What is Round-Trip Time (RTT)?

Round-Trip Time is a network performance metric representing the time it takes for a data packet to travel from the source to the destination and back to the source. It is often measured in milliseconds (ms) and is a crucial parameter for determining the quality and efficiency of network connections.

To understand the concept of RTT, imagine sending a letter to a friend through the postal service. The time it takes for the letter to reach your friend and for your friend to send a reply back to you forms the Round-Trip Time for your communication. Similarly, in computer networks, data packets are like those letters, and RTT represents the time it takes for them to complete a round trip.

How Does it Work?

The concept of RTT can be best understood by considering the journey of data packets across a network. When you request information from a web server, for example, your device sends out a data packet holding your request. This packet travels through various network devices in between, such as routers and switches, before reaching the destination server. Once the server processes your request and prepares a response, it sends a data packet back to your device.

Round-Trip Time is determined by the time it takes for this data packet to travel from your device to the server (the outbound trip) and then back from the server to your device (the inbound trip). The total RTT is the sum of these two one-way trips.

Let’s break down the journey of a data packet into several steps so you can better understand the RTT:

1. Sending the Packet: You initiate an action on your device that requires data transmission. For example, this could be sending an email, loading a webpage, or making a video call.
2. Packet Travel: The data packet travels from your device to a server, typically passing through multiple network nodes and routers along the way. These middle points play a significant role in determining the RTT.
3. Processing Time: The server receives the packet, processes the request, and sends a response back to your device. This processing time at both ends also contributes to the Round-Trip Time.
4. Return Journey: The response packet makes its way back to your device through the same network infrastructure, facing potential delays on the route.
5. Calculation: It is calculated by adding up the time taken for the packet to travel from your device to the server (the outbound trip) and the time it takes for the response to return (the inbound trip).

Why does it matter?

At first look, Round-Trip Time (RTT) might seem like technical terminology, but its importance extends to various aspects of our digital lives. It matters for many reasons, which include the following:

• User Experience

For everyday internet users, RTT influences the sensed speed and responsiveness of online activities. Low Round-Trip Time values lead to a seamless experience, while high RTT can result in frustrating delays and lag during tasks like video streaming, online gaming, or live chats.

• Network Efficiency

Network administrators and service providers closely monitor RTT to assess network performance and troubleshoot issues. By identifying bottlenecks and areas with high RTT, they can optimize their infrastructure for better efficiency.

• Real-Time Applications

Applications that rely on real-time data transmission, such as VoIP calls, video conferencing, and online gaming, are highly sensitive to RTT. Low RTT is crucial for smooth, interruption-free interactions.

• Security

In cybersecurity, Round-Trip Time plays a role in detecting network anomalies and potential threats. Unusually high RTT values can be a sign of malicious activity or network congestion.

Tools for Measuring RTT

Measuring Round-Trip Time is essential for understanding network performance. Two of the most commonly used tools are Ping and Traceroute. Here’s how to use them:

• Ping command

The Ping command is a fundamental tool available on most operating systems. It measures RTT by sending Internet Control Message Protocol (ICMP) echo requests to a specified IP address. It calculates the time it takes for a packet to travel to the target and back, providing the RTT in milliseconds. This tool is valuable for basic network diagnostics, helping you identify if a host is reachable and how long it takes to communicate with it. You can easily use it by following these steps:

1. Open Command Prompt (Windows) or Terminal (macOS/Linux).
2. Type “ping” and the target domain or IP address. Here is an example: ping domain.com
3. Press Enter.

The output will display the RTT in milliseconds for each packet sent.

• Traceroute/Tracert

Traceroute (or Tracert in Windows) is a diagnostic tool that goes beyond just measuring RTT. It traces the entire path a packet takes to reach its destination, displaying each hop along the route and the RTT to each router. That way, it helps identify where delays or packet loss occur in the network, making it a crucial tool for finding issues in complex networks. To utilize it, follow the steps below:

1. Open Command Prompt (Windows) or Terminal (macOS/Linux).
2. Type “tracert” (Windows) or “traceroute” (macOS/Linux) followed by the target domain or IP address. Here is an illustration: traceroute domain.com
3. Press Enter.

The output will show the RTT for each hop along the route to the destination.

Factors Affecting Round-Trip Time (RTT)

Several factors can influence the metric, both positively and negatively. Therefore, understanding these factors is crucial, and it could be very beneficial for optimizing network performance:

• Distance: The physical distance between the source and destination plays a significant role. Longer distances result in higher RTT due to the time it takes for data to travel the network.
• Network Congestion: When a network experiences high volumes of traffic or congestion, data packets may be delayed as they wait for their turn to be processed. As a result, it can lead to packet delays and increased RTT.
• Routing: The path a packet takes through the network can significantly affect RTT. Efficient routing algorithms can reduce the time, while not-so-optimal routing choices can increase it.
• Packet Loss: Packet loss during transmission can occur due to various reasons, such as network errors or congestion. When lost, packets need to be retransmitted, which can seriously affect the Round-Trip Time.
• Transmission Medium: It is a critical factor influencing RTT, and its characteristics can vary widely based on the specific medium being used. Fiber optic cables generally offer low RTT due to the speed of light in the medium and low signal loss. In contrast, wireless mediums can introduce variable delays depending on environmental factors and network conditions.

How to improve it?

Improving Round-Trip Time (RTT) is a critical goal for network administrators and service providers looking to enhance user experiences and optimize their digital operations. While some factors affecting it are beyond our control, there are strategies and practices to optimize Round-Trip Time for a smoother online experience:

• Optimize Routing: Network administrators can optimize routing to reduce the number of hops data packets take to reach their destination. This can be achieved through efficient routing protocols and load balancing.
• Optimize Network Infrastructure: For businesses, investing in efficient network infrastructure, including high-performance routers and switches, can reduce internal network delays and improve RTT.
• Upgrade Hardware and Software: Keeping networking equipment and software up-to-date ensures that you benefit from the latest technologies and optimizations that can decrease RTT.
• Implement Caching: Caching frequently requested data closer to end-users can dramatically reduce the need for data to travel long distances. The result really helps with lowering RTT.
• Monitor and Troubleshoot: Regularly monitor your network for signs of congestion or packet loss. If issues arise, take steps to troubleshoot and resolve them promptly.

Discover ClouDNS Monitoring service!

RTT vs Latency

RTT and latency are related but not identical metrics in networking. Latency is the time it takes for a packet to travel from the source to the destination, often referred to as a one-way delay. RTT, on the other hand, measures the total time it takes for a packet to go to the destination and for a response to come back to the source.

It is important to mention that RTT is not always exactly twice the latency. Factors such as network congestion, processing delays at routers, and asymmetrical routing can cause RTT to differ from simply doubling the latency. For example, if the route from source to destination is more congested or longer in one direction, the round-trip time might be significantly higher than twice the latency.

Conclusion

Round-Trip Time (RTT) is the silent force that shapes our online experiences. From the seamless loading of web pages to the quality of our video calls, RTT plays a pivotal role in ensuring that digital interactions happen at the speed of thought. As we continue to rely on the Internet for work, entertainment, and communication, understanding and optimizing this metric will be crucial for both end-users and network administrators. By reducing it through strategies, we can have a faster, more responsive digital world where our online activities are limited only by our imagination, not by lag.

The post Round-Trip Time (RTT): What It Is and Why It Matters appeared first on ClouDNS Blog.

Historical evolution of the Ping of Death attack

The Ping of Death (PoD) attack has a rich history. In the early days of the internet, networks and devices were less sophisticated and more susceptible to various forms of cyber attacks, including the Ping of Death. The original PoD attack involved sending malformed or oversized packets using the ICMP protocol, which could crash systems or cause network interruptions. This vulnerability was particularly prevalent in older operating systems that didn’t properly handle these packets.

Over time, as operating systems and network hardware became more advanced, they were patched to resist these types of attacks. This led to the evolution of PoD tactics, with attackers finding new methods to exploit different vulnerabilities within network protocols and systems.

What is Ping of Death (PoD)?

Ping of Death (PoD) is a popular type of DoS (Denial of Service) attack. The cybercriminal that initiates it aims to destabilize or completely crash the device, server, or service of the victim. In order to achieve that, the attacker sends malformed or oversized packets with the help of the Ping command. Unfortunately, the moment when the victim’s system processes the data packet, the system faces an error that forces it to crash.

The concept of the Ping of Death (PoD) attack is commonly compared to a mail bomb: If the recipient opens the package, a mechanism is triggered, and the target is attacked or completely destroyed. 

On the other hand, the Ping command, from which the attack gets its name, is a popular tool for testing the reachability of a network. The command is designated based on the Internet Control Message Protocol (ICMP), which serves for providing status information on the Internet.

Ping of Death attacks could occur on patched and unpatched systems that have legacy weaknesses on the target systems. The cybercriminal does not even need any additional details about the target’s device or its operating system (OS). The only required information is the IP address and nothing else.

So, now that you are familiar with what a Ping of Death attack is, it is time to dive a little bit deeper and explain how it actually works.

How does it work?

To enable a Ping of Death attack, criminals use the ping command to send oversized data packets to their target to destabilize or crash it. 

An Internet Control Message Protocol (ICMP) echo-reply message, also known as “ping”, is a network utility that serves for testing a network connection. It sends out pings and waits for an ICMP echo reply, which contains information about the condition and environment of a precise network. That means the connection is successful.

In order to launch a Ping of Death attack, attackers create an ICMP packet that’s larger than allowed. The packet is separated into smaller pieces for transportation. When the receiver puts them back together, the maximum allowed size is exceeded. That leads to an overflow in the memory buffer, forcing the system to crash.

To bring it all together, the maximum packet size for IPv4 is 65,535 bytes, including a total payload of 84 bytes. Thus in order to launch a PoD attack, cybercriminals send bigger than 110k ping packets to the victim’s device.  

Attackers can also perform this DoS attack over the User Datagram Protocol (UDP), Internet Packet Exchange (IPX), and Transmission Control Protocol (TCP). Anything that sends an Internet Protocol datagram can be put into action.

Here’s what a Ping of Death looks like on Windows and Linux :

Ping of Death Windows:

ping <ip address> -1 65500 -w 1 -n 1

Ping of Death Linux:

ping <ip address> -s 65500 -t 1 -n 1

Does the Ping of Death still work?

The Ping of Death (PoD) is actually quite an old attack that first occurred back in the mid-1990s. Since then, the majority of devices and computers have been protected against these types of attacks. Additionally, a lot of websites keep blocking ICMP ping messages in order to stop and avoid future variations of this DoS attack.

Yet, an organization’s defenses can weaken due to malicious content on any computer, server, or network and still be vulnerable to the threat. It is threatened by this attack if the following are unpatched:

• Vulnerable Legacy Equipment
• Kernel driver in TCPIP.sys
• Windows XP and Windows Server 2013 copies on systems already vulnerable to a weakness in OpenType fonts

Recent Ping of Death attacks

Let’s explain a little bit more about some of the recent appearances of the Ping of Death attack.

• PoD attacks officially made their return in August 2013 by threatening the Internet Protocol version 6 (IPv6) networks. Then the attacker took advantage of a weakness in the soon-to-be discontinued Windows XP and Windows Server 2013 operating systems, more precisely in OpenType fonts. A flaw in the IPv6 implementation of ICMP allowed the attacker to send massive ping requests that smashed the victim when it reassembled the packets. This precise threat could have been avoided simply by disabling IPv6.
• Back in October 2020 was found a flaw in the Windows component TCPIP.sys, which represents a Kernel driver that would get to the core of any Windows system if used for an attacker’s advantage. The result would be a hard crash and total shutdown of the device, followed by a reboot. Yet, it was a bit complicated for cyber criminals to actually use this vulnerability. So, users started patching their devices in order to prevent the threat. 

The Ping of Death seems to be a simple and small-in-scale attack, and that makes it an efficient weapon against particular machines. Yet, we should not underestimate it! If a group of devices comes together, there is a great chance a handful of these to bring down a website that does not have the suitable infrastructure to deal with this threat. These examples from the past indeed show that Ping of Death could still appear. Therefore, it is highly recommended for organizations to take the needed measures to protect themselves.

Preventing measures against PoD attack

There are several ways you could prevent, stop and protect yourself from a Ping of Death (PoD) attack. Most of them are easy and simple to implement. Let’s see which are they and how they can help you avoid Ping of Death. 

• Configure your firewall to block ICMP Ping Messages. This will protect your network from the PoD threat, yet it will also stop legitimate pings. Additionally, invalid packet attacks can be launched through other listening ports, such as FTP (File Transfer Protocol). So, it is not an ideal solution.
• Monitoring with ICMP Ping. If you don’t like the idea of completely blocking ICMP Ping messages, Ping monitoring which is a part of the ClouDNS Monitoring service, would be your preferred solution. It spots network problems quickly and helps you improve your overall security. 

Suggested article: What ICMP Ping traffic monitoring is?

• Implement DDoS Protection. A DDoS protection service provides you with a brilliant technique for network security and protecting against DDoS attacks and Ping of Death attacks.
• Update your software regularly. When a flaw appears, commonly shortly after, the patches are released too. It is important to accept them and keep your device safe.
• Implement a buffer. Improve your capability to accept large packets with an overflow buffer. 
• Filter your traffic. You can stop just fragmented pings from reaching any device in the network. That will allow you to use the ping command’s utility without being at risk of an attack.
• Enable a checker in the assembly process. If it detects large bits of data, it will stop the abnormal packets and prevent crashing.

How to block Ping requests using iptables?

To block ping requests coming to and from your server using iptables, follow these instructions:

First, to reject incoming ping requests, execute the following command:

$ sudo iptables -A INPUT -p icmp –icmp-type echo-request -j REJECT

This will lead to an error message being displayed for each blocked ping. If you prefer to silently drop these requests without generating error messages, use the following commands instead:

$ sudo iptables -A INPUT -p icmp –icmp-type echo-request -j DROP

$ sudo iptables -A OUTPUT -p icmp –icmp-type echo-reply -j DROP

The first command silently blocks incoming ping requests, while the second one prevents sending out ping replies from your server.

Implementing network protocols against PoD attack

In the previous section, we examined the most popular ways to safeguard against Ping of Death attacks. Now, let’s delve into how network protocol-level measures can further fortify your defenses:

• Deep Packet Inspection (DPI): This technique goes beyond basic header analysis to examine the actual data content of packets. DPI can identify, categorize, and block packets that exhibit patterns typical of PoD attacks, such as unusual fragmentation or payload anomalies.
• Intrusion Detection Systems (IDS): IDS can be configured to recognize signatures or patterns of PoD attacks. By monitoring network traffic in real-time, IDS can alert administrators and automatically take action against suspicious packets.
• Protocol Anomaly Detection: This method involves analyzing the behavior of protocols like ICMP, TCP, and UDP against established norms. Any deviation from these norms, such as fragmented ICMP packets that could signal a PoD attack, can be flagged for further inspection or blocked.

Suggested article: Full Guide on TCP Monitoring vs. UDP Monitoring

• Stateful Packet Inspection (SPI): Unlike stateless firewalls that only examine packet headers, SPI firewalls track the state of active connections and make decisions based on the context of the traffic. This approach can effectively block malformed packets characteristic of PoD attacks.

Conclusion

You may think that Ping of Death is outdated and it does not have a chance in modern networks. The truth is that this threat should not be neglected. It may find its way and crash your system. Therefore, it is best to take all of the precious measures in order to prevent and stop such malicious attacks.

The post Ping of Death (PoD) – What is it, and how does it work?  appeared first on ClouDNS Blog.

However, like every other IT problem, DNS issues can be resolved. You just have to know the right tools and commands. In this blog post, we’ll delve into some of these essential DNS troubleshooting tools and commands that every network administrator ought to arm themselves with.

Common DNS Issues 

Before we dive into the tools and commands, let’s understand the most common DNS issues that most administrators often encounter:

1. DNS Downtime: This occurs when DNS servers that translate domain names are temporarily unavailable.
2. Incorrect DNS Configuration: This involves errors in the setup of DNS settings which may lead to problems accessing certain websites or the internet.
3. DNS Cache Poisoning: Also known as DNS Spoofing, it refers to fraudulent entries in the DNS cache, causing traffic to be directed to the wrong place.
4. DNS Propagation Delays: This happens when you make changes to your DNS records and they are not immediately effective due to the time taken to update network servers around the globe.

Now that we have a basic understanding of common DNS issues, let’s explore the essential DNS troubleshooting commands that can help you diagnose and resolve these problems.

DNS Troubleshooting Tools

There are plenty of tools that you can use. The tools can be specific for Linux, Windows, or Mac OS, or they can be browser-based. Most of the tools that we will show you overlaps in functionality, and it will be your decision which one you would use in the future.

Check if the problem is not just in your device

Before you start with the DNS troubleshooting, check if the problem is only local. If you are trying to access your website, but you are getting this message “DNS_PROBE_FINISHED_NXDOMAIN” the problem might be in your device. We recently wrote a way to fix it. Go and read the article. 

Dig command

The ‘dig’ command, which stands for ‘Domain Information Groper,’ is a handy command-line tool used in the DNS name resolution process. It sends a DNS query to a specified DNS server and gets a response. It’s a useful tool for finding DNS-related issues. 

With this command you can see all the DNS records. You can use it on Linux and Mac OS, but you can search for a port for Windows too. A typical dig command will show you an Authority Section. You can see if the DNS is pointing correctly.

Use it with +trace in dig +trace combination “dig +trace YOURDOMAIN” to see the whole route of your query. This way you can locate the exact problem.

ClouDNS Free DNS tool

ClouDNS brings to you a valuable Free DNS tool that has transformative capabilities to enhance your DNS troubleshooting tactics. With this tool, you can inspect the DNS records for a specific host and assess the speed of DNS queries. Aside from these, you can also create a comprehensive audit, a feature that helps in in-depth analysis and identification of problematic areas.

Designed to facilitate the work of their customers, the ClouDNS Free DNS tool is user-friendly and accessible, making DNS troubleshooting a breeze even for beginners in the field. All you need to do is enter your domain and host into the tool, select the tool type as “DNS Records”, and choose ‘Google’ as your DNS resolver, then hit ‘CHECK’. 

What’s more, this powerhouse tool is free of cost, making it a stellar choice for efficient network management. The value it provides, particularly in terms of insight into DNS records and query speed, can go a long way in troubleshooting DNS-related problems swiftly and effectively.

Traceroute

The ‘traceroute’ command enables you to track the pathway that a packet takes from the host to the destination server. As the name suggests, this will be ideal for checking the entire route of a DNS query. You can use it on Windows as Tracert, Linux and Mac OS as traceroute. You can try it with a domain or IP address, and you will see a result with all the hops and response time.

NSLookup

‘NSLookup‘ stands for ‘Name Server Lookup’. This command-line tool is used for obtaining information about DNS settings. It allows users to enter a host name and find out the corresponding IP address, or vice versa.

This command lets you check any type of DNS record. You can use it to see all the available DNS records, or you can look for a specific type like – A, AAAA, SOA, MX, PTR, NS, etc. You can use it to troubleshoot a domain using a particular port too. 

Host command

‘Host’ command is very similar to the NSLookup but available only on Linux. You have to write the commands in the Terminal, and you can see the different types of DNS records.

One thing that you can troubleshoot if you have problems with your emails are the TXT records. You can see if there is a SPF record. It is a TXT record that prevents spoofing and stops your outgoing emails from going directly into the spam folder.

Generate SPF record for free!

Conclusion

There are plenty of useful tools that you can use for DNS troubleshooting. Try all of these and find the right one for you and your problem. Many overlaps in functionality, but have some small differences that can help you in a specific case.

As you saw, there are utilities for every operating system so that you can find the problem easily. After you see where the problem is, it is easy to fix it.  

The post DNS Troubleshooting – tools and commands appeared first on ClouDNS Blog.