Conc - A serial terminal concentrator for Gnome

Conc is a console concentrator for Linux and Gnome. It features remote maintenance of systems over IP, and concurrent connections to consoles. Serial lines on multiple machines may be pooled into one system allowing a virtually unlimited number of consoles to be managed - ideal for large server farms, clusters or off-site server rooms.

Please feel free to try it out and send me any comments, feature requests, and bug reports.



Conc-2.0.3 is released.

This release fixes some minor bugs and adds a few new features, including support IPMI serial-over-LAN and SSL for client connections.


Conc-2.0.2 is released.

Wow - it's a long time since the last update! This release fixes a couple of quite serious bugs, including a buffer overflow.


Conc-2.0.1 is released.

This release improves the reliability of the connection between manager and servers, and removes the worst of the memory leaks from the client.


Conc-2.0.0 is released.

This release fixes compile problems with GNOME 2.14 and later. There are still some issues with the client leaking memory, but it is very usable so it is now the official stable version. I need to update the rest of this web page to reflect the new system and hopefully I will find time to do this in the not too distant future.


Conc-1.9.4 is released.

This release fixes a few minor bugs and has been used in a production environment for some months without issue, so I'm going to call it the beta release. If all goes well, the next version of Conc will be 2.0.0.


Conc-1.9.3 is released.

This release fixes some manager bugs that could cause the system to hang if a server were not available. The user interface has also been improved, with most lists now being sorted alphabetically.


Conc-1.9.2 is released.

This release could be considered an alpha release. I plan to use this version in anger at work to iron out any remaining bugs. There is some initial, incomplete documentation.


Having utterly failed to comply with the "release often" part of the OSS mantra, I offer this to satisfy the "release early" part. Conc-1.9.1 is not yet ready for prime-time use; in particular there is absolutely no documentation supplied currently. However, it does represent the first step on the way to Conc-2.X, and I wanted to release as much as anything to indicate that Conc is being actively worked on.


Conc-1.1 is released.

This release fixes a minor bug that can affect starting of remote termservs. The system can now be configured to use ssh instead of rsh. No more features to be added to 1.X, a 2.X development tree is about to be opened.


Conc-1.0 is released.

This release marks the first stable version. A few minor bugs were fixed.


Documentation is now available online.

Conc-0.6 is released.

This should be the final release before the 1.0 stable release. Now is a very good time to report that bug that's irritating you!


Conc-0.5 is released.

I am considering this release of the software as a beta release. It is now being used on a day-to-day basis at my place of work, and I need a stable version to run there. There are still a few bugs, but they are mostly user interface glitches that do not affect overall operation of the system. I hope to squash as many of these bugs and possible and finish the documentation before making a conc-1.0 stable release. At that point I will open a development tree and attack some of the things in the TODO list.


An overview of conc.

This overview describes version 1 of conc. Please refer to the documentation packaged with version 2 for an overview of that system. They are broadly similar, however.

The systems consists of three components. The first is concserv, the central daemon, that keeps logs from all the consoles and coordinates the rest of the system. When it starts, concserv spawns a number of termserv processes that control the serial lines to which the console lines are connected. The link between a termserv and concserv is encrypted and termservs may run on separate machines to concserv, communicated over TCP/IP.

The final component, conc, is the user interface. It connects to concserv over an encrypted TCP/IP link, and allows the system administrator to view the logs of a particular machine, connect to its console, add and remove consoles etc. There is also a small, text-based interface called console that allows connection to a single console.

Any number of user interface programs may run concurrently and multiple connections to the same are possible, allowing groups to work on one system. Having all the components communicate by TCP/IP allows administration of machines from off site or unifying management of co-located and local equipment.


The official stable release is available at There is also a screenshot, and ChangeLog available.

Old Releases


Warning: this section is currently out of date. Please refer to the system's online help.

The manual for the latest stable version is available.

Serial Ports

A solution for rack mounting a Comtrol Rocketport.

The most expensive part of building a Linux based console concentrator is the hardware to provide a suitable number of serial ports. We use Comtrol's Rockport card - a reliable, if expensive, 16 channel serial card with excellent Linux support.