Technical Spec´s XOT Software LINUX *

© Farsite Communication Ltd. • 2012


FarSync XOT Runtime has been developed to provide high performance and very reliable XOT connectivity for Linux. FarSync XOT Runtime for Linux inter-operates with the FarLinX X25 Gateway , FarSync XOT Runtime for Windows and other third party XOT devices, which can allow a complete X.25 network to be replaced by TCP/IP including IPv6, eliminating hardware and costs just leaving a short X.25 connection to the host. The diagram above illustrates this.

There are 2 main APIs, a Sockets based interface and a Java API. There is also an APIs to the ISO Transport layers (ISO 8073 - connection oriented). A comprehensive Developers Toolkit is included with the product. The API is compatible with the FarSync X.25 APIs.

FarSync XOT Runtime is supported on Linux kernel versions 2.6 and 3.0, including the leading distributions supplied by Redhat, SuSE, Mandriva, Debian, Ubuntu, Slackware, Fedora and others. Multi-processor, 32 and 64 bit systems are supported. FarSite is committed to supporting the FarSync XOT products on new versions of Linux as they are released. The source code for the driver and the libraries for the API are supplied with the product.

New Features with version 3.1

        • Support for up to 4,095 simultaneous sessions, previously the maximum was 1,000
        • The TCP/IP handling now includes support for IPv6 addressing
        • TCP/IP keepalives now enabled by default and can be selected or deselected for each connection definition. Use of keepalives improves the response of the XOT to TCP/IP network problems, providing the Applications with earlier notification of network failures
        • The non standard XOT keepalives used by some XOT implementations are also supported
        • Supports version 3.0 kernels and the more recent Linux distributions by Redhat, SuSE, Debian, Ubuntu, Slackware and Fedora
        • Improved session establishment speed and data throughput performance

Typical Applications

        • The FarSync XOT Runtime is suitable for connection to remote systems running XOT, typical applications include:
        • XOT replacements for X.25 networksE-Commerce gateways for credit verification
        • E-Commerce gateways for credit verification

Developers Toolkit

The Developers Toolkit is included free with the FarSync XOT Runtime product and features:

        • Documented working C and Java source sample programs. Source code from these samples can be used to fast-track your development process.
        • Comprehensive API manuals with function call definitions and helpful advice on the best way to utilise the various interfaces.
        • Source code for the drivers and API libraries.
        • Line monitoring analyser for the X.25/XOT traffic
        • Free email and telephone assistance to application developers.

APIs for Application Development

For application developers needing to access XOT there is a choice of a Sockets API or a Java API. Both APIs interfaces may be used simultaneously by different programs if required. API manuals and many example applications are included in the Developers Toolkit for both types of interface. The APIs are compatible with the APIs for FarSync X.25 cards.

Sockets API

The Sockets interface provides a programming language independent high level connection orientated interface with access to a comprehensive set of X.25 features. The FarSync Sockets implementation is compatible with the BSD Sockets interface. The API is compatible with the Sockets API for the FarSync X25 cards. Multi-threaded applications are supported.

Java API

The Java API allows applications written in Core Java Software (J2SE) and Enterprise Java Software (J2EE) easy access to the functions and features of FarSync XOT. Full documentation and sample applications are provided.

ISO Transport API

The interface provides a programming language independent, connection orientated interface controlled by command blocks. Full access is available to ISO Transport (ISO 8073 - connection orientated) Classes 0 to 3.


Configuration is by a Java and XML-based GUI configuration applicationText file based configuration is also available if required.


Installation scripts adapt to install the software on the major Linux distributions and a manual install option is available using the scripts as a guide, available on the CD-ROM. Source code is available as a .tar.gz.
A comprehensive configuration guide, commands reference and configuration examples are provided as part of the HTML documentation pack.


A line monitor utility is included, this can display data sent over the XOT lines at the frame and packet level, it is invaluable when developing and debugging applications. A status utility allows display of the channel connection status and statistics of user data, packet and frame types.


The XOT software, utilities and the Developers Toolkit are all included on the CD-ROM.

Technical Specifications

Operation Systems supported

Linux distributions supplied by Redhat, SuSE, Mandriva, Debian,   Ubuntu, Slackware, Fedora and others. FarSite is committed to supporting the FarSync XOT Runtime on new versions of Linux as they are released.

Linux Kernel Support

All sub versions of kernel releases from 2.6.9 onward and 3.0. The product may operate successfully with earlier versions of the kernel but no specific testing has been undertaken.

Multi-processor systems

The software has been designed for and tested on single and multiprocessor servers

64 bit systems

Designed for and tested on single and multi-processor) Servers, 32 and 64 bit systems.


IPv4 and IPv6

XOT Features

XOT Specification

Complies with RFC 1613 - X.25 over TCP (XOT)

Maximum XOT connections


Maximum SVCs and PVCs

4,095, any mix of SVCs and PVCs

Data Throughput

up to 50 Mbits/s

Data packets size range

0 to 4,096 bytes

OOB (Out of Band) data

Supported for Interrupts, Resets and the D bit

X25 facilities supported

Closed User Group (CUG), Network User Identifier (NUI), Fast Select, Packet and Windows size negotiation, Throughput Class Negotiation.

Accessible via API

Two APIs, a Sockets based interface and a Java API.

ISO Transport Features

Standard supported

ISO 8073 (connection oriented)

Classes supported

Classes 0, 1, 2 and 3

Negotiation between classes


Simultaneous transport connections

Up to 4,095

Accessible via API


Developers Toolkit


Sockets API, easy to use, provides access to XOT features, recommended for new developments. 
Java API, allows easy access to XOT from Java applications.

ISO Transport API

NCB based API providing access to all the features of the ISO Transport support. Can operate simultaneously   with access to the XOT layer.

API reference manuals

Manuals: XOT (and X.25) Sockets API, ISO Transport API and Java API documentation.

Sample programs

Included, large number of example applications are available for driving the various APIs.

Source code

Included for drivers, the API libraries and sample C and Java applications.

* All specifications are subject to change