AHCP is a configuration protocol that can replace DHCP on networks without
transitive connectivity, such as mesh networks.
OPTIONS
-m multicast-address
Speficy the link-local multicast address to be used by AHCP.
-p port
Specify the UDP port number to be used by AHCP.
-n
Operate as a forwarder: participate in the flooding protocol, but don't
actually perform any configuration.
-4
Only attempt to configure IPv4 addresses.
-6
Only attempt to configure IPv6 addresses.
-N
Do not configure DNS.
-t time
Specify the time, in seconds, for which leases are requested. The default
is slightly over one hour.
-s script
Specify the configuration script to run. The default is
/etc/ahcp/ahcp-config.sh.
-d level
Set the debug level to
level
(default 1).
-i filename
Specify the filename containing this host's unique id. The default is
/var/lib/ahcp-unique-id.
If it doesn't exist, it will be created by
ahcpd.
-c filename
Specify the name of the configuration file. 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/ahcpd.log
otherwise.
-I pidfile
Specify a file to write our process id to.
CONFIGURATION FILE FORMAT
The configuration is a sequence of lines, each of which starts with
one of the keywords below. Blank lines are ignored. Comments are
introduced with an octothorp
``#''
and terminate at the end of the line.
The following keywords are recognised:
modeserver|client|forwarder
Specifies whether the daemon operates as a server, a client, or
a forwarder. If omitted, the default is to operate as a client, unless
the
-n
flag is present on the command line. If present, this must be the first
line in the configuration file.
prefix prefix
Specifies either a prefix to use for configuring clients. This keyword is
only valid in server configurations, and may be specified twice, once for
IPv4 and once for IPv6.
name-server address
Specifies the address of a DNS server to configure clients with. This
keyword is only valid in server configurations, and may be repeated
multiple times.
ntp-server address
Specifies the address of an NTP server to configure clients with. This
keyword is only valid in server configurations, and may be repeated
multiple times.
FILES
/var/lib/ahcp-unique-id
An 8-byte long file containing this host's unique id. If it doesn't exist,
a new unique id will be generated from an interface's MAC address.
/etc/ahcp/ahcp-config.sh
The script that performs the actual configuration. It will be passed one
argument, which is either
start
or
stop.
/etc/ahcp/ahcp-local.sh
If this is an executable script, it will be called by
ahcp-config.sh
just after configuring or deconfiguring. It will be passed one
argument, which is either
start
or
stop.
SIGNALS
SIGUSR1
Print
ahcpd's
status to standard output or to the log file.
SIGUSR2
Check all interfaces for status changes, then reopen the log file.
NOTES
Since the AHCP protocol is designed for mesh networks, it doesn't have any
provisions for setting routing parameters such as a default gateway, the
IPv4 network mask and the IPv6 list of on-link prefixes; these are expected
to be provided by a full-fledged routing protocol for mesh nodes, and by
router advertisements for ordinary nodes.
The AHCP server should use NTP to synchronise its clock. If a server
instance of
ahcpd
doesn't detect time synchronisation, it will only give out leases for
a short period of time, and be extremely conservative about releasing them.
Note that an SNTP client is not enough ---
ahcpd
actually checks with the kernel for time synchronisation, so real NTP is
necessary.