Posts filed under ‘Linux’

How to install only Security Updates on CentOS

Hi Folks

These commands are useful when you want to install  only the sceurity updates  in order to meet any compliance such as PCI

First you need to install the  security plugin for the Yum

#yum install yum-security

Once it installed

#yum  list-security —–> To check the security updates avaialable

#yum update –security  ——> To install  only the Securuty Updates.

Good Luck..

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February 3, 2013 at 8:16 am Leave a comment

How to idenitfy a process ID using the TCP Port

Recently i had an issue  in one of my linux machines, where I was unable to start the acronis_agent service which listens on TCP Port ;

Later I realised  that already so many processes are listening on the TCP port.

To check the open connection for a TCP  port

# netstat -an | grep 9876   ( In my case acronis_agent uses TCP 9876)

It was showing multiple connections………….

To check the PID(Process ID ) for all the sessions  which are using the port 9876

#lsof -i TCP:9876

finally you could use  the  almighty command “kill -9 PID”  …. boom everything became normal.

October 23, 2011 at 1:57 pm Leave a comment

Linux Guide

Anyy body looking for a brief documentation on  RHEL can make use of the below files , which I made for my linux class

Introduction to Linux

LinuxGuide_v3

October 23, 2011 at 11:09 am Leave a comment

Sendmail STARTTLS: read error=generic SSL error

I was having an issue with my sendmail server where I receives this error which will cause the sendmails logs grow drastically and fill the /var partition.

further it will stop the mail flow ( when /var partition is full)

So i wrote this bash script which does the following;

– look for this error in the maillog

– when it finds it will kill the sendmail process which is causing the  sendmail to log multiple     entries in the logfile and will restart the sendmail and syslog daemons.

anybody is welcome to give their comment on improvements or any drawbacks on this script good luck…….

#!/bin/bash
LAST=’last message’
SSL=”STARTTLS: read error=generic SSL error (0)”
S1=”0″

cp /var/log/maillog /home/muralee/log_check/maillog
grep “STARTTLS: read error=generic SSL error (0)”   /home/muralee/log_check/maillog |awk ‘/sendmail/ {print $5}’ | tr -d [digit:]”sendmail[]” > records.txt
#grep “STARTTLS: read error=generic SSL error (0)”   /home/muralee/maillog.1 |awk ‘/sendmail/ {print $5}’ | tr -d [digit:]”sendmail[]” > records.txt
results=$(wc -l records.txt | awk ‘/records/ {print $1}’)
if [[ $results -eq 0 ]];then
echo “Sendmail is Fine”
fi
if [[ $results -ne 0 ]]; then
pkill sendmail
/etc/init.d/sendmail restart
/etc/init.d/syslog restart
echo “Problem resolved”
cat /dev/null > records.txt

September 20, 2011 at 12:14 pm Leave a comment

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