NAME
ahcpd - ad-hoc configuration daemon
SYNOPSIS
ahcpd option... [ -- ] interface...
DESCRIPTION
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:
mode server|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.
SEE ALSO
dhcpcd(8), dhclient(8), babel(8), olsrd(8), ntpd(8), The Ad-Hoc
Configuration Protocol.
AUTHOR
Juliusz Chroboczek.