NAME

DESCRIPTION

File consists of sections in the form:

name {
  keyword value;
  keyword value;
  ..
}
    

Semicolon at the end of each keyword-value pair is required, as well as grouping curly braces {}. Lines which begin with '#' characters are comments.

Name of section (name) can be one of:

options

this section specifies general options for vtund

default

specifies default options for all sessions

session

(any other word except "options" and "default") introduces new session and specifies options for it.

All keyword names can be abbreviated to a minimum of 4 characters.

GENERAL OPTIONS

type stand|inetd

server type. vtund(8) can operate in standalone mode (stand), that is the default (but not available on no-MMU systems), or be invoked from inetd(8).

port portnumber

server port number to listen on or connect to. By default, vtund(8) uses port 5000.

bindaddr list

server listen address. Used to force vtund to bind to the specific address and port in server mode. Format:

  bindaddr {
   option value;
  };
    

bindaddr options:

timeout seconds

General timeout.

persist yes|keep|no

persist mode. If yes, the client will try to reconnect to the server after connection termination. If keep, the client will not remove and re-add the tunXX or tapXX device when reconnecting. If no, the client will exit (default). This option is ignored by the server.

syslog number|name

syslog facility specification, either numeric or name (from syslog (3)).

ppp path

path to pppd(8) program. Can be used in session sections.

ifconfig path

path to ifconfig(8) program. Can be used in session sections.

route path

path to route(8) program. Can be used in session sections.

ip path

path to iproute(8) program. Can be used in session sections.

firewall path

program for the firewall setup.

All the ppp, ifconfig, route and firewall parameters can specify a filename for corresponding program or equivalent (or shell script). This parameters are used in session sections to setup network interfaces.

SESSION OPTIONS

passwd secret

password for authentication. This should be the same in client and server.

type type

type of tunnel. Possible tunnel types are:

Default tunnel type is tty. This option is ignored by client.

device dev

network device to use. You can choose tapXX for ether tunnel or tunXX for tun tunnel. By default vtund(8) will automatically select available device.

proto tcp|udp

protocol to use. By default, vtund(8) will use TCP protocol. UDP is recommended for ether and tun tunnels only. This option is ignored by the client.

nat_hack client|server|no

side to use nat_hack on. By default, vtund(8) uses a 'no' setting. The side that the NAT hack is enabled on will perform a delayed UDP socket connect. Should only be enabled for the side outside of the NAT (typically the server)! Setting 'client' on the server or 'server' on the client is ignored, as to make a single configuration file reusable on both sides.

This is only relevant if you use proto udp. The NAT hack delays the UDP socket connect until the first UDP packet is received from the other side of the tunnel. The socket is then connected to the actual source port of the packet (on the NAT box) and not to the one indicated in the handshake (which is behind NAT and probably unreachable). The first echo request is also disabled on the side with the NAT hack enabled.

Currently the mechanism works only for one side, for a single NAT traversal. If you enable it for both sides, both will wait for a first packet and the tunnel will never transport any data.

Security warning! Due to the nature of the delayed connection, the tunnel can be hijacked in theory by an attacker behind the same NAT, sending the first UDP packet to the server UDP port, before the real client does. If you do not understand the risks, or want to remain as secure as possible behind this kind of NAT router, use proto tcp as a NAT traversal solution.

Because of the security issue mentioned above, this option might be disabled during compilation (configure --disable-nathack).

timeout secounds

Connect timeout.

compress method[:level]

specifies compression method to use. Compression methods include:

You can also specify level of compression using one digit (1 is best speed, 9 is best compression ratio). This option is ignored by the client.

encrypt method[:level]

specifies encryption method to use. Encryption methods include:

This option is ignored by the client.

keepalive yes|no|interval:count

enable or disable connection keep-alive. Time interval is a period between connection checks, in seconds, and count is the maximum number of retries (yes = 30:4). This option is ignored by the server.

stat yes|no

enable or disable statistics. If enabled vtund(8) will log statistic counters to /var/log/vtund/session_X every 5 minutes.

speed kbps

specifies speed of the connection in kilobits/second. Valid values for kbps are 8,16,32,64,128,256,etc. 0 (the default) means maximum possible speed without shaping. You can specify speed in form in:out, where in is speed to client, out - from the client. Single number means the same speed for in and out. This option ignored by the client.

srcaddr list

local (source) address. Used to force vtund to bind to the specific address and port. Format:

  srcaddr {
   option value;
   option value;
   ..
  };
    

srcaddr options:

multi value

control multiple connections. value can be yes or allow to allow multiple connections, no or deny to deny them or killold to allow new connection and kill old one. Ignored by the client.

up list

list of programs to run after connection has been established. Used to initialize protocols, devices, routing and firewall. This option looks like whole section inside of session section. For now, it's impossible to run up commands on no-MMU systems, so the section is ignored there. Format:

 up {
   option value;
   option value;
   ..
 };
    

Options inside up (and down) blocks:

down list

list of programs to run after connection has been terminated. It is similar to up parameter above. Not available on no-MMU systems too. Format:

 down {
   option value;
   option value;
   ..
 };
    

NOTES

SEE ALSO

AUTHOR