The Broadcast option can be used to cause tinc to drop all broadcast and
multicast packets. This option might be expanded in the future to selectively
allow only some broadcast packet types.
The code introduced in commit 41a05f59ba is not
needed anymore, since tinc has been able to handle UDP packets from a different
source address than those of the TCP packets since 1.0.10. When using multiple
BindToAddress statements, this code does not make sense anymore, we do want the
kernel to choose the source address on its own.
Tinc will now, by default, decrement the TTL field of incoming IPv4 and IPv6
packets, before forwarding them to the virtual network device or to another
node. Packets with a TTL value of zero will be dropped, and an ICMP Time
Exceeded message will be sent back.
This behaviour can be disabled using the DecrementTTL option.
Scripts called by tinc would inherit its open filedescriptors. This could
be a problem if other long-running daemons are started from those scripts,
if those daemons would not close all filedescriptors before going into the
background.
Problem found and solution suggested by Nick Hibma.
Apart from the platform specific tun/tap driver, link with the dummy and
raw_socket devices, and optionally with support for UML and VDE devices.
At runtime, the DeviceType option can be used to select which driver to
use.
* Exchange nonce and ECDH public key first, calculate the ECDSA signature
over the complete key exchange.
* Make an explicit distinction between client and server in the signatures.
* Add more comments and replace some magic numbers by #defines.
Thanks to Erik Tews for very helpful hints and comments!
In case the config file could not be opened a new but unitialized RSA structure
would be returned, causing a segmentation fault later on. This would only
happen in the case that the config file could be opened before, but not when
read_rsa_public_key() was called. This situation could occur when the --user
option was used, and the config files were not readable by the specified user.
Probably due to a merge, the try_harder() function had duplicated the
rate-limiting code for detecting the sender node based on the HMAC of the
packet. This prevented this detection from running at all. The function is now
identical again to that in the 1.0 branch.
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>
Encryption and authentication of the meta connection is spread out over
meta.c and protocol_auth.c. The new protocol was added there as well,
leading to spaghetti code. To improve things, the new protocol will now
be implemented in sptps.[ch].
The goal is to have a very simplified version of TLS. There is a record
layer, and there are only two record types: application data and
handshake messages. The handshake message contains a random nonce, an
ephemeral ECDH public key, and an ECDSA signature over the former. After
the ECDH public keys are exchanged, a shared secret is calculated, and a
TLS style PRF is used to generate the key material for the cipher and
HMAC algorithm, and further communication is encrypted and authenticated.
A lot of the simplicity comes from the fact that both sides must have
each other's public keys in advance, and there are no options to choose.
There will be one fixed cipher suite, and both peers always authenticate
each other. (Inspiration taken from Ian Grigg's hypotheses[0].)
There might be some compromise in the future, to enable or disable
encryption, authentication and compression, but there will be no choice
of algorithms. This will allow SPTPS to be built with a few embedded
crypto algorithms instead of linking with huge crypto libraries.
The API is also kept simple. There is a start and a stop function. All
data necessary to make the connection work is passed in the start
function. Instead having both send- and receive-record functions, there
is a send-record function and a receive-data function. The latter will
pass protocol data received from the peer to the SPTPS implementation,
which will in turn call a receive-record callback function when
necessary. This hides all the handshaking from the application, and is
completely independent from any event loop or socket characteristics.
[0] http://iang.org/ssl/hn_hypotheses_in_secure_protocol_design.html
This is mainly important for Windows, where the select() call in the
main thread is not being woken up when the tapreader thread calls
route(), causing a delay of up to 1 second before the output buffer is
flushed. This would cause bad performance when UDP communication is not
possible.
