Freies Vortragsprogramm (Fr, 05.05.2006)

A remote rescue environment for FreeBSD systems

von Adrian Steinmann (Webgroup Consulting AG)

Freitag, 05.05.2006, Saal 6.2, 10:00-11:00 Uhr

Unix systems traditionally do integrity checks and other initialization before bringing up network services. An error during those first few steps can cause the machine to hang in 'single user', awaiting input at the physical console.

It is shown how the standard 'crunchgen' utility is applied to build a small maintenance RAMdisk which supports Secure Shell as well as run-time loading for GEOM class commands like 'gmirror', 'graid3', and 'gstripe'.

This RAMdisk environment can be customized per machine via a configuration file which is read by the boot loader. As the system boots, one of the first operations is to configure networking and the Secure Shell daemon in a preloaded RAMdisk, even before the root filesystem is checked. A system administrator can then login to that environment and recover or upgrade the system.

This is particularly useful on small "embedded" systems where PXE booting is not possible or practical. This method has been developed and utilized for a number of years to remotely upgrade FreeBSD firewalls from one release to the next.

Über den Autor Adrian Steinmann:

Adrian Steinmann earned a PhD in Mathematical Physics from Swiss Federal Institute of Technology in Zürich, Switzerland. He has been working in the IT industry for over 20 years, mainly in transaction processing, networking, and Unix system administration. He is the founder of Webgroup Consulting AG and works on Open Source and IT Security with emphasis on FreeBSD and Perl. In his free time he likes to travel and sculpt. He lives in Zürich, Switzerland.