X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~mdw/git/tripe/blobdiff_plain/52c03a2aa0b5c3461055ca0dcf38e29f2ca88f35..0e6502d3341dd870293dacc1aafea005c6dadf0d:/doc/tripe.8

diff --git a/doc/tripe.8 b/doc/tripe.8
index b6da8d81..40a5b657 100644
--- a/doc/tripe.8
+++ b/doc/tripe.8
@@ -41,6 +41,8 @@ tripe \- a simple VPN daemon
 .IR addr ]
 .RB [ \-p
 .IR port ]
+.RB [ \-n
+.IR tunnel ]
 .br
 	
 .RB [ \-U
@@ -148,6 +150,11 @@ version number to standard output and exits with status 0.
 .B "\-u, \-\-usage"
 Writes a brief usage summary to standard output and exits with status 0.
 .TP
+.B "\-\-tunnels"
+Writes to standard output a list of the configured tunnel drivers, one
+per line, and exits with status 0.  This is intended for the use of the
+start-up script, so that it can check that it will actually work.
+.TP
 .B "\-D, \-\-daemon"
 Dissociates from its terminal and starts running in the background after
 completing the initialization procedure described above.  If running as
@@ -180,6 +187,9 @@ to tunnel through the VPN.
 Use the specified UDP port for all communications with peers, rather
 than an arbitarary kernel-assigned port.
 .TP
+.BI "\-n, \-\-tunnel=" tunnel
+Use the specified tunnel driver for new peers by default.
+.TP
 .BI "\-U, \-\-setuid=" user
 Set uid to that of
 .I user
@@ -444,6 +454,91 @@ Now start
 with the
 .B \-ttripe\-ec
 option, and all should be well.
+.SS "Using other symmetric algorithms"
+The default symmetric algorithms
+.B tripe
+uses are Blowfish (by Schneier) for symmetric encryption, and RIPEMD-160
+(by Dobbertin, Bosselaers and Preneel) for hashing and as a MAC (in HMAC
+mode, designed by Bellare, Canetti and Krawczyk).  These can all be
+overridden by setting attributes on your private key, as follows.
+.TP
+.B cipher
+Names the symmetric encryption scheme to use.  The default is
+.BR blowfish\-cbc .
+.TP
+.B hash
+Names the hash function to use.  The default is
+.BR rmd160 .
+.TP
+.B mac
+Names the message authentication code to use.  The name of the MAC may
+be followed by a
+.RB ` / '
+and the desired tag length in bits.  The default is
+.IB hash \-hmac
+at half the underlying hash function's output length.
+.TP
+.B mgf
+A `mask-generation function', used in the key-exchange.  The default is
+.IB hash \-mgf
+and there's no good reason to change it.
+.SS "Using SLIP interfaces"
+Though not for the faint of heart, it is possible to get
+.B tripe
+to read and write network packets to a pair of file descriptors using
+SLIP encapsulation.  No fancy header compression of any kind is
+supported.
+.PP
+Two usage modes are supported: a preallocation system, whereby SLIP
+interfaces are created and passed to the
+.B tripe
+server at startup; and a dynamic system, where the server runs a script
+to allocate a new SLIP interface when it needs one.  It is possible to
+use a mixture of these two modes, starting
+.B tripe
+with a few preallocated interfaces and having it allocate more
+dynamically as it needs them.
+.PP
+The behaviour of
+.BR tripe 's
+SLIP driver is controlled by the
+.B TRIPE_SLIPIF
+environment variable.  The server will fail to start if this variable is
+not defined.  The variable's value is a colon-delimited list of
+preallocated interfaces, followed optionally by the filename of a script
+to run to dynamically allocate more interfaces.
+.PP
+A static allocation entry has the form
+.IR infd [ \c
+.BI , outfd \c
+.RB ] \c
+.BI = \c
+.IR ifname ,
+If the
+.I outfd
+is omitted, the same file descriptor is used for input and output.
+.PP
+The dynamic allocation script must be named by an absolute or relative
+pathname, beginning with 
+.RB ` / '
+or
+.RB ` . '.
+The server will pass the script an argument, which is the name of the
+peer for which the interface is being created.  The script should
+allocate a new SLIP interface (presumably by creating a pty pair),
+configure it appropriately, and write the interface's name to its
+standard output, followed by a newline.  It should then read and write
+SLIP packets on its stdin and stdout.  The script's stdin will be closed
+when the interface is no longer needed, and the server will attempt to
+send it a
+.B SIGTERM
+signal (though this may fail if the script runs with higher privileges
+than the server).
+.PP
+The output file descriptor should not block unless it really needs to:
+the
+.B tripe
+daemon assumes that it won't, and will get wait for it to accept output.
 .SS "About the name"
 The program's name is
 .BR tripe ,
@@ -462,4 +557,4 @@ find one, please inform the author
 .IR "The Trivial IP Encryption Protocol" ,
 .IR "The Wrestlers Protocol" .
 .SH "AUTHOR"
-Mark Wooding, <mdw@nsict.org>
+Mark Wooding, <mdw@distorted.org.uk>