How to Set Up A Firewall Using Iptables on Ubuntu 16.04

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This guide will walk you through the steps for setting up a firewall using iptables in Ubuntu 16.04. We’ll show you some common commands for manipulating the firewall, and teach you how to create your own rules.

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What’s My IP Address?

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As part of our Web Hosting Toolkit, our Liquid Web IP Checker makes it easier than ever to identify IT issues. IP addresses are the unique numbers assigned to every computer that connects to the Internet. When troubleshooting connectivity issues, checking your computer’s IP address is the first step in identifying possible network issues. Correctly identifying your public IP address allows you (and our Support technicians) to find information on the server and it’s log files to pinpoint possible issues between your computer and server.

 

Finding Your Public IP Address

As the first piece of information in the connection between your local workstation and server, your Public IP address is critical to the information gathering process. Fortunately, you don’t need to navigate complex networking configurations on your computer to find the public IP address; you need to ask an external server what IP identifies with your connection. You can do this by using Liquid Web’s Internet Web Hosting Toolkit. Go to the toolkit website and click on IP Checker. You’ll immediately be shown the public IP address that your computer is reporting.

lwtoolkit ipcheckerYou can also get additional information about how your computer is identifying itself (including location, operating system, and browser details) by clicking on the link in the extra information area. This information can help identify website compatibility issues based on various user settings.lwtoolkit ipchecker more detail

How Do I Know If My IP Is Public or Private?

Most computers that are attached to a network have both a Public and a Private IP address. The IP address assigned to your computer by your router or wireless modem is generally a Private IP and typically is in one of two “reserved” ranges: either 10.x.x.x or 192.x.x.x. These Private IP ranges allow all of the devices in your local network to communicate with each other. When connecting with devices outside of your local network, your router will provide a Public IP address to outgoing traffic (often all of the devices inside your network will “share” the same Public IP address). The Public IP address allows computers across the Internet to identify each other and communicate effectively. To troubleshoot networking issues, we’ll need to find the Public IP address that your computer is broadcasting to the Internet. With the Public IP you can search through the firewall and server logs to find connection attempts and identify possible issues that may be preventing access.

 

How Do I Know If MY IP Address Is Blocked?

Most servers have software that works to detect and prevent possible malicious activity. Sometimes this software is part of the firewall or another application, but the result is the same: computers that fail to satisfy this software will be blocked from accessing the server. These blocks can occur due to repeated failed login attempts or even by opening too many connections at the same time (this often happens when transferring a large amount of data via FTP).

Security software typically blocks IPs by an escalating scale. That is, an offending IP address will be blocked for a short amount of time on the first offense, but the blocks will increase in length as the behavior continues until the IP address is permanently barred. An incorrect password saved in an FTP client can result in a permanent block in a short amount of time. If you suspect your server is blocking your IP, you may be able to remove the block automatically. For more information on unblocking your IP, see Unblocking Your IP Address.

Now that you’ve got your Public IP address, you can check your server logs for failed connection attempts or other errors that may indicate why you are having trouble connecting. Or you can share that information with one of Liquid Web’s Most Helpful Humans in Hosting and they can help resolve whatever connectivity issues you are experiencing.

To learn more about the tools Liquidweb offers, submit a ticket with us via our support@liquidweb.com email, give us a call at 800-580-4985 or, open a chat with us to speak to one of our skilled Level 3 Support Admins today!

How Do I Use Liquid Web’s Hosting Toolkit?

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If there is one truth in the world of web hosting, it is that we always need more information. Information about configurations, servers, connections, delivery speeds and networking is essential in troubleshooting and optimizing our web presence. While this kind of information can be gathered from various providers and sites across the Internet, Liquid Web has developed a one stop shop toolkit to gather some of the most vital troubleshooting tools in one convenient interface designed to make your life easier.

The Liquid Web Internet Webhosting Toolkit provides you with the data you need to verify connectivity, identify DNS issues, and test web page performance. We’ll continue to develop and share new tools that will make your job easier; it’s one of the ways that we are working to be the Most Helpful Humans in Hosting. Continue reading “How Do I Use Liquid Web’s Hosting Toolkit?”

Troubleshooting: Locked Out of RDP

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How Do I Get Back Into RDP?

You may be working from a local machine that has an IP that is not scoped on that RDP port, making it impossible for you to gain remote access to add the IP address to the RDP rule’s scope. Do not fret; there is a simple and quick way to add your IP to the RDP scoping (or any others entities such as MySQL or MSSQL) right through your Plesk interface in your local browser. You can watch this video, or scroll down for step-by-step directions.

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An Introduction to Firewalld

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In some ways, firewalld on systemd systems is easier to manage and configure than iptables. There are, for the most part, no long series of chains, jumps, accepts and denies that you need to memorize in order to get firewalld up and running in a basic configuration. The rules are simple and straightforward, but there is no reason you cannot still have all the power that iptables afforded. Continue reading “An Introduction to Firewalld”

Useful Command Line for Linux Admins

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The command line terminal, or shell on your Linux server, is a potent tool for deciphering activity on the server, performing operations, or making system changes. But with several thousand executable binaries installed by default, what tools are useful, and how should you use them safely? Continue reading “Useful Command Line for Linux Admins”

Improving Security for your Remote Desktop Connection

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Remote Desktop Protocol (RDP) is the easiest and most common method for managing a Windows server. Included in all versions of Windows server and has a built-in client on all Windows desktops. There are also free applications available for Macintosh and Linux based desktops. Unfortunately, because it is so widely used, RDP is also the target of a large number of brute force attacks on the server. Malicious users will use compromised computers to attempt to connect to your server using RDP. Even if the attack is unsuccessful in guessing your administrator password, just the flood of attempted connections can cause instability and other performance issues on your server. Fortunately, there are some approaches you can use to minimize your exposure to these types of attacks. Continue reading “Improving Security for your Remote Desktop Connection”

Whitelisting in ModSecurity

Reading Time: 6 minutes

Broken down into two parts our article’s first section hits on “how to whitelist IPs or URIs,” for people who are somewhat familiar with ModSecurity but want to know further about the process. Our second section examines why we configure ModSecurity and how to prevent the security of the server from getting in the way of our work. If you have a Fully Managed Liquid Web server reach out to our Heroic Support team for assistance with whitelisting! Continue reading “Whitelisting in ModSecurity”

Difference Between ipv4 and ipv6

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The Internet Protocol (IP) system designates how networked devices can address one another across the internet. The first major version of IP, IPv4, was deployed to the public ARPANET in 1983. IPv4 uses 4 one byte segments to designate a devices address, this 32-bit address space allows for 232 addresses to be used in total. The next major iteration of IP is called IPv6 and it uses a 128-bit address space allowing for significantly more IP addresses to be assigned. Continue reading “Difference Between ipv4 and ipv6”