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By sysconfig at 2006-11-06 02:14
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To get the list of username with its user ID in formatted way:
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# awk -F":" '{ print "username: " $1 "\t\tuid:" $3 }' /etc/passwd
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Find the particular string from the list of files in current directory:
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# cd /etc
# for i in $(find -type f); do grep -iH nfsnobody $i; done
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Or
Get the no of occurrences of particular word in file:
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# awk '/ServerName/ {i=i+1} END {print i}' /etc/httpd/conf/httpd.conf
# grep ServerName /etc/httpd/conf/httpd.conf
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To delete resources of semaphore arrays from memory:
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# ipcs -s | grep apache | perl -e 'while (<STDIN>) { @a=split(/\s+/); print`ipcrm sem $a[1]`}'
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To check whether perl module is installed correctly or not:
If all is correct then output of this command nothing
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# perl -e 'require Mail::SPF::Query'
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To install CPAN module:
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#cpan
cpan> install Mail::SPF::Query
CPAN: Storable loaded ok
Going to read /root/.cpan/Metadata
Database was generated on Thu, 24 Nov 2005 14:54:20 GMT
Mail::SPF::Query is up to date.
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To get the list of IP addresses in the server:
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#ifconfig | grep -vw inet6 | grep -w inet | cut -d : -f 2 | cut -d \ -f 1
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Find list of IP address along with eth device and network mask:
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# ifconfig | cut -d " " -f1,12,16 | grep -A 1 eth | tr -d - | tr -s "\n" |sed -e :a -e N -e 's/\n/ /'
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Know the performance of your HardDisk:
change the device address as per your servers configuration
Get the customized output of raw accesslog of httpd:
Navigate the folder where your http access log reside
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# tail -f access_log | awk '{if ($11 ~"\"-\"") print $1, $7, $12; else print $1, $10, $11, $12}'
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The details of the present http connections can be found by using:
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# netstat -plan | grep ":80 " | awk {'print $5'} |awk -F: {'print $1'}|sort
# cat /proc/net/ip_conntrack | grep "port=80" | wc -l
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Number of connection from perticular IP addfess:
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# netstat -ntu | awk '{print $5}'| cut -d: -f1 | sort | uniq -c | sort -nr | more
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No of conections:
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# netstat -alntp
#/sbin/ldconfig /usr/local/lib - Update the system linker cache
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Port scanning using nmap:
You can customized it to get more informative output
instead host localhost, it could be IP address of another server which is in question
You can execute bash command a certain number of times by using something similar to the following:
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n=0;while test -$n -gt -10; do echo n=$n; n=$[$n+1]; done
That code will print "n=0", "n=1", and so on 10 times.
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Only get the listing of directories:
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ls -F $1 | grep \/ | sed -e 's/\/$/4/g'
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Real Time Network Activity Examples:
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root# watch -d "netstat -nalp |grep -v DGRAM |grep -v STREAM |grep -v LISTEN"
root# watch "netstat -nalp"|grep ":TCP PORT Number"
root# watch "netstat -nalp"|grep ":22"
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1. For check ssh failure log ( in GNU/Linux Debian)
#/bin/cat /var/log/auth.log |grep sshd:auth |grep failure |awk '{print $1"-" $2 "-" $3 "-->" $12 "->" $14 "->" $15}'#for a in $( ps aux | grep "some-thing-text" | awk '{ print $2 }'); do kill $a; done;#for a in $( ps aux | grep "/USR/SBIN/CRON" | awk '{ print $2 }'); do kill $a; done;