path: root/man/opennhrp.conf.5

.TH OPENNHRP.CONF 5 "27 Oct 2010" "" "OpenNHRP Documentation"

.SH NAME
opennhrp.conf \- NHRP daemon configuration file

.SH DESCRIPTION
The
.I opennhrp.conf
file contains information for the
.BR opennhrp .
.PP
This configuration file is a free-form ASCII text file. It is parsed by the
word-by-word parser built into
.BR opennhrp .
The file may contain extra whitespace, tabs and newline for formatting
purposes. Keywords and contents are case-sensitive. Comments can be marked
with a hash sign
.RB ( # )
and everything following it until newline is ignored.

.SH "DIRECTIVES"
Directives are keywords that can appear in any context of the configuration
file and they select a new context.

.PP
.BI "interface " interface-name
.RS
Marks the start of configuration for network interface
.IR interface-name .
Even if no interface specific configuration is required, the
.B interface
directive must be present to enable NHRP on that interface.
.RE

.SH "INTERFACE CONTEXT"
These configuration keywords can appear only in the interface context.

.PP
.BI "map " protocol-address[/prefix] " " nbma-address " [register] [cisco]"
.RS
Creates static peer mapping of
.I protocol-address
to
.IR nbma-address .
.PP
If the
.I prefix
parameter is present, it directs
.B opennhrp
to use this peer as a next hop server when sending Resolution Requests
matching this subnet.
.PP
The optional parameter
.I register
specifies that Registration Request should be sent to this peer on
startup.
.PP
If the statically mapped peer is running Cisco IOS, specify the
.B cisco
keyword. It is used to fix statically the Registration Request ID
so that a matching Purge Request can be sent if NBMA address has changed.
This is to work around broken IOS which requires Purge Request ID to
match the original Registration Request ID.
.RE

.BI "dynamic-map " protocol-address/prefix " " nbma-domain-name
.RS
Specifies that the NBMA addresses of the next hop servers are defined in the
domain name
.IR nbma-domain-name .
For each A record opennhrp creates a dynamic NHS entry.

Each dynamic NHS will get a peer entry with the configured network address
and the discovered NBMA address.

The first registration request is sent to the protocol broadcast address,
and the server's real protocol address is dynamically detected from the first
registration reply (requires opennhrp 0.11 or newer).

Alternatively, if
.BR peer-up
script hook can determine the protocol address from the NBMA address (e.g.
by doing an additional DNS lookup or by parsing the IPsec certificate) it can
inform this mapping via
.BR opennhrpctl "(8) " "update nbma " command.
.RE

.PP
.BI "shortcut-target " protocol-address/prefix " [holding-time " holdtime "]"
.RS
Defines an off-NBMA network prefix for which the GRE interface will act
as a gateway. This an alternative to defining local interfaces with
shortcut-destination flag.
.RE

.BR multicast " " dynamic "|" nhs
.br
.BI "multicast " protocol-address
.RS
Determines how opennhrp daemon should soft switch the multicast traffic.
Currently, multicast traffic is captured by opennhrp daemon using a packet
socket, and resent back to proper destinations. This means that multicast
packet sending is CPU intensive.

Specfying
.B nhs
makes all multicast packets to be repeated to each statically configured
next hop.
.B dynamic
instructs to forward to all peers which we have a direct connection with.
Alternatively, you can specify the directive multiple times for each
.I protocol-address
the multicast traffic should be sent to.

.B "WARNING:"
It is very easy to misconfigure multicast repeating if you have multiple
NHS:es.
.RE

.BI "holding-time " holdtime
.RS
Specifies the holding time for NHRP Registration Requests and
Resolution Replies sent from this interface or shortcut-target.
The
.I holdtime
is specified in seconds and defaults to two hours.
.RE

.BI "route-table " routetable
.RS
Specifies the kernel routing table to be monitored for outgoing routes
to this interface. This is required to do routing lookups excluding
active shortcut routes (for existing shortcut route renewal). The
default is main table.

If you use
.B table
directive in
.B zebra.conf
to put Quagga routes in alternate table, this should match with it.
.RE

.BI "cisco-authentication " secret
.RS
Enables Cisco style authentication on NHRP packets. This embeds the
.I secret
plaintext password to the outgoing NHRP packets. Incoming NHRP packets
on this interface are discarded unless the
.I secret
password is present. Maximum length of the
.I secret
is 8 characters.
.RE

.B redirect
.RS
Enable sending of Cisco style NHRP Traffic Indication packets. If
this is enabled and
.B opennhrp
detects a forwarded packet, it will send a message to the original sender
of the packet instructing it to create a direct connection with the
destination. This is basically a protocol independent equivalent of ICMP
redirect.
.RE

.B shortcut
.RS
Enable creation of shortcut routes. A received NHRP Traffic Indication
will trigger the resolution and establishment of a shortcut route.
.PP
.B IMPORTANT:
You still need to run some routing protocol or have static routes
to some hub node in your NBMA network. NHRP does not advertise routes;
it can create shortcut route only for an already routable subnet.
.RE

.B non-caching
.RS
Disables caching of peer information from forwarded NHRP Resolution
Reply packets. This can be used to reduce memory consumption on big
NBMA subnets.
.PP
NOTE: currently does not do much as caching is not implemented.
.RE

.B shortcut-destination
.RS
This instructs
.B opennhrp
to reply with authorative answers on NHRP Resolution Requests destinied
to addresses in this interface (instead of forwarding the packets). This
effectively allows the creation of shortcut routes to subnets located
on the interface.
.PP
When specified, this should be the only keyword for the interface.
.RE

.SH EXAMPLE
The following configuration file was used for testing OpenNHRP on a machine
with two ethernet network interfaces. GRE tunnel was configured with tunnel
IP 10.255.255.2/24. Configuration enables registration to hub node at
10.255.255.1 and resolution of other nodes in the subnet using that hub.
.PP
It also enables creation of shortcut routes to networks behind other
hosts (with holding-time override for the defined shortcut-target)
in our NBMA network and allows incoming shortcut routes.
.PP
.nf
interface gre1
  holding-time 3600
  map 10.255.255.1/24 192.168.200.1 register
  shortcut-target 172.16.0.0/16 holding-time 1800
  cisco-authentication secret
  shortcut
  redirect
  non-caching

interface eth1
  shortcut-destination

.fi

.SH "SEE ALSO"
.BR opennhrp (8)

.SH AUTHORS
Timo Teras <timo.teras@iki.fi>