Daily *Nix

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====== Daily Admin Issue ======

   * [[ sar reporting ]]
   * [[ Kernel Tuning ]]
   * [[ inotify monitor ]]
   * [[ Security ]]

==== Centos 6 to 7 Upgrade ====

I've followed [[https://wiki.centos.org/TipsAndTricks/CentOSUpgradeTool]] without issue.\\
But after reboot i've started seeing following error "libpcre.so.0" not found.

After looking further it appeared to the issue with "grep" package.
After Successful reboot simply downgrade the grep package and error will disappear.

Also it is good idea to place selinux in permissive mode before you start upgrade.


==== Drupal Throw watchdog error ====
This error appear if variable name maxlength is exceeded.

To fix the error create/change value as suggested. (name varchar(48))

<code sql>
--
-- Table structure for table 'variable'
--

CREATE TABLE variable (
  name varchar(48) NOT NULL default '',
  value longtext NOT NULL,
  PRIMARY KEY (name)
)
</code>
==== Locale Issue on Linux ====

Following error get generated on "perl -v"
<code text>
perl: warning: Please check that your locale settings:
        LANGUAGE = (unset),
        LC_ALL = (unset),
</code>
In order to set locale you need to update following variable.
<code bash | /etc/sysconfig/i18n>
LANG="en_US.UTF-8"
</code>
That should do it.

==== Reset Zencart Password ====

Go to phpmyadmin - select Table "admin" from zencart database.\\
Select Edit for admin user and add following string in admin_pass field.

<code bash>
351683ea4e19efe34874b501fdbf9792:9b
</code>

Now you should be login as admin / admin.

==== Reset WordPress Password ====

Go to phpmyadmin - select table "wp-users" from wordpress database. \\
Select Edit for admin user and replace values with following string in user_pass field.

<code bash>
21232f297a57a5a743894a0e4a801fc3
</code>

Now you should be login as admin / admin.


==== SE Linux ====
Since most linux started providing SELinux there is many issue fixed by turning it off.\\
Eventually it has been introduced for really good reason. lets try to use it.

=== Issue with Zend Optimizer ===
After Default setup - Zend optimizer does not work on apache while php-cli working fine.
There is few command need to be executed in order to make it work.
- Add ZendOptimizer in Shared Context user.
<code bash>
#Enable Shared Context
chcon -t texrel_shlib_t /usr/lib64/php/modules/ZendOptimizer.so

#allow execstack and execmem for Zend´s binaries
execstack -c /usr/lib64/php/modules/ZendOptimizer.so
</code>

=== Reset Full Context ===
<code bash>
 genhomedircon
 touch /.autorelabel
 reboot 
</code>

=== Reset context on Specific Folder ===
<code bash>
  restorecon -Rv /var/www/html
</code>

=== Building Module from Type Enforcement ===
<code bash>
checkmodule -M -m -o mysql.mod mysql.te
semodule_package -o mysql.pp -m mysql.mod
semodule -i mysql.pp 
</code>

=== Web Application can not connect to db ===
This behavior can not get logged in audit.log some time.\\
which make it harder to troubleshoot. you can manually enabled network connection for db on http context.\\

<note> -P option is to make permanent change </note>

<code bash>
setsebool -P httpd_can_network_connect_db on
</code>
==== Telnet IMAP Test ====

To login to imap using telnet 
<code bash>
telnet <server> 143
01 LOGIN <username> <password>
02 LIST "" *
03 SELECT <mailbox>
</code>

You can see information about mailbox :
<code bash>
04 STATUS <mailbox> (<status_code>)
</code>
Following status code available : 
<code text>
MESSAGES
UNSEEN
RECENT
UIDNEXT
UIDVALIDITY
</code>

You can use "FETCH" command to view message.\\
Read following for any further information related to telnet / IMAP.\\

 - [[ http://documents.made-it.com/imapcmd.html | Telnet imap ]]\\
 - [[ http://bobpeers.com/technical/telnet_imap | In depth ]]


==== Internet Proxy Using SSH ====

This is simple step to use internet from another computer / location.\\

<code bash>
ssh -N -f -D 8822 <username>@<Remote_server>
</code>

Now setup all your browser to use proxy socks5 port 8822.\\
You are all set.

=== Allow Other computer ===
In order to allow other computer on network to access your proxy use following command.

<note warning>This is Open Proxy please use proper firewall rule to allow access.</note>

<code bash>
ssh -N -f -D 0.0.0.0:9933 k2patel@vedi.k2patel.in
</code>

Now setup other computer's browser to proxy socks5 host <your IP> port <9933>.\\
That should do it

==== Download java using wget ====
<code bash>
wget --no-check-certificate --no-cookies --header "Cookie: oraclelicense=accept-securebackup-cookie" http://download.oracle.com/otn-pub/java/jdk/8u51-b16/jdk-8u51-linux-i586.rpm
</code>

==== Force chronyc/chronyd/chrony time sync ====
<code bash>
chronyc -a 'burst 4/4'
chronyc -a makestep
</code>

==== Multiple BAR 13: no space for [io size 0x1000] ====

:!: Multiple BAR 13: no space for [io size 0x1000] messages seen on RHEL guest on VMWare ESX vCenter 6.0 host at boot.

best bet is to contact vmware, but temporary fix should be as follow
<code bash>
try booting with pci=nocrs kernel command line option.
This parameter is used to discard ACPI resource information for various devices.
</code>
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