Meet Wallarm team at Gartner 2024!
Meet Wallarm team at Gartner 2024!
Meet Wallarm team at Gartner 2024!
Meet Wallarm team at Gartner 2024!
Meet Wallarm team at Gartner 2024!
Meet Wallarm team at Gartner 2024!
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User Datagram Protocol

The User Datagram Protocol is identical to the "Ugly Duckling" in the story of Hans Christian Andersen. This unassuming protocol gained surprising popularity as the conveyance for the flashy original hypermedia programs made feasible by internet speeds after being ignored and mocked for decades. It has replaced Transmission Control Protocol as the go-to blueprint for packages that involve rapid info distribution.

User Datagram Protocol

An Overview of UDP Protocol

The Internet Protocol (IP) serves as the foundation for the UDP payload broadcast over a grid. It eliminates the need for a pre-transmission multilateral handshake between the distribution and receiving hosts. In addition, an end-to-end link is unnecessary.

It is well-suited for real-time or high-performance applications that don't want info authentication or rectification since it eliminates the overhead related to networks, fault checks, and retransmission of misplaced data. Application-level verification can be carried out if necessary.

Remote procedure call (RPC) applications often employ UDP, while RPC can also be built atop TCP. In order to ensure their own consistency, RPC apps must be mindful that they are using the user datagram protocol definition.

How Does UDP Work?

It is a deep-rooted blueprint for messages that transmits statistics between networked systems. In contrast to TCP, UDP streamlines data transport by delivering packets (technically, payloads) to their terminus without first setting up an indirect association. It neither specifies the dispatch order of its payloads nor confirms their influx.

It has checksums to make sure the info is intact and port numbers to specify what the stats are for. A 'handshake' amongst the transmitter and the recipient is not required before info allocation may begin.

Since the receiver may get garbled, faulty, or missing data while using UDP, it is not recommended for transmitting sensitive information. Primarily, it is utilized in situations when timely info distribution is more important than error-free communication.

UDP Header Structure

The header that UDP uses to encapsulate payloads comprises quatern fields and octonary bytes in total.

The parts of a UDP header are as follows:

  • Origin port

The terminal of the transmitting device. This subject can be adjusted to zero if the PC at the terminus is not obligated to counter to the dispatcher.

  • Destination port

the interface of the gadget that will receive the facts. UDP port numbers array from 0 to 65535.

  • Length

Indicates the number of bytes that make up the UDP preamble and UDP payload data. The underlying IP guidelines utilized to mediate info determines the supreme duration of the UDP extent field.

  • Checksum

It enables the receiving gadget to authenticate the header and payload of the packet. In IPv4 it is voluntary, but in IPv6 it is compulsory.

How Does UDP Work

Applications of UDP

With an understanding of its inner workings in hand, let's examine its implications.

Games, Voice, And Video

Network applications like gaming, voice and clip communications, and so on all benefit greatly from UDP because of its low latency. Data loss won't be noticeable in these cases due to the nature of the examples being used. It is used to transmit data without loss, but in some circumstances forward error correction techniques are employed in conjunction with UDP to enhance audio and video quality.

Multicast And Routing Update Protocols

Because of its packet-switching capabilities, UDP is well-suited for use in multicast scenarios. UDP is used by 'one-to-many' applications to send data to several receivers in parallel without first establishing individual point-to-point connections. Each datagram is replicated and delivered to a single multicast address in these situations. This replicated version is sent to all of the receivers. This configuration is helpful for providing notices, evaluating the state of a system, and transmitting video and audio to numerous receivers (as in distance learning).

Lossless Data Transfer

It can be used for tasks that demand absolutely secure info transfer. A package designed to handle the retransmission of dropped packets and proper sorting of incoming packets might use UDP. This method has the potential to increase the speed at which huge files are sent via TCP.

UDP resides in Layer 4 (Transport) of the Open Systems Interconnection (OSI) communication paradigm. Trivial File Transfer Protocol (TFTP), Real Time Streaming Protocol (RTSP), and Simple Network Management Protocol (SNMP) are just a few of the higher-level protocols that UDP interacts with to handle data transmission capabilities.

Fast Applications

It is suitable for use where speed is more significant than reliability. If you're delivering data from a quick acquisition and a few drops in the transmission are acceptable, it could be the way to go.

Services That Do Not Require Fixed Packet Transmission

Apps that need dependable data transfer can use UDP, even though these programs should have their own means of responding to UDP packets. These services are helpful since they do not rely on predetermined patterns to ensure the cohesion of each data packet. Users have control over how and when they react to incorrect or disorganized facts.


They typically use TCP for data transfer, although some services give users the option of using UDP instead. This is due to the fact that VPNs have become especially popular for broadcasting high-definition videos, which necessitates resolving issues with TCP's latency.

Domain Name System Search

Entering a URL into a web browser prompts a search for the domain's corresponding IP address, after which a GET request can be sent to the server. Subscribers are more likely to abandon the service if this procedure takes more than a few milliseconds. It is used by the Domain Name System (DNS) interface so that customers can swiftly retrieve websites.

Disadvantages Of the Protocol

UDP's absence of facts authentication and network restrictions can lead to transmission problems. Among these are:

  • There is no promise that packets will arrive in any certain order.
  • There was no attempt to ensure that the receiving computer was prepared to receive the message.
  • We have no safeguards against packets being sent again.
  • There is no assurance that the terminus will receive all of the data sent. In contrast, UDP has a checksum feature for ensuring the integrity of each transmitted packet.

Difference Between UDP And TCP

The Transmission Control Protocol (TCP) and the User Datagram Protocol (UDP) are two of the many protocols in the IP suite.

Because of its superiority over competing protocols in areas like packet fragmentation, packet delivery reliability, and packet reassembly, TCP has become the de facto standard for most internet connections. However, the increased data overhead and latency introduced by these services are not free.

When compared to TCP, which necessitates the establishment of a virtual circuit before any info transfer can occur, UDP is said to be a connectionless protocol. The packet-based nature of the underlying communication protocol results in significantly reduced bandwidth overhead and delay. UDP allows packets to potentially take several routes between the sender and the receiver. This can lead to packets being released or received out of sequence.

UDP features include the following:

  • This protocol does not require any sort of link between its participants.
  • Uses include voice-over IP (VoIP), clip streaming, online betting, and live broadcasting.
  • It's more efficient and uses less energy.
  • The packets may not arrive sequentially.
  • It permits packets to be lost without the sender being aware of the fact.
  • Games, for example, that rely on quick and efficient data transfer would benefit more from its use.

The following are some of the features of TCP:

  • Comparability is the focus of this protocol.
  • In terms of Internet usage, it is by far the most popular protocol.
  • It ensures that every data sent is received by its intended receiver and that no data packets are lost in transit.
  • It sends info in a sequential fashion so that it can be reassembled without any problems.
  • It's less efficient and uses more energy.
  • It uses a more substantial preamble than UDP.
  • It works best for less time-sensitive applications that require strong dependability.

Using The UDP Protocol in DDoS Attacks

It is susceptible to numerous DDoS assaults because of its lack of a verification mechanism and end-to-end connectivity. Attackers can use this vulnerability to gain direct access to the application by forging packets with arbitrary IP addresses.

This is dissimilar from TCP, where the sender needs to get packets back from the receiver before transmission can start.

DDoS outbreaks that focus on UDP include:

  1. UDP Flood

With the knowledge that there is no way to authenticate the genuine source of the packets, a UDP flood entails sending massive numbers of faked UDP packets to various ports on a single server. The server becomes overloaded, and it responds to all the requests by sending ICMP 'Destination Unreachable' responses.

DDoS attackers frequently use generic network layer attacks, in which they send out large numbers of spoofed UDP packets to overload a target network. Only by dynamically increasing the capacity of a network in response to a DDoS attack can it be protected.

  1. DNS Amplification

The invader in a DNS intensification attack sends UDP packets to the victim's DNS resolvers using a faked IP report that corresponds to the victim's IP. In response, DNS servers will relay the victim's response. The attack is designed in such a way that the DNS response is significantly larger than the first request.

Overwhelming the targeted system might occur when several customers use various DNS resolvers. Amplification can increase the throughput of a 27Gbps DDoS assault to 300Gbps.

  1. UDP Port Scan

In order to discover which ports on a server are accessible, attackers send UDP packets to those ports. The Port is closed if the server sends ICMP 'Destination Unreachable' response. In the absence of such a response, the attacker can safely assume that the port is open and proceed with his or her attack.

UDP Pseudo Header

  • The UDP packet's destination can be confirmed with the help of a pseudo-header.
  • The proper target is a combination of a machine name and a protocol port number on that system.

UDP Pseudo Header Details

  • Only the protocol port number is included in the UDP header. Thus, a checksum is computed on the transmitting machine that includes the destination IP address and the UDP packet to ensure that the packet was sent to the right place.
  • UDP software at the receiving end validates the checksum by accessing the terminus IP address from the IP packet's header.
  • If the checksums match, the packet has successfully arrived at both the destination host and the correct protocol port on that host.

UDP Best Practices

Businesses need to study the best practices for using a user datagram protocol before putting it into reality with a software app. Design specifications for providing services through unicast UDP can be found in documents like the UDP Usage Requirements.

Account For Path Conditions and Transport

It needs to make use of full-featured transport like TCP and be resilient to a wide variety of internet path conditions.

Bandwidth, transmission delays, reordering probabilities, congestion levels, loss rates, and supported message sizes might vary greatly along different internet paths. Even along the same road in cyberspace, things may change over time. As a result, apps should be built so that they don't presume anything about the nature of a given route.

Instead, they should make use of methods that ensure the secure execution of packages under a wide range of path conditions. You can do this by meticulously investigating the path your communications are now taking across the internet. Adhering to this procedure aids in establishing a transmission behavior that is both long-lasting and equitable for another gridlock along the same route.

Implement Congestion Control

UDP setups should control transmission rate and traffic congestion. In an application or protocol without congestion management, UDP datagrams must be delivered to the target host at a controlled rate.

Packages should control all UDP traffic sent to a destination. Systems that fork many worker processes or use multiple sockets for datagram creation should regulate traffic congestion.

Bolster Bulk Transfer Applications

UDP bulk transfers should use TCP-friendly rate control (TFRC) or other bandwidth-leveraging methods.

Applications that exchange several UDP datagrams per round trip time (RTT) using UDP should use TFRC, window-based congestion control like TCP, or another congestion control-compliant software.

TFRC's congestion control and fairness are IETF-compliant. Instead of TFRC or TCP-like windowing, a congestion management strategy that uses bandwidth fairly with TCP should be considered for bulk-transfer applications.

Monitor packet loss to keep it below acceptable limits. Suppose a TCP flow on the same network path under identical conditions has an average throughput that is not greater than the UDP flow when estimated utilizing a sensible timescale. In that case, the acceptable packet loss criterion is met.

Finally, a bulk-transfer application without congestion management can transmit using reserved path capacity. This is safe only in constrained networking situations. If UDP traffic from such an application enters an unprovisioned network path, it could degrade other traffic and cause congestion collapse.

Streamline Low Data Volume Applications

Non-bulk UDP setups should measure RTT and send 1 datagram/RTT. Transfer a maximum of one datagram every three seconds and back-off retransmission timers after loss.

TFRC or a similar overcrowding control strategy for an application that exchanges a few UDP datagrams with a terminus has limited network benefits. Those techniques' congestion control functions only for longer transmissions.

But apps that only send a small number of datagrams should control how they send datagrams and keep the average number sent per RTT to less than one. For any destination, estimate the RTT.

Secure Overall Network

Implementing UDP requires network security measures, such as firewalls, intrusion detection and prevention systems, network access control, and spam filters. Firewalls provide basic network defense by isolating networks, while IDS spots intruders and prompts security teams. IPS combines IDS and firewall capabilities to thwart intrusions but can lead to high IT costs. NAC ensures only compliant endpoints access network resources. Spam filters prevent unwanted emails based on pattern analysis and vendor policies.

Wallarm Will Help Protect Against UDP Attacks

When it comes to protecting your whole API and web application portfolio in multi-cloud and cloud-native settings from the aforementioned assaults, Wallarm is the only solution that combines best-in-class API Security Platform and WAAP (Next-Gen WAF) capabilities. It can assist you in mitigating the above-described attacks as follows:

  • Volume Based Assaults

Wallarm prevents UDP floods and DNS amplification assaults by ingesting and screening out bad traffic through our worldwide network of scrubbing centers—cloud-based clusters that scale on demand to counter DDoS attacks. While fraudulent requests are rejected by the scrubbing center, legitimate user traffic is allowed through.

  • Protocol Attacks

Wallarm can stop "harmful" traffic, such as UDP traffic aiming at non-existent ports before it reaches your site. Wallarm also offers visitor identification technology, which can tell the difference between a human, search engine, and automated customers, as well as hostile ones.


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February 26, 2024
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