JPJ8;D@E X2Go J\im\i$YXj\[Zfdglk`e^n`k_k_\]i\\O)>fk\id`eXcj\im\i JK8P@E>K?@E The open source X2Go project is rapidly approaching version 3, which adds features such as new clients and seamless windows. BY HEINZ-M. GRAESING, MARKUS FEILNER JXe[iX:lee`e^_XdX#=fkfc`X 2Go [1] is a free, fast, and flexi- next user. If A then inserts his smartcard ble terminal server for any client into the reader on any other machine, leisure time developing a free terminal Othat supports modern authenti- the server immediately offers him the server that supported laptops and arbi- cation technologies, such as card read- interrupted session. trary clients, in contrast to Sun’s model. ers, USB tokens, centralized user man- Of course, Linux users were very Thanks to an intelligent combination of agement via LDAP, and authentication much interested in tools integrated in the KDE system man- a similar all-round agement system. system that, in The X2Go project was inspired by the contrast to Sun Sun Ray product line [2], which has im- Ray, did not rely pressed thin client fans since 2006. The on special hard- second Sun Ray release included lean ware, and it was devices that lets users log on using a just a question of smartcard to work on a centralized ter- time until the minal server [3] [4]. open source com- In addition to the multimedia extras munity delivered and security features integrated into the the goods. Sun Ray products, a session manage- Oleksandr Sh- ment system, dubbed “Hot Desktop neyder and Heinz Mobility” or “Hot Desking” by Sun, was Gräsing, system probably the sexiest feature. administrators When user A removes his chip card with the City of from the internal card reader, the soft- Treuchtlingen, =`^li\(1O)>flj\ijZXecf^fen`k_XjdXikZXi[#LJ9jk`Zb#fi ware automatically interrupts the ses- Germany, spent gXjjnfi[%K_\[\m\cfg\ijZi\Xk\[ZXi[jn`k_dXkZ_`e^`dX^\j]ifd sion, freeing up the thin client for the much of their k_\B;<lj\idXeX^\i]fik_\[\dfm\ij`fe% 66 ISSUE 98 JANUARY 2009 066-069_x2go.indd 66 13.11.2008 15:46:02 Uhr X2Go JPJ8;D@E =`^li\)1N_\ecf^^`e^fen`k_k_\O)>fZc`\ek#k_\lj\iZXe j\c\Zkn_\k_\ikfcXleZ_XC`elo[\jbkfg#jlZ_XjB;<fi>efd\# =`^li\+1K_\i\Z\ekcpi\c\Xj\[>kbZc`\ekcffbjm\ipj`d`cXikfk_\Hk fialjkcXleZ_Xggc`ZXk`fej\dY\[[\[`ek_\cfZXc\em`ifed\ek% m\ij`feYlkn`ccilefe>efd\% GPL’d software and their own develop- nux4Paraguay in Paraguay, as well as in vice for individual X2Go modules that ments, the team came up with a con- many German schools (see the “Linux4- will allow users to access files, sound, vincing answer: X2Go. Afrika and X2Go” box). applications, or the complete desktop of a Linux machine over the Internet. @ek\^iXk\[Kffcj 9iXe[E\n1M\ij`fe* As the X2Go developers revealed at The developers integrated tools such as Version 3 will probably be available for Ubuconf, they envisage a kind of private PXE boot and Debootstrap [5], NoMa- production use by the time this issue hits cloud computing dubbed Pccloud some chine’s free NX libraries [6][7], and tools the newsstands. The project is Debian time in the future; the cloud would use like FUSE [8] and SSHFS [9] with desk- oriented, so the X2Go developers are profile data to synchronize the session top utilities and extensions for Gnome waiting for the stable version of Lenny with the individual environment, includ- and KDE. PAM libraries add smartcard before they go stable. ing applications and data from online support and USB stick-based authentica- Four new features on the list outshine storage. tion to X2Go (Figure 1). the numerous bug fixes and detail im- An X2Go USB stick is also planned as Thanks to the NX server’s ability to provements: Besides Windows, Mac OS a portable Windows application. suspend and resume sessions, version 2 X, and Linux, they now have a mobile X2Go seeks to create an open – but was the first to support Sun Ray-style client for the open source Maemo [11] complete – terminal server environment, sign-on. platform for Nokia phones and the long- which explains the many software addi- anticipated Gtk client, including Gnome tions to the distribution. Additions in- Nfic[KiXm\c\i integration. The fourth addition is the clude mechanisms for distributing the X2Go is now deployed on the clients and ability for users to run individual appli- client filesystem via PXE boot, a login servers developed for Linux4Afrika [10] cations without a desktop (Figure 2), manager, administrative plugins for the in Tanzania and Mozambique and Li- just as on Citrix. KDE control center, and tools. NX com- Although the Qt client pression methods allow for sessions over supports all the new low-bandwidth links. functions, the develop- ers are still smoothing :fdgc\k\cpFg\eJfliZ\ off some rough edges. X2Go is not compatible with LTSP or For example, the newly NX, but goes its own way. The project implemented USB au- wants to avoid the need to integrate ap- thentication is not quite plications for file or media shares in the finished. If you need server and client; thus, it relies on solu- this, you might want to tions such as FUSE and SSHFS, which wait until the developers are both maintained by other parties. All have completed security the components are open source, and features like time- the full source code is available for stamps, client IDs, and download from the project’s homepage. changing tokens before The three X2Go clients differ only =`^li\*1O)>fi\Z\ekcpi\c\Xj\[Xk\id`eXcZc`\ek]fik_\ you update. slightly with respect to functionality, al- DX\dfgcXk]fidlj\[Ypk_\Efb`XE..'&/''Xe[E/(' The next item on the though they rely on different libraries. jdXikg_fe\j% to-do list is a web ser- The Qt 4 client in Figure 3 runs on JANUARY 2009 ISSUE 98 67 066-069_x2go.indd 67 13.11.2008 15:46:04 Uhr JPJ8;D@E X2Go Linux, Windows, Mac OS SSHFS for file trans- (or better) that supports OpenPGP card X, and Maemo, and – just fers, relying on the [12]. like its new Gtk counterpart packages maintained (Figure 4) – either as a full- by the distribution O)>fJ\im\i screen display manager in for this. A range of variants of the X2Go server the style of XDM or as a =`^li\,1@]k_\lj\i`jefkX X2Go uses Udev to component are available; the basic ver- standalone application. In d\dY\if]k_\O)>f^iflg# support local mass sion takes less than 10 minutes to install both cases, administrators k_\Zc`\ekn`cc`jjl\Xd\jjX^\ storage devices, such and is perfectly okay for test purposes either can allow individual ZfeZ\ie`e^k_\`eZfii\Zk Zfe$ as CD-ROMs, and au- and for most private desktops. It in- configurations or tell X2Go ]`^liXk`fef]k_\jl[fjpjk\d% tomatically connects cludes secure remote access, shares, and to use a central LDAP them to the server. sound output and does not rely on an server. For computers that do not have a hard- LDAP installation [13][14]. All graphical clients follow the same ware key to eject media, the desktop Admins prepared to invest more time usability concept (see Figures 2--4). The displays an icon that forwards the com- in installing X2Go will be rewarded with widget set used here was dubbed Card- mands to the client; this feature is im- multiserver capabilities and central man- view and uses a business card-style ap- portant for Mac clients. agement for settings, users, and groups proach. While a session is running, users can via LDAP using Luma [15], for example. Sessions, users, and configurations are share additional directories (Figure 5). If you need to support thin clients that configurable via drop-down lists and X2Go automatically adds them to the use PXE to boot individual images, there pop-ups in this view, without the need desktop like statically configured filesys- is no alternative to setting up a directory to switch to an admin tool. However, if tem shares and adds entries for un- service. X2Go does not require individ- an LDAP server is used to manage user mounting to the drop-down menu. ual schemas but will integrate with exist- and configuration data, a client-side con- Besides simple username and pass- ing configurations. Centralized manage- figuration is not needed; the tool simply word-based logins, X2Go also supports ment of active sessions is supported by a shows a list of users allowed to log on Sun-style flexible sessions to go, includ- PostgreSQL database; a central instance from the current system. ing smartcard or USB stick-based au- is sufficient for multiple X2Go servers on thentication. However, there is no alter- a network. N`e[fnjXe[:C@ native to a crypto filesystem on the USB Sudo helps admins specify which user The X2Go client can be configured via a stick; otherwise, users that gain access groups are permitted to log on to the simple desktop program that is reminis- to a lost stick could simply read the ID X2Go service. Because during the instal- cent of a physical terminal server client. number. lation phase the visudo-based configura- Again access to a central LDAP directory Admins in professional environments tion is difficult for newcomers, the new is possible, and on top of this, users can will probably want to opt for the security client version now checks to see whether access other servers and resize and hide of a smartcard instead, the advantage the user is a member of the required the window during use.