During the init command, tinc changed the umask to 077 when writing the public
and private key files, to prevent the temporary copies from being world
readable. However, subsequently created files would therefore also be
unreadable for others. Now we don't change the umask anymore, therefore
allowing the user to choose whether the files are world readable or not by
setting the umask as desired. The private key files are still made unreadable
for others of course. Temporary files now inherit the permissions of the
original, and the tinc-up script's permissions now also honour the umask.
Tinc now strictly limits incoming connections from the same host to 1 per
second. For incoming connections from multiple hosts short bursts of incoming
connections are allowed (by default 100), but on average also only 1 connection
per second is allowed.
When an incoming connection exceeds the limit, tinc will keep the connection in
a tarpit; the connection will be kept open but it is ignored completely. Only
one connection is in a tarpit at a time to limit the number of useless open
connections.
Some options can take an optional argument. However, in this case GNU getopt
requires that the optional argument is right next to the option without
whitespace inbetween. If there is whitespace, getopt will treat it as a
non-option argument, but tincd ignored those without a warning. Now tincd will
allow optional arguments with whitespace inbetween, and will give an error when
it encounters any other non-option arguments.
The tinc binary now requires that all options for itself are given before the
command.
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.
