Common Network Attacks Explained

What Is a Network Attack?

A network attack is an unauthorized attempt to breach, disrupt, or intercept a network or its data, targeting the confidentiality, integrity, or availability of network resources. An attack exploits a weakness in a device, protocol, configuration, or user to reach a goal the attacker is not permitted to achieve. The defining traits are:

• Unauthorized intent: the actor lacks permission to access or disrupt the network.
• A target in the CIA triad: always confidentiality, integrity, or availability.
• An exploited weakness: in a device, a protocol, a configuration, or a person.
• A method: ranging from flooding and interception to deception and credential guessing.

Every attack maps to one of those three goals, which is the framing used in the overview of network security. Knowing what an attack tries to break is the first step to choosing the control that stops it.

What Are the Main Types of Network Attacks?

The four families below cover most real-world network attacks, and each has a one-line defense. The sections that follow expand each one with how it works and how to stop it.

What Is a DDoS Attack and How Do You Defend Against It?

A distributed denial-of-service (DDoS) attack floods a target with traffic from many sources to exhaust its resources and block legitimate users, and it is defended by traffic filtering, rate limiting, and upstream mitigation. It targets availability, overwhelming a server or link until it cannot respond. The mechanics and defenses are:

• Distributed sources: traffic comes from many compromised devices at once, usually a botnet, so blocking one address does nothing.
• Resource exhaustion: the flood consumes bandwidth, open connections, or processing until service fails.
• Traffic filtering and scrubbing: a mitigation service absorbs and discards malicious traffic before it reaches the target.
• Rate limiting and redundancy: capping requests per source and spreading load across servers keep a service reachable during a flood.

The scale of these attacks has grown sharply. Cloudflare mitigated 27.8 million DDoS attacks in the first half of 2025 alone, more than in all of 2024, and reported a record 31.4 terabits-per-second attack later that year that lasted only about 35 seconds. Volumes at that level cannot be absorbed by a single firewall, which is why CISA guidance points to upstream mitigation services combined with local rate limiting and redundant capacity.

What Is a Man-in-the-Middle Attack and How Do You Defend Against It?

A man-in-the-middle attack, also called an on-path attack, secretly intercepts traffic between two parties to read or alter it, and it is defended by encryption and authentication. It targets confidentiality and integrity by placing the attacker between sender and receiver. The mechanics and defenses are:

• Interception: the attacker gets onto the path between two parties, often by ARP spoofing on a local network or by a rogue Wi-Fi access point.
• Reading or altering: they can steal data or change it before it reaches the destination, all without either side noticing.
• Encryption: TLS and VPN tunnels make intercepted traffic unreadable without the key, so a captured stream is worthless.
• Authentication: certificate validation verifies the server’s identity, which exposes an impostor sitting in the middle.

Encrypting traffic is the core defense, which is the protection a VPN provides across untrusted networks. The trade-offs between tools that route and protect traffic are covered in the VPN and proxy comparison, and on Wi-Fi the same interception risk is what stronger encryption standards address in WPA2 vs WPA3.

What Is Packet Sniffing and How Do You Defend Against It?

Packet sniffing, also called eavesdropping, passively captures and reads network traffic in transit, and it is defended by encrypting data so captured packets stay unreadable. It targets confidentiality, collecting data that crosses a network the attacker can observe. The mechanics and defenses are:

• Traffic capture: a sniffing tool records every packet passing through a network segment the attacker can reach.
• Data extraction: unencrypted contents such as credentials, cookies, and messages are read straight out of the captured packets.
• Encryption: converting traffic to ciphertext means captured packets reveal nothing useful, the single most effective defense.
• Segmentation: a switched, segmented network limits which traffic an attacker on one point can see.

Encryption defeats classic sniffing because the contents are unreadable, but a newer 2025 threat changes the picture: AI-enhanced sniffers analyze the metadata of encrypted traffic, such as packet sizes and timings, to infer what a user is doing even without reading the payload. That does not break encryption, but it raises the value of segmentation and traffic padding on sensitive links.

What Are Spoofing and DNS Poisoning Attacks?

Spoofing falsifies an address to impersonate a trusted source, and DNS poisoning corrupts domain name records to redirect users to a malicious destination, both defended by authentication and validation. These attacks target integrity, tricking a network or user into trusting false information. The variants and defenses are:

• IP spoofing: forges a source IP to impersonate a trusted device and slip past filtering. Defended by ingress filtering (BCP 38) at the network edge.
• ARP spoofing: sends false address-resolution replies to bind the attacker’s hardware to a victim’s IP, the usual setup for a man-in-the-middle. Defended by dynamic ARP inspection on managed switches.
• DNS spoofing and poisoning: insert false records so a domain name resolves to a malicious server. Defended by DNSSEC, which signs records so a resolver can reject forgeries.
• Validation as the theme: each defense verifies that an address or record is genuine before it is trusted.

Spoofing and DNS poisoning succeed by exploiting trust in unauthenticated addressing, and the fixes come from IETF and NIST guidance: DNSSEC for records, ingress filtering for IPs, and dynamic ARP inspection on the local segment. These deception attacks sit inside the broader set covered in the overview of network security.

What Are Port Scanning and Brute-Force Attacks?

Port scanning probes a network to find open ports and services, and a brute-force attack tries many credential combinations to gain access, both defended by firewalls, monitoring, and account lockouts. Port scanning is reconnaissance; brute force is an access attempt. The mechanics and defenses are:

• Port scanning: sends probes across a range of ports to map which services a target runs, the reconnaissance step that precedes most attacks.
• Brute-force attack: submits many password or key guesses, including credential stuffing with leaked passwords, until one works.
• Firewall filtering: closing unused ports and exposing fewer services shrinks the surface a scan can find.
• Lockout, rate limiting, and MFA: blocking after repeated failures and requiring a second factor make credential guessing impractical.

Scanning maps a target before an attack while brute force tries to walk through the door, and both are blunted by firewalls, monitoring, and lockout policies. A firewall that closes unused ports is the front line here, the function detailed in the analysis of hardware and software firewalls.

Common Network Attacks Comparison Table

How Do You Defend a Network Against Attacks?

A network is defended against attacks by combining encryption, firewalls, segmentation, monitoring, and access control into a layered defense. No single control stops every attack, so a secure network stacks controls that each address different attack types. The core layers are:

• Encryption defeats interception attacks by making captured traffic unreadable.
• Firewalls filter traffic and close the ports that scanning and intrusion target.
• Segmentation limits how far an attacker can spread after a breach.
• Monitoring detects attacks in progress so a response can follow.
• Access control and MFA limit the credentials and permissions that brute force and credential theft rely on.

Layering these controls is the defense-in-depth approach set out in the overview of network security. Continuous observation of traffic for attack signatures is the role of network monitoring, and closing exposed services keeps reconnaissance from turning into a breach.

What Is a Botnet in Network Attacks?

A botnet is a network of compromised devices controlled remotely by an attacker and used to carry out large-scale attacks such as distributed denial-of-service. It turns infected computers, servers, and connected devices into a coordinated tool the operator commands. Its traits are:

• Compromised devices: infected by malware that places them under the attacker’s control without the owner’s knowledge.
• Command and control: lets the operator direct every infected device from a central point.
• Coordinated attacks: the combined devices flood targets, send spam, or spread malware.
• Scale: the combined traffic is what makes a DDoS attack effective. The Aisuru botnet drove several of 2025’s record floods.

A botnet supplies the distributed sources behind a DDoS attack, multiplying the traffic a single device could never produce alone. Defending against botnet recruitment relies on malware protection and access control, while detecting botnet traffic is a job for network monitoring.

Last Thoughts on Common Network Attacks

A network attack is an unauthorized attempt to breach, disrupt, or intercept a network, aimed at the confidentiality, integrity, or availability of its resources. Distributed denial-of-service attacks exhaust availability and now reach tens of terabits per second, man-in-the-middle and packet sniffing attacks target confidentiality, spoofing and DNS poisoning corrupt integrity, and port scanning and brute force probe and guess their way toward access. Each attack has a defense, and the strongest networks layer several rather than trust any one.

Knowing the attacks is only useful next to the defenses that stop them, which is why this connects back to the guide to what a computer network is and the wider set of controls that protect it. From there, encryption, firewalls, segmentation, monitoring, and access control combine into the defense in depth that holds up against the full range of threats.

Key Takeaways:

• A network attack is an unauthorized attempt to breach, disrupt, or intercept a network, and every attack targets one of the three CIA goals.
• A DDoS attack floods a target to exhaust availability; defenses are upstream scrubbing, rate limiting, and redundancy. Records reached 31.4 Tbps in 2025.
• A man-in-the-middle attack intercepts traffic; encryption with certificate validation defeats it.
• Spoofing and DNS poisoning falsify addresses and records; DNSSEC, ingress filtering, and dynamic ARP inspection validate them.
• Port scanning maps a target and brute force guesses credentials; firewalls, lockouts, and MFA blunt both.
• Stolen credentials are the top entry point (22 percent of breaches), so layered defense in depth with MFA matters more than any single control.

Frequently Asked Questions (FAQs)