1. Introduction
1.1 Who needs that
2. Principles
2.1 Non reversible isolation
2.2 Isolation areas
2.3 New system calls
2.4 Limiting super-user: The capabilities system
2.5 Enhancing the capability system
2.6 Playing with the new system calls
2.6.1 Playing with /usr/sbin/chcontext
2.6.2 Playing with /usr/sbin/chcontext as root
2.6.3 Playing with /usr/sbin/chbind
2.6.4 Playing with /usr/sbin/reducecap
2.7 Unification
3. Applications
3.1 Virtual server
3.2 Per user fire-wall
3.3 Secure server/Intrusion detection
3.4 Fail over servers
4. Installation
4.1 The packages
4.2 Setting a virtual server
4.3 Basic configuration of the virtual server
4.4 Entering the virtual server
4.5 Configuring the services
4.6 Starting/Stopping the virtual server
4.7 Starting/Stopping all the virtual servers
4.8 Restarting a virtual server from inside
4.9 Executing tasks at vserver start/stop time
4.10 Issues
4.11 How real is it ?
5. Features
6. Future directions
6.1 User controlled security box
6.2 Kernel enhancements
6.2.1 Per context disk quota
6.2.2 Global limits
6.2.3 Scheduler
6.2.4 Security issues
6.2.4.1 /dev/random
6.2.4.2 /dev/pts
6.2.4.3 Network devices
7. Alternative technologies
7.1 Virtual machines
7.2 Partitioning
7.3 Limitation of those technologies
8. Conclusion
9. Download
10. References
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4.6 Starting/Stopping the virtual server

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Virtual server with ONBOOT=yes will be started and stopped like any other services of the main server. But you can stop and start a virtual server at any time. Starting a server means that all configured service will be started. Stopping it means that all configured services will be stopped and then all remaining process will be killed.

Oddly, starting a virtual server does not mean much. There is no overhead. No monitoring process or proxy or emulator. Starting a virtual server with 4 services is the same as running those 4 services in the main server, at least performance wise (the service inside a virtual server are locked inside the security context).

The following commands may be used to control a virtual server:

  • /usr/sbin/vserver server start
  • /usr/sbin/vserver server stop
  • /usr/sbin/vserver server restart
  • /usr/sbin/vserver server running
  • /usr/sbin/vserver server enter
  • /usr/sbin/vserver server exec some commands ...
  • /usr/sbin/vserver server suexec user some commands ...
  • /usr/sbin/vserver server service service-name start/stop/restart/status
  • /usr/sbin/vserver server status

The running command prints if there are any processes running in the virtual server context.

Please note

The processes running in a virtual server are invisible from the main server. The opposite is true. This is very important. Managing the main server must not cause problems to the various virtual servers. For example, doing killall httpd will kill all the httpd processes in the current context ( the main server or a virtual one).

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