Administration

Use a File for Additional Swap Space

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The following dd command example creates a swap file with the name “swapfile” under /root directory with a size of 8192MB (8GB). To create the swap space (non-persistent): Change the permission of the swap file so that only root can access it. Make this file as a swap file using mkswap command. Enable the newly … Read more

Disk I/O Stats in linux

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Sysstat

For disk I/O trending there are a few options. the sar command from sysstat. By default, it gives output like this:

# sar
Linux 2.6.32-642.11.1.el6.x86_64 (test.geekdecoder.com)    01/26/2017      _x86_64_        (2 CPU)

12:00:01 AM     CPU     %user     %nice   %system   %iowait    %steal     %idle
12:10:01 AM     all      0.03      0.00      0.03      0.09      0.00     99.85
12:20:01 AM     all      0.27      0.00      0.04      0.00      0.00     99.69
12:30:01 AM     all      0.33      0.00      0.05      0.00      0.00     99.62
12:40:01 AM     all      1.01      0.00      0.18      1.18      0.00     97.63
12:50:01 AM     all      0.15      0.00      0.04      0.00      0.00     99.80
01:00:01 AM     all      0.16      0.00      0.03      0.00      0.00     99.80
01:10:01 AM     all      0.22      0.00      0.04      0.00      0.00     99.74
01:20:01 AM     all      0.36      0.00      0.05      0.00      0.00     99.59
01:30:01 AM     all      0.23      0.00      0.04      0.00      0.00     99.74
01:40:01 AM     all      0.70      0.00      0.25      6.23      0.00     92.82
01:50:01 AM     all      0.13      0.00      0.03      0.00      0.00     99.83
02:00:01 AM     all      0.16      0.00      0.04      0.00      0.00     99.80
02:10:01 AM     all      0.21      0.00      0.04      0.00      0.00     99.75
02:20:01 AM     all      0.30      0.00      0.04      0.00      0.00     99.66
02:30:01 AM     all      0.14      0.00      0.03      0.00      0.00     99.83
02:40:01 AM     all      0.20      0.00      0.03      0.00      0.00     99.76
02:50:01 AM     all      0.32      0.00      0.05      0.00      0.00     99.63
03:00:01 AM     all      0.21      0.00      0.03      0.00      0.00     99.76
03:10:01 AM     all      0.19      0.00      0.04      0.00      0.00     99.77
03:20:01 AM     all      0.12      8.44      2.69     10.79      0.00     77.96
03:30:01 AM     all      0.13      4.52      8.36      0.30      0.00     86.69
03:40:01 AM     all      0.48      0.00      0.05      0.02      0.00     99.45
03:50:01 AM     all      0.15      0.00      0.04      0.01      0.00     99.80
04:00:01 AM     all      0.13      0.00      0.03      0.00      0.00     99.84
04:10:01 AM     all      0.48      0.00      0.06      0.04      0.00     99.43
04:20:01 AM     all      0.17      0.00      0.05      0.11      0.00     99.67
04:30:01 AM     all      0.22      0.00      0.04      0.00      0.00     99.74
04:40:01 AM     all      0.89      0.00      0.08      0.16      0.00     98.87
04:50:01 AM     all      0.55      0.00      0.07      0.05      0.00     99.34
05:00:01 AM     all      0.11      0.00      0.04      0.01      0.00     99.85
05:10:01 AM     all      0.09      0.00      0.03      0.00      0.00     99.87
05:20:01 AM     all      0.17      0.00      0.04      0.00      0.00     99.80
05:30:01 AM     all      0.27      0.00      0.05      0.08      0.00     99.60

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Find all files modified within 30 days and then parsed that for base64 decodes (used to encrypt/hide coding)

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If your site is hacked, the check for edited files. Find all files modified within 30 days and then parsed that for base64 decodes (used to encrypt/hide coding) Find the coding itself # cd /home/domain/public_html # find . -type f -ctime -30 -iname "*.php" -exec grep "base64_decode" {} \; Results # find . -type f … Read more

IP Lookup with CLI Linux

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nstall geoiplookup on Debian, Ubuntu or Linux Mint: $ sudo apt-get install geoip-bin To install geoiplookup on Fedora: $ sudo yum install geoip To install geoiplookup on CentOS, first enable EPEL repository $ sudo yum install epel-release then use yum command: $ sudo yum install geoip The default installation of geoiplookup comes with GeoIP.dat database … Read more

Ifconfig Command Not Found In CentOS 7

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CentOS 7 minimal systems, use the commands “ip addr” and “ip link” to find the details of a network interface card. To know the statistics use “ip -s link”. To view the details of the network interface cards, enter the following commands: # ip addr To view the statistics of your network interfaces, enter the … Read more

Time stamped bash history logging

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Timestamped bash history logging may be a great idea for logging changes. An example would look like this: Mar 28 15:08:26 database root: root@192.168.1.1 [10882]: shutdown -r now [0] Mar 28 15:08:31 database root: root@192.168.1.1 [10882]: cd /var/log [0] This can be done by adding 2 lines to the root .bashrc file or as a … Read more

Sync Date on CentOS 6 VM servers

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My VM on ESXi have all different dates. Here is how toset them the same. First, you’ll need to install NTP. For Debian or Ubuntu, that would be this command: # sudo apt-get install ntp For Redhat or CentOS, you’ll need to use this one: # yum install ntp Then you’ll want to edit the … Read more

Drown Attack

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Check your Site at https://drownattack.com/#test or run the following: http (replace IP with your server ip) openssl s_client -connect 192.168.1.1:443 -ssl2 postfix or other email MTA openssl s_client -connect xxxxxxxxxxxxx.com:25 -starttls smtp -ssl2 Check your version # openssl version OpenSSL 1.0.1e-fips 11 Feb 2013 To protect against DROWN, server operators need to ensure that their … Read more