Product manual

NL200 Network Link Interface

7.4.4 TLS Proxy Server

A TLS proxy server is a device that acts as a secure intermediary for requests

from clients seeking resources from other servers. A client connects to the

proxy server, requesting some service, such as a file, connection, web page, or

other resource, available from a different server. The proxy server evaluates

the request according to its filtering rules. For example, it may filter traffic by

IP address or protocol. If the request is validated by the filter, the proxy

provides the resource by connecting to the relevant server and requesting the

service on behalf of the client.

The following NL200 settings apply to the implementation of a TLS Proxy

Server in the NL200. Set them from the Settings Editor | TLS Proxy Server tab

in DevConfig as required for your application:

TLS Proxy Server (enable/disable)

When the NL200 TLS Proxy Server is enabled, the NL200 TLS server

maintains a secure TLS connection with a remote TLS client and forwards

information to the datalogger using a standard unencrypted TCP connection.

TLS Proxy Server Port Number

In order to communicate with the NL200 TLS server, the client application

must open a socket to the NL200 TLS server. The socket of the NL200 TLS

server is uniquely identified by the IP address of the NL200 and a port number.

This entry defines the port number that the NL200 TLS Server is listening on.

If secure communications come in on this port, the NL200 will attempt to open

a TCP connection to the datalogger on the 'TLS Proxy Forward Port Number'

(default port is 6785).

Also, regardless of this setting, the NL200 TLS Proxy Server will always listen

on the secure HTTP (HTTPS) port number 443. If a secure connection is

established on this port the NL200 will attempt to communicate to the

datalogger on the HTTP port 80 (port number range is 1..65535).

TLS Proxy Forward Physical Port

If the 'TLS Proxy Forward Physical Port' is set to CS I/O port, the NL200 will

then open a TCP connection with the logger over the CS I/O port. Data

transfer between the NL200 and the datalogger is an unencrypted TCP

connection.

If the 'TLS Proxy Forward Physical Port' is set to Ethernet Port, then the

NL200 will open an unencrypted TCP connection over Ethernet to the defined

'TLS Proxy Forward IP Address.'

TLS Proxy Forward IP Address

This setting is used if Ethernet Port is selected under 'TLS Proxy Forward

Physical Port'. Secure communications received by the NL200 TLS Server

will be forwarded on a non-secure unencrypted TCP connection to this IP

address. A router may be used to create a private network to isolate the

unencrypted communications between the NL200 and the datalogger from the

unsecured network.