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DTCPS(8)               DragonFly System Manager's Manual              DTCPS(8)


NAME

     dtcps - Dynamic Tunnel Configuration Protocol daemon


SYNOPSIS

     dtcps [-cdDoU] [-b udp-port] [-g address] [-i interfaces]
           [-I udp-interface] [-p port] [prefix]


DESCRIPTION

     dtcps implements Dynamic Tunnel Configuration Protocol (DTCP for short)
     proposed by Trumpet.  This listens to IPv4 TCP port 20200 (or port
     specified by port), for DTCP client connections.

     dtcps will use APOP password database file (pop.auth) as password
     database.

     Clients requesting tunnel typed "tunnelonly" will get simple IPv6-over-
     IPv4 tunnel.  No global address will be assigned to the configured tunnel
     link.  It is up to administrators to assign global IPv6 address to the
     client host, or to the client network.  Static assignment by hand or use
     of router advertisement packet should do the trick.  Use of router
     renumbering protocol may be a candidate.

     Clients requesting tunnel typed "network" aka "tunnelroute" will get
     IPv6-over-IPv4 tunnel with appropriate static route for the connected
     user installed.  This can be used for prefix delegation.  The routes for
     each user is specified in /usr/local/etc/routetable.  No global address
     will be assigned to the configured tunnel link.

     If prefix argument is specified, dtcps will accept tunnel request for
     "host" tunnel type.  The tunnel type needs a pair of temporary global
     IPv6 address for the configured tunnel link, like 3ffe:ffff:ffff:ffff::5
     and 3ffe:ffff:ffff:ffff::6.  The address pair will be assigned from
     specified prefix.  Prefixlen for the temporary global address will be
     128, and it will be computed by using interface number of tunnel
     interface.

     dtcps assumes all gif interfaces are available to use.  If -i interfaces
     argument is specified, dtcps will use only specified interfaces.
     interfaces accepts regular expression.

     If interfaces is not regular expression but an exact interface name,
     dtcps acts as interface cloning mode which dtcps creates and deletes
     interfaces appropriately.  In this mode, interfaces means a lower
     interface to be created.

     With interface cloning mode, if -o is specified, dtcps creates the
     interfaces appropriately, but prevents destroying and reuses created
     interfaces.

     If -U is specified, dtcps accepts request for an IPv6 over an UDP/IPv4
     tunnel as well.  The lower value of an UDP port is specified by -b, and
     its default is "4028".  dtcps assumes all netgraph interfaces are
     available to use.  If -I interface argument is specified, dtcps creates
     and deletes interfaces appropriately.  interface means a lower interface
     to be created.  An IPv6 over an UDP/IPv4 tunnel requires Netgraph.
     (Experimental)

     You may want to use specific interface for certain user.  You can specify
     the interface to 3rd field of /usr/local/etc/routetable.  It can be used
     not only for tunnel typed "network" but also "tunnelonly" and "host".  If
     you don't want to assign prefix for your user, you can specify `-' for
     2nd field.

     -D prevents dtcps from daemonizing on invocation.

     -c disables interface cloning mode.

     -d puts dtcps into debug mode.

     In normal situation, you cannot serv DTCP from behind your NAT box.
     However, you may serv DTCP in such situation with the help of NAT box.
     In such case, you need to respond actual global address to a client.  -g
     address is specified, dtcps responds the address as the actuall IPv4
     global address of your NAT box.


RETURN VALUES

     dtcps will exit with positive value on errors.


FILES

     /usr/local/etc/routetable
               This file is used for "network" tunnel type, and maps between
               the user and the assigned IPv6 prefix for the user.  The format
               is a space separated list of the user name, the assigned IPv6
               prefix and the interface.  The IPv6 prefix is a pair of IPv6
               address and prefixlen like addr/prefixlen.  Multiple IPv6
               prefixes can be specified by using comma as separator.  The
               interface is optional, and if interface is specified, the
               interface is used for the user.
     /usr/local/etc/pop.auth
               The APOP password database.
     /var/run/dtcps.pid
               Contains the process ID of the dtcps listening for connections.
               The content of this file is not sensitive; it can be world-
               readable.


SEE ALSO

     daemon(3), gif(4), dtcpauth(8), dtcpc(8), gifconfig(8), ifconfig(8),
     qpopauth(8)


HISTORY

     The dtcps command first appeared in WIDE/KAME IPv6 protocol stack kit.

     "network" tunnel type and other useful facilities were added by Hajimu
     UMEMOTO <ume@mahoroba.org>.


BUGS

     DTCP needs to keep TCP connection between server and client.  Therefore,
     maximum number of client served by single dtcps will be bounded by the
     maximum number of filehandle allowed to a process (100 or so).

     dtcps invokes several external commands, like ifconfig(8) and
     gifconfig(8).  Command search path must be configured properly before
     invoking dtcps.

     dtcps requires qpopauth shipped with qpopper to maintain APOP password
     database.  There is dtcpauth for this purpose.  Though the ability of
     dtcpauth is still limitted, you can use it for the replacement for
     qpopauth.

     dtcps was written in Ruby. :-)

                                January 6, 2006

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