  the  command-line
              option -g.

       local-port-readwrite port
              This  specifies  the  TCP  port  on which babeld will listen for connections from a
              configuration client in read-write mode, and  is  equivalent  to  the  command-line
              option  -G.   This  allows any local user to change babeld's configuration, and may
              therefore be a security issue.

       local-path path
              This specifies the filesystem path to a socket on  which  babeld  will  listen  for
              connections from a configuration client in read-only mode, and is equivalent to the
              command-line option -g.

       local-path-readwrite path
              This specifies the filesystem path to a socket on  which  babeld  will  listen  for
              connections  from  a  configuration client in read-write mode, and is equivalent to
              the command-line option -G.  Any user with write access to that socket will be able
              to change babeld's configuration.

       export-table table
              This  specifies  the kernel routing table to use for routes inserted by babeld, and
              is equivalent to the command-line option -t.

       import-table table
              This specifies a kernel routing  table  from  which  routes  are  redistributed  by
              babeld,  and  can  be  specified  multiple times with a cumulative effect.  This is
              equivalent to the command-line option -T.

       link-detect {true|false}
              This specifies whether to use carrier sense for determining interface availability,
              and is equivalent to the command-line option -l.

       diversity {true|false|kind}
              This  specifies  the diversity algorithm to use; true is equivalent to kind 3.  The
              default is false (do not use any diversity algorithm).

       diversity-factor factor
              This specifies by how much the cost of non-interfering routes should be multiplied,
              in units of 1/256.  The default is 128 (division by 2).

       smoothing-half-life seconds
              This specifies the half-life in seconds of the exponential decay used for smoothing
              metrics for performing route selection,  and  is  equivalent  to  the  command-line
              option -M.

       daemonise {true|false}
              This  specifies  whether to daemonize at startup, and is equivalent to the command-
              line option -D.

       skip-kernel-setup {true|false}
              If this flag is set, no kernel (sysctl) setup is performed on startup. This can  be
              useful when running in environments where system permissions prevent setting kernel
              parameters, for instance inside a Linux container.

       router-id id
              Specify the router-id explicitly, as a modified EUI-64 or a MAC-48 address.  If two
              nodes  have  the  same  router-id,  bad  things will happen.  Don't use this option
              unless you know what you are doing.

       state-file filename
              This specifies the name of the  file  used  for  preserving  long-term  information
              between  invocations  of  the  babeld daemon, and is equivalent to the command-line
              option -S.

       log-file filename
              This specifies the name of the  file  used  to  log  random  messages  to,  and  is
              equivalent to the command-line option -L.

       pid-file filename
              This  specifies the name of the file to which babeld writes out its process id, and
              is equivalent to the command-line option -I.

       first-table-number table
              This specifies the index of the first routing  table  to  use  for  source-specific
              routes.  The default is 10.

       first-rule-priority priority
              This  specifies  smallest (highest) rule priority used with source-specific routes.
              The default is 100.

   Interface configuration
       An interface is configured by a line with the following format:

              interface name [parameter...]

       where name is the name of the interface (something like eth0).  The default  value  of  an
       interface parameter can be specified changed by a line of the form

              default [parameter...]

       Each parameter can be one of:

       type {auto|wired|wireless|tunnel}

              The default is auto unless the -w command-line flag was specified.

       link-quality {true|false|auto}
              This  specifies  whether  link  quality  estimation  should  be  performed  on this
              interface.   The  default  is  to  perform  link  quality  estimation  on  wireless
              interfaces only.

       split-horizon {true|false|auto}
              This  specifies whether to perform split-horizon processing on this interface.  The
              default is to perform split-horizon processing on on wired interfaces,  unless  the
              -s flag was set.

       rxcost cost
              This  defines  the  cost  of  receiving  frames  on the given interface under ideal
              conditions (no packet loss); how this relates to the actual cost used for computing
              metrics  of  routes  going  through  this interface depends on whether link quality
              estimation is being done.  The default is 256 if the interface is wireless, and  96
              otherwise.

       channel channel
              Sets  the  channel for this interface.  The value channel can be either an integer,
              or one of the strings interfering or noninterfering.  The default is to  autodetect
              the   channel   number  for  wireless  interfaces,  and  noninterfering  for  other
              interfaces.

       faraway {true|false}
              This specifies whether the network is "far away", in the sense that networks behind
              it  don't interfere with networks in front of it.  By default, networks are not far
              away.

       hello-interval interval
              This defines the interval between  hello  packets  sent  on  this  interface.   The
              default is specified with the -h and -H command-line flags.

       update-interval interval
              This  defines the interval between full routing table dumps sent on this interface;
              since Babel uses triggered updates and doesn't count to infinity, this can  be  set
              to  a  fairly large value, unless significant packet loss is expected.  The default
              is four times the hello interval.

       enable-timestamps {true|false}
              Enable sending timestamps with each Hello and IHU message in order to  compute  RTT
              values.  The default is true for tunnel interfaces, and false otherwise.

       rtt-decay decay
              This  specifies the decay factor for the exponential moving average of RTT samples,
              in units of 1/256.  Must be between 1 and 256, inclusive.   Higher  values  discard
              old samples faster.  The default is 42.

       rtt-min rtt
              This  specifies  the  minimum RTT, in milliseconds, starting from which we increase
              the cost to a neighbour. The additional cost is linear in  (rtt  -  rtt-min).   The
              default is 10 ms.

       rtt-max rtt
              This  specifies the maximum RTT, in milliseconds, above which we don't increase the
              cost to a neighbour. The default is 120 ms.

       max-rtt-penalty cost
              This specifies the maximum cost added to a neighbour because of RTT, i.e. when  the
              RTT is higher or equal than rtt-max.  The default is 96 if the interface is of type
              tunnel, and 0 otherwise.

   Filtering rules
       A filtering rule is defined by a single line with the following format:

              filter selector...  action

       Filter specifies the filter to which this entry will be  added,  and  can  be  one  of  in
       (applied  to  routes  learned  from Babel neighbours), out (applied to routes announced to
       Babel neighbours), redistribute (applied to routes  redistributed  from  the  kernel),  or
       install (applied to routes installed into the kernel).

       Each selector specifies the conditions under which the given statement matches.  It can be
       one of

       ip prefix
              This entry only applies to routes in the given prefix.

       eq plen
              This entry only applies to routes with a prefix length equal to plen.

       le plen
              This entry only applies to routes with a prefix length less or equal to plen.

       ge plen
              This entry only applies to routes with a prefix length greater or equal to plen.

       src-ip prefix
              This entry only applies to routes with a source prefix in the given prefix.

       src-eq plen
              This entry only applies to routes with a source prefix length equal to plen.

       src-le plen
              This entry only applies to routes with a source prefix  length  less  or  equal  to
              plen.

       src-ge plen
              This  entry  only applies to routes with a source prefix length greater or equal to
              plen.

       neigh address
              This entry only applies to routes learned from a neighbour with link-local  address
              address.

       id id  This entry only applies to routes originated by a router with router-id id.

       proto p
              This entry only applies to kernel routes with kernel protocol number p.  If neither
              proto nor local is specified, this entry applies to  all  non-local  kernel  routes
              with a protocol different from "boot".

       local  This entry only applies to local addresses.

       if interface
              For  an input filter, this specifies the interface over which the route is learned.
              For an output filter, this  specifies  the  interface  over  which  this  route  is
              advertised.   For a redistribute statement, this specifies the interface over which
              the route forwards packets.

       Action specifies the action to be taken when this entry matches.  It can have one  of  the
       following values:

       allow  Allow  this  route, without changing its metric (or setting its metric to 0 in case
              of a redistribute filter).

       deny   Ignore this route.

       metric value
              For an input or output filter, allow this route  after  increasing  its  metric  by
              value.  For a redistribute filter, redistribute this route with metric value.

       src-prefix prefix
              For a redistribute filter, set the source prefix of this route to prefix.

       table table
              In an install filter, specify the kernel routing table to use.  For source-specific
              routes, this only works reliably for IPv6, and only when ipv6-subtrees is true.

       If action is not specified, it defaults to allow.

       By default, babeld redistributes all local addresses, and no other routes.   In  order  to
       make sure that only the routes you specify are redistributed, you should include the line

              redistribute local deny

       as the last line in your configuration file.

LOCAL CONFIGURATION INTERFACE

       If  babeld  is  invoked with the flag -g, it accepts TCP connections from local clients on
       the given port and address ::1 (the IPv6 localhost address), or on the  given  UNIX-domain
       socket  path if the argument starts with ‘/’.  When a client connects, babeld replies with
       BABEL followed with the supported version of the local configuration  protocol  (currently
       1.0).  This is followed with a number of informational lines (version etc.), terminated by
       ok.  The client can then send requests, one per line.  To  each  request,  babeld  replies
       with one or more lines of data terminated by one of ok, no, or bad.

       The following requests are currently defined:

       · any configuration file directive, including interface;

       · flush interface;

       · dump;

       · monitor and unmonitor;

       · quit.

EXAMPLES

       You can participate in a Babel network by simply running

              # babeld wlan0

       where wlan0 is the name of your wireless interface.

       In order to gateway between multiple interfaces, just list them all on the command line:

              # babeld wlan0 eth0 sit1

       On an access point, you'll probably want to redistribute some external routes into Babel:

              # babeld \
                  -C 'redistribute metric 256' \
                  wlan0

       or, if you want to constrain the routes that you redistribute,

              # babeld \
                  -C 'redistribute proto 11 ip ::/0 le 64 metric 256' \
                  -C 'redistribute proto 11 ip 0.0.0.0/0 le 24 metric 256' \
                  wlan0

   Source-specific routing
       If  your  want  to  redistribute kernel routes as source-specific to the network, with the
       2001:DB8:0:1::/64 prefix:

              redistribute src-prefix 2001:DB8:0:1::/64

       For more information about source-specific routing, please see

              Matthieu Boutier and Juliusz Chroboczek.  Source-sensitive routing.  In Proc.  IFIP
              Networking 2015.  2015.

       available online at

              http://arxiv.org/pdf/1403.0445v4.pdf

FILES

       /etc/babeld.conf
              The default location of the configuration file.

       /var/lib/babel-state
              The default location of the file storing long-term state.

       /var/run/babeld.pid
              The default location of the pid file.

       /var/log/babeld.log
              The default location of the log file.

SIGNALS

       SIGUSR1
              Dump Babel's routing tables to standard output or to the log file.

       SIGUSR2
              Check interfaces and kernel routes right now, then reopen the log file.

SECURITY

       Babel  is  a  completely  insecure protocol: any attacker able to inject IP packets with a
       link-local source address can disrupt the protocol's operation.  This is no different from
       unsecured neighbour discovery or ARP.

       Usage  of  the  -G  flag  allows  any  user  logged  on  the local host to change babeld's
       configuration.

       Since Babel uses link-local IPv6 packets only, there is no need  to  update  firewalls  to
       allow  forwarding  of  Babel  protocol  packets.   If  local  filtering is being done, UDP
       datagrams to the port used by the protocol should  be  allowed.   As  Babel  uses  unicast
       packets  in  some  cases,  it  is  not  enough  to  just allow packets destined to Babel's
       multicast address.

SEE ALSO

       routed(8), route6d(8), zebra(8), ahcpd(8).

AUTHOR

       Juliusz Chroboczek.

                                                                                        BABELD(8)