Category Archives: Linux

How to resolve in Linux

While running commands with the help of sudo if you are getting following error the you have to add that user to sudo group : is not in the sudoers file. This incident will be reported adduser <username> sudo   … Continue reading

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Understanding commands

Cut command: cut -d : -f1,2 /etc/passwd delimiter is specified by -d option and in this command the delimiter is : -f option specifies to print 1,2 match cd command: cd command is used to change the directory. “.” represents … Continue reading

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FreeBSD commands

The purpose of this post is to provide useful command needed while working on freebsd: How to check ipv4 routing table: netstat -rn -4 How to install a package: pkg install apache24 How to get list of software installed in … Continue reading

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Understanding ls command output

ls command provides information about a file.  In Linux everything is represented as a file. A sample output of ls -lh is give below.   Total: show total size of the folder. File type: First field in the output is … Continue reading

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iptables in ubuntu

iptables can be used to inspect, modify, forward, redirect, and/or drop IPv4 packets. There are five table in iptables: 1> Raw 2> Filter 3> Nat 4>Mangle 5> Security To view these table we can use following command: iptables -t raw … Continue reading

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Understanding ntpq output

In Ubuntu NTP configuration is kept under file /etc/ntp.conf ntpq> peer remote refid st t when poll reach delay offset jitter ============================================================================== ntp.ubuntu.com .POOL. 16 p – 64 0 0.000 0.000 0.000 *123.108.200.124 210.23.25.77 2 u 83 128 375 241.212 … Continue reading

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Routing and NAT in Ubuntu with the help of iptables

This post can be used in case when we have a Device having Ubuntu OS and with two or more NIC. One NIC is having internet connection and on another NIC some host/devices are connected. Goal of this post is … Continue reading

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