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Linux Screen Shortcuts

August 18, 2011 mohancheema 0

Screen is a much under utilised program, which provides the following functionality:

  • Remote terminal session management (detaching or sharing terminal sessions)
  • unlimited windows (unlike the hard-coded number of Linux virtual consoles)
  • Scroll back buffer (not limited to video memory like Linux virtual consoles)
  • copy/paste between windows

How to disable directory listing in APACHE

October 11, 2010 mohancheema 1

One of the “must do’s” on setting a secure apache webserver environment is to disable directory listing. As a default Apache will be compiled with this option enabled, but its always a good idea to get rid of this setting unless its really necessary.

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Apache connections dropped by Haproxy

October 6, 2010 mohancheema 0

Many times on RHEL, haproxy is not reliable it gives an errors while connecting to apache backend, at that time it logs the following errors into /var/log/messages

kernel: ip_conntrack: table full, dropping packet

this is related to ip_conntrack kernel module.

If found this error message into /var/log/messages need to apply following steps

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ip_conntrack_max table full dropping packets

September 28, 2010 mohancheema 0

If you notice the above message in syslog, it looks like the conntrack database doesn’t have enough entries for your environment. Connection tracking by default handles up to a certain number of simultaneous connections. This number is dependent on you system’s maximum memory size.

Some symptoms can be: