X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~mdw/git/tripe/blobdiff_plain/52c03a2aa0b5c3461055ca0dcf38e29f2ca88f35..18ad89136e3fe5867da9f79885db0d2eba9ac061:/doc/tripe.8 diff --git a/doc/tripe.8 b/doc/tripe.8 index b6da8d81..f5fe5bf6 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 @@ -254,19 +264,6 @@ gateway machine, has the addresses 10.0.1.1 and 200.0.1.1; site B's gateway is .B bob and has addresses 10.0.2.1 and 200.0.2.1. -.PP -This isn't quite complicated enough. Each of -.B alice -and -.B bob -needs an extra IP address which we'll use when setting up the -point-to-point link. These addresses need to be routable, at least -within the virtual private network: unfortunately, you can't just use -the same pair everywhere. We'll assign -.B alice -the point-to-point address 192.168.0.1, and -.B bob -the address 192.168.0.2. .hP 1. Install .B tripe @@ -360,19 +357,18 @@ Start the servers up. Run .RS .VS -tripectl \-slD \-S\-P23169 +tripectl \-slD \-S\-p22003 .VE on each of .B alice and .BR bob . (The -.RB ` \-P23169 ' -forces the server to use UDP port 23169: use some other number if 23169 -is inappropriate for your requirements. I chose it by reducing the -RIPEMD160 hash of -.RB ` tripe\-port\-number\e0 ' -modulo 2\*(ss16\*(se.) +.RB ` \-p22003 ' +forces the server to use UDP port 22003: use some other number if 22003 +is inappropriate for your requirements. I chose it by taking the first +16 bits of the RIPEMD160 hash of +.RB ` TrIPE '. .RE .hP 6. To get @@ -384,14 +380,12 @@ run this shell script (or one like it): .VS #! /bin/sh -tripectl add bob 200.0.2.1 23169 +tripectl add bob 200.0.2.1 22003 ifname=`tripectl ifname bob` -ifconfig $ifname \e - 192.168.0.1 \e - pointopoint 192.168.0.2 +ifconfig $ifname 10.0.1.1 pointopoint 10.0.2.1 route add -net \e 10.0.2.0 netmask 255.255.255.0 \e - gw 192.168.0.2 + gw 10.0.2.1 .VE Read .BR ifconfig (8) @@ -444,6 +438,92 @@ 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 not create SLIP tunnels 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 wedged waiting for it to +accept output. .SS "About the name" The program's name is .BR tripe , @@ -462,4 +542,4 @@ find one, please inform the author .IR "The Trivial IP Encryption Protocol" , .IR "The Wrestlers Protocol" . .SH "AUTHOR" -Mark Wooding, +Mark Wooding,