DTCPS(8)

NAME
dtcps - Dynamic Tunnel Configuration Protocol daemon

SYNOPSIS
dtcps [-dD] [-g address] [-i interfaces] [-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.

-D prevents dtcps from daemonizing on invocation.

-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 and the assigned IPv6 prefix. 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.
/usr/local/etc/qpopper/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), dtcpc(8), gifconfig(8), qpopauth(8)

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

“network” tunnel type and other useful facilities are 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 logger(1), 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.

dtcps was written in Ruby. :-)