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.
Globaloptionsprotocol-groupgroup
This specifies the link-local multicast address to be used by the protocol, and is equivalent to
the command-line option -m.
protocol-portport
This specifies the UDP port number to be used by the protocol, and is equivalent to the command-
line option -p.
kernel-prioritypriority
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-duplicatespriority
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.
debuglevel
This specifies the debugging level, and is equivalent to the command-line option -d.
local-portport
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-readwriteport
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-pathpath
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-readwritepath
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-tabletable
This specifies the kernel routing table to use for routes inserted by babeld, and is equivalent to
the command-line option -t.
import-tabletable
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.
kernel-check-intervalseconds
This specifies the interval between two kernel routing table dumps. The default is 300s (5
minutes). This may be set to 0 in order to never perform periodic kernel dumps.
shutdown-delay-msmilliseconds
During shutdown we first notify neighbours of our imminent shutdown by sending route retractions,
wait for the specified number of milliseconds and then flush kernel routes. This ensures any
inflight traffic is still properly forwarded. You may want to ensure the delay is appropriate for
the maximum delay path in your network. Setting this to zero is permissible.
link-detect {true|false}
This specifies whether to use carrier sense for determining interface availability, and is
equivalent to the command-line option -l.
smoothing-half-lifeseconds
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, and it is assumed that
enabling forwarding, disabling redirects and disabling the reverse-path filter is performed by
other means. This can be useful when running in environments where system permissions prevent
setting kernel parameters, for instance without root permissions or inside a Linux container.
router-idid
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-filefilename
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-filefilename
This specifies the name of the file used to log random messages to, and is equivalent to the
command-line option -L.
pid-filefilename
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-rule-prioritypriority
This specifies smallest (highest) rule priority used with source-specific routes. The default is
100.
keyididtype {hmac-sha256|blake2s128} valuevalue
Configure a key for use with the key interface option. The type is one of hmac-sha256 or
blake2s128. The value is a hexadecimal string (up to 64 bytes for hmac-sha256, up to 32 bytes for
blake2s128).
Interfaceconfiguration
An interface is configured by a line with the following format:
interfacename [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.
rxcostcost
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.
hello-intervalinterval
This defines the interval between hello packets sent on this interface. The default is specified
with the -h and -H command-line flags.
update-intervalinterval
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.
unicast {true|false}
Send multiple copies of TLVs other than Hellos to all neighbours rather than sending a single
multicast packet. The default is false.
rfc6126-compatible {true|false}
Disable some features that are incompatible with RFC 6126 (the older version of the Babel
protocol), such as source-specific routing and RTT estimation over unicast. The default is false.
rtt-decaydecay
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-minrtt
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-maxrtt
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-penaltycost
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.
v4-via-v6 {true|false}
Whether to announce IPv4 routes through this interface even when there is no IPv4 address. The
default depends on the kernel version.
probe-mtu {true|false}
Pad all packets containing a Hello TLV to the MTU and disable fragmentation. This will avoid
establishing adjacencies across links with a mis-configured MTU, at the cost of slightly higher
network usage.
keyid Enable HMAC security on this interface, and use the key id.
accept-bad-signatures {true|false}
Accept packets with no signature or an incorrect signature. This only has an effect if a key was
configured on an interface. The default is false.
Filteringrules
A filtering rule is defined by a single line with the following format:
filterselector... actionFilter 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
ipprefix
This entry only applies to routes in the given prefix.
eqplen
This entry only applies to routes with a prefix length equal to plen.
leplen
This entry only applies to routes with a prefix length less or equal to plen.
geplen
This entry only applies to routes with a prefix length greater or equal to plen.
src-ipprefix
This entry only applies to routes with a source prefix in the given prefix.
src-eqplen
This entry only applies to routes with a source prefix length equal to plen.
src-leplen
This entry only applies to routes with a source prefix length less or equal to plen.
src-geplen
This entry only applies to routes with a source prefix length greater or equal to plen.
neighaddress
This entry only applies to routes learned from a neighbour with link-local address address.
idid This entry only applies to routes originated by a router with router-id id.
protop
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.
ifinterface
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.
metricvalue
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-prefixprefix
For a redistribute filter, set the source prefix of this route to prefix.
tabletable
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.
pref-srcip
Specify the preferred source address to use with this route. Only useful in an install filter.
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.
Install Now
PNG Icons