Deleting Single Iptables Rule

I look at my iptables rules

iptables -L

and get this

Chain INPUT (policy ACCEPT)
target     prot opt source               destination        
ACCEPT     all  --  anywhere             anywhere            state RELATED,ESTABLISHED
ACCEPT     icmp --  anywhere             anywhere           
ACCEPT     all  --  anywhere             anywhere           

Chain FORWARD (policy ACCEPT)
target     prot opt source               destination        

Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination

For example I make rule to accept port 80, so I do this

iptables -I INPUT 3 -p tcp --dport 80 -j ACCEPT

and then iptables -L give us this

Chain INPUT (policy ACCEPT)
target     prot opt source               destination        
ACCEPT     all  --  anywhere             anywhere            state RELATED,ESTABLISHED
ACCEPT     icmp --  anywhere             anywhere           
ACCEPT     tcp  --  anywhere             anywhere            tcp dpt:http
ACCEPT     all  --  anywhere             anywhere

Look at third line, there is rule for accepting connection from port 80. The rule inserted in third line because I use 3 in this rule

 iptables -I INPUT 3 -p tcp --dport 80 -j ACCEPT

If we want to delete this single rule, do

iptables -D INPUT 3

So iptables -L give us

Chain INPUT (policy ACCEPT)
target     prot opt source               destination        
ACCEPT     all  --  anywhere             anywhere            state RELATED,ESTABLISHED
ACCEPT     icmp --  anywhere             anywhere           
ACCEPT     all  --  anywhere             anywhere

Source:
http://major.io/2007/02/09/delete-single-iptables-rules/

Upgrade Ubuntu 12.04 to Ubuntu 14.04

Ensure that your Ubuntu is up to date

sudo apt-get update && sudo apt-get upgrade -y

Install update manager core

sudo apt-get install update-manager-core -y

 Upgrade your Ubuntu

sudo do-release-upgrade -d

And follow next instruction carefully.....

Source:
http://www.namhuy.net/2853/upgrade-ubuntu-12-04-lts-ubuntu-14-04-lts.html

Grant Root Access To Additional User FreeBSD

Just add user to group wheel with this

pw user mod username -G wheel

For example I add user akhfa to wheel group

pw user mod akhfa -G wheel

If you do it well, if you type

groups akhfa

you will get

akhfa       wheel

Source:
http://www.cyberciti.biz/tips/freebsd-becoming-super-user-su-or-enabling-su-access-to-user.html

Install Nano On FreeBSD

Go to nano directory

cd /usr/ports/editors/nano

Compile and install nano

make install clean

Make symbolic link

ln -s /usr/local/bin/nano /usr/bin/nano

Source:
http://blog.bobbyallen.me/2012/05/28/how-to-install-nano-on-freebsd/

Updating FreeBSD

To update your FreeBSD, do this

freebsd-update fetch

freebsd-update install

If something wrong, you can cancel update by

freebsd-update  rollback

Source:
http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/updating-upgrading-freebsdupdate.html

Install Htop On CentOS

Htop, a process manager based on command line interface, is a powerful tool to manage process from terminal.

Enable Remote Access To Mysql Database Server Or On VPS Ubuntu

If you want to make application with remote database, you will need to grant database on your server to be accessed by your application. Now I will tell you how to grant access so your application can use mysql from your server.

Fix GPG Error Ubuntu

Sometimes you can find like this on terminal when updating repository

W: There is no public key available for the following key IDs:
3B4FE6ACC0B21F32

If you found it, fix with this

sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 3B4FE6ACC0B21F32

And then try "apt-get update" again

Install Dropbear And Change Dropbear Port On Ubuntu

Make sure that your Ubuntu is up to date

sudo apt-get update && sudo apt-get upgrade -y

To install Dropbear, run this on terminal

sudo apt-get install dropbear

 To start and change dropbear port, make sure nano was installed and do this