OS4X Proxy

OS4X Proxy is the solution to connect your internal OFTP station to the external internet.

Due to the fact that internet is often not accessible from internal stations AND internal stations are normally not available from external internet, OS4X Proxy offers a secure solution to interact with the global internet without offering direct access of the OFTP station to the offending internet.

Involved programs

The OS4X Proxy consists of two parts:

• OS4X Proxy: the program communicating to the external internet
• OS4X Proxyclient: the program communicating to the internal network

The external communication is completely free in configuration on which port and device it listens. The internal proxy client is capable to forward incoming calls to a given internal service reachable via TCP/IP. This may be on the local host or even on another different station.

Common situations

Some situations are common sense of security and offer a wide range of network implementations.

Expose a single port to the internet

In order to listen on a specified port on a single IP address in the DMZ (de-militarized zone), the OS4X proxy can be installed in this instance in order to forward OFTP data to an internally connected proxy client.

Forward internal OFTP data to the external internet

When connecting to the outside world over a single point of connectivity, the OS4X Proxy constellation will solve this situation.

Licensing

OS4X Proxy is licensed via a license file at the OS4X Proxy (not client) side: only one license is needed to keep the system up and running. This license is based on an OS4X Proxy ID on the proxy server side, which can be easily obtained via a command line parameter:

dmz:~ # /opt/os4x/os4x_proxy -L
OS4X Proxy ID: c6bc8d9b37c5e36333a41acdda653aaef7fd4a00459eeb32a8a41059e23017c8px

This OS4X Proxy ID is needed for license generation, which can be done for test purposes on the product website at http://www.os4x.com/key.

The valid license will be searched by default at

/etc/os4x_proxy.lic

but an alternative location can be given with the commandline option "-l":

dmz:~ # /opt/os4x/os4x_proxy -l /usr/licenses/os4x_proxy.lic

OS4X Proxy

All external communication is done via the OS4X Proxy. This daemon runs normally in the background without any interaction. It's optimized on size and speed. No logical operations are implemented here, so no OFTP operations are located in this securely separated location.

Behaviour

The OS4X Proxy searches for a valid license for startup. This is searched at the location given with the parameter "-l" or at the default location "/etc/os4x_proxy.lic". If something is wrong with the license, the actual OS4X Proxy ID will be printed out with a message that the license file (with location) is invalid. Example:

dmz:~ # /opt/os4x/os4x_proxy -l /tmp/invalid.lic
ERROR: invalid license found in '/tmp/invalid.lic'! Please obtain a valid OS4X Proxy license for your OS4X Proxy ID:
  c6bc8d9b37c5e36333a41acdda653aaef7fd4a00459eeb32a8a41059e23017c8px

After successful startup, the OS4X Proxy listens on the port for internal communication only. No external availability is given at this point of time! After a OS4X Proxyclient connects to the OS4X Proxy, the OS4X Proxy will open the configured external port on the configured IP listening for incoming connections.

Every single incoming connection will be signalized to the connected OS4X Proxyclient, which will then open a new connection to the OS4X Proxy over the used TCP/IP port for handling this incoming connection. Additionally, the OS4X Proxyclient will establish a connection to the configured internal network target. If this connection fails, the external connection will instantly be closed.

Every single new incoming internal connection on the OS4X Proxy side will handle the internal protocol for outgoing connections. This is used for establishing outgoing connections initiated from the internal network connected over the OS4X Proxyclient. If one of both ends closes the connection, the corresponding other side will be actively informed about this situation which will then close the other end connection.

Commandline options

OS4X Proxy daemon build 20110412

usage:
-h: this help text
-v: display version
-i [<IP of device>]:<port>: accept from (optional) device on given port for internal connections.
                            defaults: IP of device: 0.0.0.0 (any)
                            --------- port: 65432
-e [<IP of device>]:<port>: accept from (optional) device on given port for external connections.
                            defaults: IP of device: 0.0.0.0 (any)
                            --------- port: 6619
[-T <seconds>: TCP/IP timeout (default: 180 seconds)]
-d: enable debug mode (don't daemonize)
-t: enable trace mode (don't daemonize, extreme logging)

License options:
-L: print out OS4X Proxy ID (basis for license)
-l <license file>: point to readable license file (default: /etc/os4x_proxy.lic)

OS4X Proxyclient

The OS4X Proxyclient communicates with the OS4X Proxy via a single given TCP/IP port. All internal OFTP communication traffic is routed over this internal daemon.

Commandline options

OS4X Proxy client build 20110411

usage:
-h: this help text
-v: display version
[-Q <portnumber>: internal port number to listen for internal connections for outgoing connections (default: 65433)]
-i [<IP of OS4X receive daemon>]:<port>: forward packages to internal OS4X receive daemon.
                            defaults: localhost
                            --------- port: 6619
-e [<IP of proxy>]:<port>: connect to given OS4X proxy server.
                            defaults: IP of device: none - to be set
                            --------- port: 65432
[-T <seconds>: TCP/IP timeout (default: 180 seconds)]
-d: enable debug mode (don't daemonize)
-t: enable trace mode (don't daemonize, extreme logging)