Using the tinc command, an administrator of an existing VPN can generate
invitations for new nodes. The invitation is a small URL that can easily
be copy&pasted into email or live chat. Another person can have tinc
automatically setup the necessary configuration files and exchange keys
with the server, by only using the invitation URL.
The invitation protocol uses temporary ECDSA keys. The invitation URL
consists of the hostname and port of the server, a hash of the server's
temporary ECDSA key and a cookie. When the client wants to accept an
invitation, it also creates a temporary ECDSA key, connects to the server
and says it wants to accept an invitation. Both sides exchange their
temporary keys. The client verifies that the server's key matches the hash
in the invitation URL. After setting up an SPTPS connection using the
temporary keys, the client gives the cookie to the server. If the cookie
is valid, the server sends the client an invitation file containing the
client's new name and a copy of the server's host config file. If everything
is ok, the client will generate a long-term ECDSA key and send it to the
server, which will add it to a new host config file for the client.
The invitation protocol currently allows multiple host config files to be
send from the server to the client. However, the client filters out
most configuration variables for its own host configuration file. In
particular, it only accepts Name, Mode, Broadcast, ConnectTo, Subnet and
AutoConnect. Also, at the moment no tinc-up script is generated.
When an invitation has succesfully been accepted, the client needs to start
the tinc daemon manually.
This gets rid of the rest of the symbolic links. However, as a consequence, the
crypto header files have now moved to src/, and can no longer contain
library-specific declarations. Therefore, cipher_t, digest_t, ecdh_t, ecdsa_t
and rsa_t are now all opaque types, and only pointers to those types can be
used.
There are several reasons for this:
- MacOS/X doesn't support polling the tap device using kqueue, requiring a
workaround to fall back to select().
- On Windows only sockets are properly handled, therefore tinc uses a second
thread that does a blocking ReadFile() on the TAP-Win32/64 device. However,
this does not mix well with libevent.
- Libevent, event just the core, is quite large, and although it is easy to get
and install on many platforms, it can be a burden.
- Libev is more lightweight and seems technically superior, but it doesn't
abstract away all the platform differences (for example, async events are not
supported on Windows).
When set to a non-zero value, tinc will try to maintain exactly that number of
meta connections to other nodes. If there are not enough connections, it will
periodically try to set up an outgoing connection to a random node. If there
are too many connections, it will periodically try to remove an outgoing
connection.
When starting tincd, tincctl now strips non-options from the command line, and
sets argv[0] to the name of the tincd command instead of copying its own
command name.
When stopping a running tincd, tincctl now waits for it to terminate.
Internally, tinc maintains a directed graph of the meta connections between
nodes. However, this causes graphviz to draw two lines between nodes, which is
not always desirable. The "dump graph" command now defaults to dumping an
undirected graph, the "dump digraph" command will dump a directed graph.
This allows tincctl to receive log messages from a running tincd,
independent of what is logged to syslog or to file. Tincctl can receive
debug messages with an arbitrary level.
This allows administrators who frequently want to work with one tinc
network to omit the -n option. Since the NETNAME variable is set by
tincd when executing scripts, this makes it slightly easier to use
tincctl from within scripts.
sometimes argv[0] will have directory-less name (when the
command is started by shell searching in $PATH for example).
For tincctl start we want the same rules to run tincd as for
tincctl itself (having full path is better but if shell does
not provide one we've no other choice). Previous code tried
to run ./tincd in this case, which is obviously wrong.
This is a fix for the previous commit.
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
For tincctl start, run tincd from dirname($0) not SBINDIR -
this allows painless alternative directory installation and
running from build directory too.
Also while at it, pass the rest of command line to tincd, not
only options before "start" argument. This way it's possible
to pass options to tincd like this:
tincctl -n net start -- -d 1 -R -U tincuser ...
And also add missing newline at the end of error message there.
Signed-Off-By: Michael Tokarev <mjt@tls.msk.ru>
The generate-keys command now generates both an RSA and an ECDSA keypair,
but one can generate-rsa-keys or generate-ecdsa-keys to just generate one type.
The pid is now written first, so that a version 1.0.x tincd can be used to stop
a running version 1.1 tincd. Getsockname() is used to determine the address of
the first listening socket, so that tincctl can connect to the local tincd even
if AddressFamily = ipv6, or if BindToAddress or BindToInterface is used.
This would allow tincctl to connect to a remote tincd, or to a local tincd that
isn't listening on localhost, for example if it is using the BindToInterface or
BindToAddress options.
The control socket code was completely different from how meta connections are
handled, resulting in lots of extra code to handle requests. Also, not every
operating system has UNIX sockets, so we have to resort to another type of
sockets or pipes for those anyway. To reduce code duplication and make control
sockets work the same on all platforms, we now just connect to the TCP port
where tincd is already listening on.
To authenticate, the program that wants to control a running tinc daemon must
send the contents of a cookie file. The cookie is a random 256 bits number that
is regenerated every time tincd starts. The cookie file should only be readable
by the same user that can start a tincd.
Instead of the binary-ish protocol previously used, we now use an ASCII
protocol similar to that of the meta connections, but this can still change.
UNIX domain sockets, of course, don't exist on Windows. For now, when compiling
tinc in a MinGW environment, try to use a TCP socket bound to localhost as an
alternative.
This provides reasonable security even on Solaris. The sysadmin is
responsible for securing the control socket's ancestors from the
grandparent on.
We could add a cryptographic handshake later if desired.
