Posted by jfeedor | Posted in OpenSource | Posted on 16-08-2009
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I’ve been setting up some Ubuntu Jaunty systems for relatives as an excuse to get rid of a lot of old hardware including some SCSI scanners. I encountered an HP scanner that was supported by sane but not recognized by Ubuntu. The device ended up with the wrong permissions preventing anyone except root from scanning. This is an explanation of how to create a udev rule to automatically fix this type of problem.
Posted by jfeedor | Posted in OpenSource | Posted on 15-08-2009
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Many Linux distributions ship with the heartbeat suite of software for setting up High Availability Linux. The Linux HA project has details and downloads for those who do not have it available for their system. This text addresses setting up a very simple HA Linux configuration using the configuration files versus a GUI or the XML definition files. The example setup will have two servers that serve up an apache webserver. One can have many other services assigned as well and shared data over NFS for example. Similarly a common mysql db backend could be available or even more exotic tiered mysql dbs – basically whatever the needs are. What Linux HA can do is using a shared IP it can host the same IP from any server in the cluster list. For demonstration purposes, however, the apache servers root will have an index file with the actual hostname of the system – what should be observed is the index file contents will change after a failover but still be accessible via the shared IP.
Posted by jfeedor | Posted in OpenSource | Posted on 14-08-2009
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A Linux kernel bug in network socket initialization could allow an attacker to acquire root privileges to inflict damages. The security hole applies to all kernels of the 2.4 and 2.5 series and has been around possibly since 2001.
Posted by jfeedor | Posted in OpenSource | Posted on 18-07-2009
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Brad Spengler, the developer behind the Grsecurity project, has published an exploit for a vulnerability in the Tun interface in Linux kernel 2.6.30 and 2.6.18, used in Red Hat Enterprise Linux 5 (RHEL5), which can be exploited by attackers to obtain root privileges. Of particular interest is the fact that the exploit is even able to circumvent security extensions such as SELinux. According to Spengler’s report, the vulnerability is only found in these two versions of the kernel. The core of the problem is a normally non-exploitable null pointer dereference, which becomes exploitable due to the GCC’s optimisation function.