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I have a centos server acting as router. It has two ethernet ports eth0 and eth1. eth0 is configured with the public static ip got from my ISP. I have my internal machines connected to this centos os router machine using LAN in eth1.

For example, assume that my public static ip given by my ISP is 123.45.567.89 and it is configured in eth0. In eth1 my internal machines are connected through LAN. Internal machines are in the ip range of 192.168.1.0 to 192.168.1.100

I have a web application running on one of my internal machines with IP 192.168.1.10 on port 8080. I can access this web app from my internal network by typing http://192.168.1.10:8080/ in a web browser. But I want to get this application from my public static ip given by ISP by simply typing http://123.45.567.89/ in the web browser. How can I achieve this? By port forwarding. Follow the below steps to achieve this.

I don't want to ssh to my linux server as root user. So I have disabled the direct root login through ssh. I am using a less privileged user to ssh to the server. But I don't want to give him sudo privilege. The only privileged command this user (less privileged user) should be able to run is to switch to root user. How can I achieve this?

I'm using Amazon Linux (which is actually centos based) in my ec2 instance. It comes with 'ec2-user' which has no password and but has sudo privilege and uses ssh key for login. I want to use password login for other users (and don't want to use ssh key for them)[So I can't disable password login "PasswordAuthentication  no" field in sshd_config file]. But I also want to set password for 'ec2-user' as I don't want to use sudo command without password. I have used below setup to achieve this.

Flite is text to speech engine for linux. It is based on festival speech synthesis system. Most of the linux sytems comes with flite in its package manager. It's just a apt-get on debian based or yum install in rpm based systems.

For example, you can install it on centos with below command:

We have seen how to remove a particular IP from the iptables rule. Now what if we want to remove all the iptables rule?

We can use the below command to remove all iptables rule.

I want to remove a rule from iptables which used to block one of the IPs to and from the server. How can I remove it? We will find it below.

IP which is blocked: 123.456.78.90


This will basically cut off all the tcp communication from and to my server for the IP 123.456.78.90