Setting Up Subversion for One or Multiple Projects
In the configuration section I mentioned the mod_authz_svn.so module, created and installed by the Subversion installation process. This module allows us to define the access control policy on a directory basis, thus increasing the level of granularity.
Why do we need a separate module to take care of directory-based access control? Couldn't we use Apache configuration primitives? The problem here is the URL passed to Apache to access a repository, which is of the form:
As we can see, only the project path and name is visible: the project's accessed directory is hidden in the numeric code. Thus, we cannot directly apply Apache Location-based access control primitives. The solution consists of delegating directory access control to the mod_authz_svn.so module, which is able to parse the numeric code and identify the accessed directory.
The mod_authz_svn.so's access control policy is specified in a plain-text file with a simple syntax. Here's the one we use for our public projects (/svn/conf/policies/public_svn_authz):
[groups] foo = john, bob bar = john, mike [/] * = r [foo:/] @foo = rw [foo:/branch/john] bob = r [foo:/branch/bob] john = r [bar:/] @bar = rw
We first define the groups of users we want to specify the policy for, then we list the access control rules. The one under the [/] section specifies that any user can read the content of any project. For each project (for example [foo:/]) we specify a global access control policy, specifying it for the inner directories. There's no need to specify an access control rule for user john in the /branch/john directory, because it's inherited from the one in the upper-level directory.
In addition, we had to specify again the different groups' composition. We should avoid replication of such configuration directives as a good security practice. This problem is solved simply by removing any AuthGroupFile directive from the project configuration files and changing the related Require directive to a Require valid-user one, thus delegating group management to the mod_authz_svn.so module.
At this point all that remains is to add the directive AuthzSVNAccessFile to the default policy files in order to tell Apache that we intend to use the mod_authz_svn.so module as an access control facility. To do so, we must specify its configuration file. Here's the one for public projects:
<Location /public> Dav svn SVNParentPath /tmp/LJ/svn/repository/public <LimitExcept GET PROPFIND OPTIONS REPORT> Order deny,allow Deny from all Allow from 127.0.0.1 Satisfy all </LimitExcept> AuthzSVNAccessFile /tmp/LJ/svn/conf/public_svn_authz </Location> <VirtualHost _default_:8081> <Location /public> Dav svn SVNParentPath /tmp/LJ/svn/repository/public Order allow,deny Allow from all <LimitExcept GET PROPFIND OPTIONS REPORT> Order deny,allow Deny from all Satisfy all </LimitExcept> AuthzSVNAccessFile /tmp/LJ/svn/conf/public_svn_authz </Location> Include /tmp/LJ/svn/conf/policies/public/* </VirtualHost>
You may ask why we didn't use the mod_authz_svn.so module before. If we hadn't any trusted subnets, we could throw away most of the Apache access control machinery and rely solely on the mod_authz_svn.so, even if this is true only from Subversion 1.0.1. But because mod_authz_svn.so's access control strategy is user-based when in the scenario with a trusted subnet, we need a mix of source-based access control and user-based access control.
Practical Task Scheduling Deployment
One of the best things about the UNIX environment (aside from being stable and efficient) is the vast array of software tools available to help you do your job. Traditionally, a UNIX tool does only one thing, but does that one thing very well. For example, grep is very easy to use and can search vast amounts of data quickly. The find tool can find a particular file or files based on all kinds of criteria. It's pretty easy to string these tools together to build even more powerful tools, such as a tool that finds all of the .log files in the /home directory and searches each one for a particular entry. This erector-set mentality allows UNIX system administrators to seem to always have the right tool for the job.
Cron traditionally has been considered another such a tool for job scheduling, but is it enough? This webinar considers that very question. The first part builds on a previous Geek Guide, Beyond Cron, and briefly describes how to know when it might be time to consider upgrading your job scheduling infrastructure. The second part presents an actual planning and implementation framework.
Join Linux Journal's Mike Diehl and Pat Cameron of Help Systems.
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|The Firebird Project's Firebird Relational Database||Jul 29, 2016|
|Stunnel Security for Oracle||Jul 28, 2016|
|SUSE LLC's SUSE Manager||Jul 21, 2016|
|My +1 Sword of Productivity||Jul 20, 2016|
|Non-Linux FOSS: Caffeine!||Jul 19, 2016|
|Murat Yener and Onur Dundar's Expert Android Studio (Wrox)||Jul 18, 2016|
- Stunnel Security for Oracle
- The Firebird Project's Firebird Relational Database
- SUSE LLC's SUSE Manager
- Murat Yener and Onur Dundar's Expert Android Studio (Wrox)
- Managing Linux Using Puppet
- My +1 Sword of Productivity
- Non-Linux FOSS: Caffeine!
- Google's SwiftShader Released
- SuperTuxKart 0.9.2 Released
- Doing for User Space What We Did for Kernel Space
With all the industry talk about the benefits of Linux on Power and all the performance advantages offered by its open architecture, you may be considering a move in that direction. If you are thinking about analytics, big data and cloud computing, you would be right to evaluate Power. The idea of using commodity x86 hardware and replacing it every three years is an outdated cost model. It doesn’t consider the total cost of ownership, and it doesn’t consider the advantage of real processing power, high-availability and multithreading like a demon.
This ebook takes a look at some of the practical applications of the Linux on Power platform and ways you might bring all the performance power of this open architecture to bear for your organization. There are no smoke and mirrors here—just hard, cold, empirical evidence provided by independent sources. I also consider some innovative ways Linux on Power will be used in the future.Get the Guide