Some times I’ll run into an Ubuntu install where “vi” does not work as expected. For example the backspace and arrow keys will in insert mode will add characters. Turns out Ubuntu installs vim-tiny by default which is a stripped down (and historically compatible) version of vi. The solution is just to install the full version:
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sudo apt-get install vim |
This post post gives a very effective way to cause TCP connections to be more rapidly recycled: http://ihazem.wordpress.com/2012/02/07/reducing-time_wait-socket-connections-recyclereuse/
AIDE or Advanced Intrusion Detection Environment is a great tool for host based system integrity monitoring. AIDE will maintain a database of checksums on the content and attributes of critical system files. If these files change then a notification email will be sent. Here’s the homepage for the AIDE project: http://aide.sourceforge.net/ Installing AIDE is easy since it’s available via yum:
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yum install aide |
Edit the configuration file at /etc/aide.conf and make the following changes: Change “verbose” from 5 to 0. Change rule for “/var/log/lastlog” from “LSPP” to “LOG” To setup just do:
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/usr/sbin/aide --init cp /var/lib/aide/aide.db.new.gz /var/lib/aide/aide.db.gz |
Also add a daily cronjob that runs a check operation:
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0 5 * * * /usr/sbin/aide --check |
This job will send notification email to “root”. Make sure “root” is aliased to an appropriate address so the notifications will actually be received. The procedure when you receive a notification should be to: Review the changed files and confirm that the changes are legitimate. Update the aide
Interesting discussion here: http://stackoverflow.com/questions/410616/increasing-the-maximum-number-of-tcp-ip-connections-in-linux Especially, this section: Default Sysctl values on a typical linux box for tcp_tw_recycle & tcp_tw_reuse would be
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net.ipv4.tcp_tw_recycle = 0 net.ipv4.tcp_tw_reuse = 0 |
These do not allow a connection in wait state after use, and force them to last the complete time_wait cycle. I recommend setting them to:
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net.ipv4.tcp_tw_recycle = 1 net.ipv4.tcp_tw_reuse = 1 |
This allows fast cycling of sockets in time_wait state and re-using them. But before you do this change make sure that this does not conflict with the protocols that you would use for the application that needs these sockets. Some other references: http://www.speedguide.net/articles/linux-tweaking-121 and http://wiki.docdroppers.org/index.php?title=Sysctl_Modifications
Configuration for enable modules is stored in: /etc/apache2/mods-enabled Available but inactive modules are stored in: /etc/apache2/mods-available A module can be enabled with:
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a2enmod [modulename] |
Where [modulename] is the module to be enabled. For example:
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a2enmod rewrite |
will enable the rewrite module. A module can be disabled in a similar fashion with:
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a2dismod [modulename] |
Don’t forget to restart apache after making changes with:
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service apache2 restart |
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