VDE_CRYPTCAB(1)VDE_CRYPTCAB(1)NAMEvde_cryptcab - Virtual Distributed Ethernet encrypted cable manager
SYNOPSISvde_cryptcab [ -p portnum ] [ -s socketpath ] [ -c
[remote_user@]host[:remote_portnum] ] [ -P pre_shared.key ]| [ -x ] [
-v [v][v][v] ] [ -k ] [ -d ]
DESCRIPTION
A vde_cryptcab is a distributed cable manager for VDE switches. It
allows two VDE switches on two machines to communicate using a blowfish
encrypted channel.
When used in client mode (i.e., with -c option), it generates a random
blowfish key, and uses scp (1) to transfer the key to the remote
server.
On the client side, the environment variable SCP_EXTRA_OPTIONS may be
set in order to append options to the scp command line (this is useful
for example when dropbear or another non-standard ssh client is used to
transfer the blowfish key).
After a 4-way handshake phase to verify client credentials, server and
client will exchange VDE datagrams encapsulating them into cryptograms
that are sent via udp to each remote host.
On server side, one could run:
vde_cryptcab-s /tmp/vde2.ctl -p 2100
To start a multi-peer cryptcab server, accepting udp datagrams on port
2100, that connects each authenticated remote client to a different
port of the switch. In fact, a new instance of vde_plug (1) is started
and connected to the switch through local unix socket.
The command
vde_cryptcab-s /tmp/vde2.ctl -c foo@remote.machine.org:2100
will connect a client to the remote server, running on udp port 2100.
At this point, on server side a verify for user "foo" credentials is
required, typically it could be: host-based authentication, password
challenge or public key authentication. See ssh (1) for more details
about it.
If the two vde_switches run as daemon and they are connected to tap
interfaces a level 2 encrypted tunnel is established.
OPTIONS-p portnum
It is possible to decide which local udp port to use. When this
option is not specified, cryptcab will use default udp port num‐
ber, 7667.
-c [remote_user@]host[:remote_portnum]
run vde_cryptcab in client mode, trying to connect to host .
Both remote_user and remote_portnum parameters are not required.
If not specified, the same user running vde_cryptcab is used for
authentication on server, and default udp port 7667 is used.
-s socketpath
specify the UNIX socket to be used by local programs for joining
the VDE. The default value is "/tmp/vde.ctl".
-P pre_shared.keypath
if specified, vde_cryptcab will run in pre-shared key mode,
instead of generating a random key to transmit with ssh. Given
option is the path to the pre-shared symmetric key file to use
for data encryption. The same key has to be used on both client
and server.
-x Disable symmetric key encryption.
-k Send periodic "keepalive" packets to avoid server timeouts. Use‐
ful when you want to keep a low-traffic link available.
-d Run as daemon.
-v Verbose. (Use -vv -vvv or -vvvv for more verbosity)
KNOWN ISSUES
Encapsulating IP packets into session+udp layer results in real data‐
grams larger than tap device mtu. Since vde_cryptcab gets confused by
packet fragmentation, the tap device mtu must be set to a smaller value
than real interface mtu. Use ip(8) or ifconfig(8) to set up your tap
device mtu.
Explicitly disabling encryption leads to obvious security problems. It
is advised to avoid unencrypted mode (-x) in non-controlled networks.
NOTICE
Virtual Distributed Ethernet is not related in any way with www.vde.com
("Verband der Elektrotechnik, Elektronik und Informationstechnik" i.e.
the German "Association for Electrical, Electronic & Information Tech‐
nologies").
SEE ALSOvde_switch(1), vdeq(1), vde_plug(1), vde_plug2tap(1), scp(1), ssh(1).
AUTHORS
VDE is a project by Renzo Davoli <renzo@cs.unibo.it>.
vde_cryptcab is a VDE component by Daniele Lacamera
<root@danielinux.net>
Virtual Distributed Ethernet December 6, 2006 VDE_CRYPTCAB(1)
