.\"	$NetBSD: faithd.8,v 1.12 2000/09/14 00:36:10 itojun Exp $
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.Dd May 17, 1998
.Dt FAITHD 8
.Os
.Sh NAME
.Nm faithd
.Nd FAITH IPv6/v4 translator daemon
.Sh SYNOPSIS
.Nm
.Op Fl dp
.Ar service
.Op Ar serverpath Op Ar serverargs
.Nm ""
.Sh DESCRIPTION
.Nm
provides IPv6-to-IPv4 TCP relay.
.Nm
must be used on an IPv4/v6 dual stack router.
.Pp
When
.Nm
receives
.Tn TCPv6
traffic,
.Nm
will relay the
.Tn TCPv6
traffic to
.Tn TCPv4 .
Destination for relayed
.Tn TCPv4
connection will be determined by the last 4 octets of the original
.Tn IPv6
destination.
For example, if
.Li 3ffe:0501:4819:ffff::
is reserved for
.Nm Ns ,
and the
.Tn TCPv6
destination address is
.Li 3ffe:0501:4819:ffff::0a01:0101 ,
the traffic will be relayed to IPv4 destination
.Li 10.1.1.1 .
.Pp
To use
.Nm
translation service,
an IPv6 address prefix must be reserved for mapping IPv4 addresses into.
Kernel must be properly configured to route all the TCP connection
toward the reserved IPv6 address prefix into the
.Xr faith 4
pseudo interface, by using
.Xr route 8
command.
Also,
.Xr sysctl 8
should be used to configure
.Dv net.inet6.ip6.keepfaith
to
.Dv 1 .
.Pp
The router must be configured to capture all the TCP traffic
toward reserved
.Tn IPv6
address prefix, by using
.Xr route 8
and
.Xr sysctl 8
commands.
.Ss Daemon mode
When
.Nm
is invoked as a standalone program,
.Nm
will daemonize itself.
.Nm
will listen to
.Tn TCPv6
port
.Ar service .
If
.Tn TCPv6
traffic to port
.Ar service
is found, it relays the connection.
.Pp
Since
.Nm
listens to TCP port
.Ar service ,
it is not possible to run local TCP daemons for port
.Ar service
on the router, using
.Xr inetd 8
or other standard mechanisms.
By specifying
.Ar serverpath
to
.Nm Ns ,
you can run local daemons on the router.
.Nm
will invoke local daemon at
.Ar serverpath
if the destination address is local interface address,
and will perform translation to IPv4 TCP in other cases.
You can also specify
.Ar serverargs
for the arguments for the local daemon.
.Pp
If
.Fl d
is given, debugging information will be generated using
.Xr syslog 3 .
If
.Fl p
is given,
.Nm
will use privileged TCP port number as source port,
for IPv4 TCP connection toward final destination.
For relaying
.Xr ftp 1
and
.Xr rlogin 1 ,
.Fl p
is not necessary as special program code is supplied.
.Pp
.Nm
will relay both normal and out-of-band TCP data.
It is capable of emulating TCP half close as well.
.Nm
includes special support for protocols used by
.Xr ftp 1
and
.Xr rlogin 1 .
When translating FTP protocol,
.Nm
translates network level addresses in
.Li PORT/LPRT/EPRT
and
.Li PASV/LPSV/EPSV
commands.
For RLOGIN protocol,
.Nm
will relay back connection from
.Xr rlogind 8
on the server to
.Xr rlogin 1
on client.
.Pp
Inactive sessions will be disconnected in 30 minutes,
to avoid stale sessions from chewing up resources.
This may be inappropriate for some of the services
.Pq should this be configurable? .
.Ss inetd mode
When
.Nm
is invoked via
.Xr inetd 8 ,
.Nm
will handle connection passed from standard input.
If it the connection endpoint is in the reserved IPv6 address prefix.
.Nm
will relay the connection.
Otherwise,
.Nm
will invoke service-specific daemon like
.Xr telnetd 8 ,
by using the command argument passed from
.Xr inetd 8 .
.Pp
.Nm
determines operation mode by the local TCP port number,
and enables special protocol handling whenever necessary/possible.
For example, if
.Nm
is invoked via
.Xr inetd 8
on FTP port, it will operate as a FTP relay.
.Pp
The operation mode requires special support for
.Nm
in
.Xr inetd 8 .
.Sh EXAMPLES
Before invoking
.Nm Ns ,
.Xr faith 4
interface has to be configured properly.
.Bd -literal -offset
# sysctl -w net.inet6.ip6.accept_rtadv=0
# sysctl -w net.inet6.ip6.forwarding=1
# sysctl -w net.inet6.ip6.keepfaith=1
# ifconfig faith0 up
# route add -inet6 3ffe:501:4819:ffff:: -prefixlen 96 ::1
# route change -inet6 3ffe:501:4819:ffff:: -prefixlen 96 -ifp faith0
.Ed
.Ss Daemon mode samples
To translate
.Li telnet
service, and provide no local telnet service, invoke
.Nm
as either of the following:
.Bd -literal -offset
# faithd
# faithd telnet
.Ed
.Pp
If you would like to provide local telnet service via
.Xr telnetd 8
on
.Pa /usr/libexec/telnetd ,
use the following command line:
.Bd -literal -offset
# faithd telnet /usr/libexec/telnetd telnetd
.Ed
.Pp
If you would like to pass extra arguments to the local daemon:
.Bd -literal -offset
# faithd ftpd /usr/libexec/ftpd ftpd -l
.Ed
.Pp
Here are some other examples.
You may need
.Fl p
to translate rsh/rlogin services.
.Bd -literal -offset
# faithd sshd
# faithd login /usr/libexec/rlogin rlogind
# faithd shell /usr/libexec/rshd rshd
.Ed
.Pp
However, you should be careful when translating rlogin or rsh
connections. See
.Sx SECURITY NOTICE
for more details.
.Ss inetd mode samples
Add the following lines into
.Xr inetd.conf 5 .
.\"Syntax may vary depending upon your operating system.
.Bd -literal -offset
telnet  stream  faith/tcp6  nowait  root  faithd  telnetd
ftp     stream  faith/tcp6  nowait  root  faithd  ftpd -l
ssh     stream  faith/tcp6  nowait  root  faithd  /usr/pkg/bin/sshd -i
.Ed
.Pp
.Xr inetd 8
will open listening sockets with enabling kernel TCP relay support.
Whenever connection comes in,
.Nm
will be invoked by
.Xr inetd 8 .
If it the connection endpoint is in the reserved IPv6 address prefix.
.Nm
will relay the connection.
Otherwise,
.Nm
will invoke service-specific daemon like
.Xr telnetd 8 .
.Sh EXIT STATUS
.Nm
exits with
.Dv EXIT_SUCCESS
.Pq 0
on success, and
.Dv EXIT_FAILURE
.Pq 1
on error.
.Sh SEE ALSO
.Xr faith 4 ,
.Xr route 8 ,
.Xr sysctl 8
.Rs
.%A Jun-ichiro itojun Hagino
.%A Kazu Yamamoto
.%T "An IPv6-to-IPv4 transport relay translator"
.%R internet draft
.%N draft-ietf-ngtrans-tcpudp-relay-01.txt
.%O work in progress material
.Re
.Sh SECURITY NOTICE
It is very insecure to use
.Xr rhosts 5
and other IP-address based authentication, for connections relayed by
.Nm
.Pq and any other TCP relaying services .
.Pp
.Nm
itself does not implement access controls, as
it intends to implement transparent TCP relay services.
Administrators are advised to filter packets based on IPv6 address.
IPv6 destination address can be limited by
carefully configuring routing entries that points to
.Xr faith 4 ,
using
.Xr route 8 .
IPv6 source address needs to be filtered by using packet filters.
Documents listed in
.Sx SEE ALSO
have more discussions on this topic.
Under inetd mode of operation, you can limit the connection source by using
.Xr hosts.allow 5 .
.\"
.Sh HISTORY
The
.Nm
command first appeared in WIDE Hydrangea IPv6 protocol stack kit.