Suggest an editImprove this articleRefine the answer for “What is Port Security?”. Your changes go to moderation before they’re published.Approval requiredContentWhat you’re changing🇺🇸EN🇺🇦UAPreviewTitle (EN)Short answer (EN)**Port Security** is a network security mechanism on switches that controls which devices can connect to a specific physical port. **Key point:** Port Security is part of a multi-layered defense, not the only security measure, since a MAC address can be spoofed.Shown above the full answer for quick recall.Answer (EN)Image**Port Security** is a network security mechanism on **switches** that **controls which devices can connect to a specific physical port**. In simple terms: *Port Security decides which devices are "allowed" on each switch port.* --- ## Why Port Security is needed Without Port Security: - **any device** can be connected to a free port; - an attacker can gain access to the internal network; - attacks from the local network become possible. Port Security allows you to: - limit the number of devices on a port; - allow connections only from **known MAC addresses**; - prevent unauthorized access. --- ## How Port Security works The switch checks the **MAC addresses of devices** connecting to a port and applies rules: - if the MAC address is allowed, access is granted; - if it is not allowed, the port is blocked or the traffic is dropped. It is usually used **at the access layer**. --- ## Main features of Port Security ### 1. Limiting the number of MAC addresses For example: - only **1 device** can be connected to a port; - if a second one appears, protection is triggered. --- ### 2. Recording allowed MAC addresses MAC addresses can be: - **static** (set manually); - **dynamic** (learned automatically); - **sticky** (learned and saved). Sticky MAC is the most popular option. --- ### 3. Reaction to a violation (violation mode) If the rules are violated, the port can: - **Protect**, which simply blocks the traffic; - **Restrict**, which blocks it and logs the event; - **Shutdown**, which fully disables the port (the strictest option). --- ## Which attacks Port Security prevents - connecting someone else's laptop to the network; - MAC flooding; - unauthorized access to the local network. This is protection **at the data link layer (L2)**. --- ## Limitations of Port Security It is important to understand: - a MAC address can be spoofed; - it does not protect against attacks above L2; - it requires administration. That is why Port Security is **part of a multi-layered defense**, not the only security measure. --- ## A simple example Port Security is like: > an outlet with an access list: > power is supplied only to the devices that are on the list.For the reviewerNote to the moderator (optional)Visible only to the moderator. Helps review go faster.