Ubuntu dependency issue while upgrading (linux-headers-generic (= 3.2.0.72.86) but 3.2.0.76.90 is to be installed)

Hi,

I faced an error while I ran the apt-get upgrade command on the Ubuntu 12.04 LTS server for fixing the Glibc vulnerability. The Exact error is


linux-header: depends on linux-headers-generic (= 3.2.0.72.86): but 3.2.0.76.90 is to be installed.


Below is the steps for fixing the issue. First check the header packages installed using the command

apt-get --get-selections |grep -i header


Then remove the below packages using the dpkg commands as below.


sudo dpkg -r linux-image-generic-pae
sudo dpkg -r linux-headers-generic-pae
sudo dpkg -r linux-generic-pae


Now run the below commands to upgrade


sudo apt-get -f install
sudo apt-get upgrade


This will installl the required packages and will replace the headers with new one and will resolve the dependency issues.



Thanks and Regards
Syamkumar.M

sasl login authentication failed authentication failure postfix webmin

Hi,

I faced one of the strange issue in which postfix was unable to send email from the domain users. There was a php mailer script that is sending emails by providing the smtp details(username, password and hostname of smtp server) to the phpmailer configuration file. But unfortunately the authentication was not working and so emails are not going from the code. Below is the steps to fix the issue.

1)First Check the log /var/log/maillog. I found the error as


postfix/smtpd[13573]: warning: localhost[127.0.0.1]: SASL LOGIN authentication failed: authentication failure


2)The postfix is using the saslauth authentication method. Theconfiguration options for starting saslauth with postfix is configured on the file

/etc/sysconfig/saslauthd

Open the configuration file and in the option field there will be a variable "r" is given

OPTIONS="-r"

Remove that option and set it as OPTIONS=""

There is no need for r in that .Below is the description for r.

 -r      Combine the realm with the login (with an '@' sign in between).
             e.g.  login: "foo" realm: "bar" will get passed as login:
             "foo@bar".  Note that the realm will still be passed, which may
             lead to unexpected behavior. 

Thanks and Regards

Syamkumar.M

How to enable Java Plugin to firefox on centos

Hi,

Below are the steps to install and enable java plugin for firefox. First we need to install java on the machine and then do the following steps to enable the plugin on the firefox.



root@test:~# ln -sf /opt/java/jre1.7.0_05/lib/i386/libnpjp2.so /usr/lib/mozilla/plugins/

root@test:~# export JAVA_HOME="/opt/java/jre1.7.0_05"

Testing the plugin.

root@test:~# firefox http://java.com/en/download/testjava.jsp

Regards
Syamkumar.M

/etc/rc.local not running on the boot

Hi,

   /etc/rc.local is the file which runs once the system boots up. If we need to run few commands immediately once the system starts up, we can do it by adding those commands in /etc/rc.local.

Last week I faced an issue in which the commands inside the rc.local was not working, once the system boot.  I tried starting and stopping the systems so many times and tried to change the settings of /etc/rc.local, but still it was not working.  Then I read in one of the Centos Forums that it was some issue with the first boot.

In my machine firstboot got hanged and init was not able to execute the content inside /etc/rc.local. Below is the steps to resolve it

check to see if firstboot is still running and kill it:


ps ax |grep firstboot
killall firstboot

This will kill the first boot .

Then switch the firstboot permenantly using chkconfig

chkconfig firstboot off


The first boot issue was caused by some of the software installations which may confuse the firstboot.

Regards
Syamkumar.M
 

How to change ulimit values permanently for a user in Centos

Hi,

ulimit is the parameter which defines the limits a process can use on a linux system.  It will provide control over the resources a user or a process in a shell can use.  You can list the current setting of ulimit values by login as your user and type the following commands

# ulimit -Hn
# ulimit -Sn

Default values should be 4096 and 1024 respectively.
 

So it will also determine the number of open files a user can open or edit. For increasing the ulimit, you need to change those paramentes in a configuration file called

/etc/security/limits.conf

If I need to change the ulimit value for my user on  a linux system. Then you should login to machine as root.

Open the above file in editor and then add the following content to it.

syam        soft nofile 9000
syam        hard nofile 65000


Now you should see the changes to the ulimit value for a user when you switch user from the root. But still the limit won't get reflected when user login as ssh with the password. We need to add the following steps to get the changes reflected for the user upon ssh login as user .

1. In /etc/pam.d/sshd added the line

session required pam_limits.so

2. In /etc/pam.d/login added the line

session required pam_limits.so

3. In /etc/ssh/sshd_config added

UsePAM yes

Now restart the sshd service

4. /etc/init.d/sshd restart

Now the ulimit values will be changed permenantly and you can see the values once you ssh into the machine as user.


ulimit -Hn
65000

ulimit -Sn

9000

Regards
Syamkumar.M