Network Attacks: Techniques, Tools, and Detection

Part of the Cybersecurity Skills Guide — This article is one deep-dive in our complete guide series.

By HADESS Team | February 28, 2026 | Updated: February 28, 2026 | 5 min read

Understanding network attacks from the attacker’s perspective is necessary for building effective defenses. If you do not know how ARP spoofing, DNS poisoning, or VLAN hopping works at a protocol level, you cannot write detection rules or design networks that resist these techniques.

ARP Spoofing

ARP is a trusting protocol — it has no authentication mechanism. Any device on a broadcast domain can send gratuitous ARP replies claiming to own any IP address. ARP spoofing sends forged ARP replies to associate the attacker’s MAC address with the gateway’s IP address (or any other target), causing traffic to flow through the attacker’s machine.

Tools like Ettercap and arpspoof automate this. Once positioned as a man-in-the-middle, the attacker can intercept, modify, or capture all traffic between the victim and the gateway.

Detection: monitor for ARP replies that were not preceded by ARP requests. Look for multiple IP addresses resolving to the same MAC address. Deploy Dynamic ARP Inspection (DAI) on your switches — it validates ARP packets against the DHCP snooping binding table and drops spoofed replies.

Prevention: use static ARP entries for critical infrastructure, enable 802.1X port authentication, and segment networks to reduce broadcast domain size.

DNS Poisoning

DNS cache poisoning injects false DNS records into a resolver’s cache, redirecting queries for legitimate domains to attacker-controlled IPs. The classic Kaminsky attack sends flood of spoofed DNS responses, trying to match the transaction ID of an outstanding query.

On the local network, an attacker who has achieved MITM positioning can intercept DNS queries and respond with forged answers before the legitimate resolver. LLMNR and NBT-NS poisoning on Windows networks (automated by Responder) exploit fallback name resolution protocols when DNS fails.

Detection: monitor for DNS responses that do not match outstanding queries. Look for unusually short TTLs on DNS records that normally have long TTLs. Alert on internal systems receiving DNS responses from unexpected sources.

Prevention: deploy DNSSEC where possible. Disable LLMNR and NBT-NS via Group Policy. Use DNS-over-HTTPS or DNS-over-TLS for resolver communication. Configure source port randomization on recursive resolvers.

Man-in-the-Middle Attacks

MITM attacks position the attacker between two communicating parties. ARP spoofing and DNS poisoning are means to achieve MITM positioning. Once positioned, the attacker can:

• Capture credentials transmitted over unencrypted protocols
• Strip TLS from HTTPS connections (SSL stripping) by intercepting the initial HTTP redirect
• Inject content into unencrypted HTTP responses
• Relay authentication challenges in protocols like NTLM (NTLM relay attacks)

Tools like mitmproxy provide interactive interception of HTTP/HTTPS traffic. Bettercap combines ARP spoofing, DNS spoofing, and SSL stripping into a single framework.

Detection: HSTS (HTTP Strict Transport Security) prevents SSL stripping for domains the browser has previously visited. Certificate pinning detects unauthorized certificates. Network monitoring for unexpected ARP or DNS changes catches the positioning phase.

VLAN Hopping

VLANs provide network segmentation, but misconfigurations allow attackers to send traffic across VLAN boundaries:

Switch spoofing: if a switch port is configured to auto-negotiate trunking (DTP), an attacker can configure their interface as a trunk port and gain access to all VLANs on that trunk.

Double tagging: the attacker sends frames with two 802.1Q tags. The first switch strips the outer tag and forwards based on the inner tag, delivering the frame to a VLAN the attacker should not reach. This only works in one direction and requires the attacker to be on the native VLAN.

Prevention: disable DTP on all access ports (switchport nonegotiate). Set all access ports to a specific VLAN. Change the native VLAN to an unused VLAN ID. Explicitly configure trunk ports and limit allowed VLANs.

Next Steps

• Test your network security knowledge with the skills assessment
• Explore network defense and monitoring topics in the skills library
• Plan your career path with the certificate roadmap — CEH, PNPT, and OSCP cover network attack techniques

Related Guides in This Series

• EDR: Endpoint Detection, Response, and Threat Hunting — HADESS | 2026
• Firewall Management: Rules, Zones, and Change Control — HADESS | 2026
• Hardware Security Modules: Key Management and Compliance — HADESS | 2026

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HADESS Team consists of cybersecurity practitioners, hiring managers, and career strategists who have collectively spent 50+ years in the field.