How to fully Block DoS attacks through layer-3 Switching

Source: Internet
Author: User

Layer-3 switches are quite common, So I studied how layer-3 switches fully Block DoS attacks. Here I will share with you, hoping to help you. Although global network security experts are developing methods to defend against DoS attacks, DoS attacks are ineffective because they exploit the weakness of TCP protocol. Configure a layer-3 Switch and install a dedicated DoS identification and prevention tool to minimize the loss caused by DoS attacks.

Using a layer-3 Switch to establish a comprehensive network security system, it must be based on a layer-3 Switch and an intelligent network with routing as the core, with a sound security policy management tool above layer-3. At the same time, the network design stage should be reasonably arranged.

Lan Layer

On the LAN layer, network administrators can take many preventive measures. For example, although it is almost impossible to completely eliminate the counterfeiting of IP groups, the network administrator can build a filter. If the data carries the source address of the Intranet, it can effectively reduce internal counterfeit IP attacks by limiting the data input traffic. Filters can also restrict external IP group streams to prevent DoS attacks from fake IP addresses from being used as an intermediate system. Other methods are as follows: Disable or restrict specific services. For example, limit UDP services to be used only for Network diagnosis purposes on the Intranet.

Unfortunately, these restrictions may negatively impact legal applications (such as using UDP as the RealAudio transmission mechanism. If attackers can force victims not to use IP services or other legitimate applications, these hackers have achieved DoS attacks.

Network Transmission Layer

The following section describes the limitations of the network transport layer.

1. layer-independent line rate service quality (QoS) and Access Control

The emergence of a line-rate layer-3 Switch with configurable smart software, layer-independent QoS, and access control functions improves the capability of network transmission devices to protect data flow integrity. In traditional routers, authentication mechanisms (such as filtering out fake groups with internal addresses) require traffic to reach the vro edge and comply with the standards in the specific access control list. However, maintaining the access control list is not only time-consuming, but also greatly increases the router overhead. In contrast, the line rate multi-layer switch can flexibly implement various policy-based access control.

This layer-independent access control capability completely separates security decisions from network structure decisions, so that network administrators do not have to adopt sub-optimal routing or Switching Topology while effectively deploying DoS prevention measures. As a result, network administrators and service providers can seamlessly integrate policy-based control standards in the entire metropolitan area network, data center, or enterprise network environment, regardless of the complex router-based core services, or a relatively simple second-level exchange. In addition, data authentication for line rate processing can be performed in the background without performance latency.

2. Customizable filtering and "trusted neighbor" mechanisms

Another advantage of smart multi-layer access control is that it can easily implement custom filtering operations, such as customizing the control granularity of system response according to specific standards. Multi-layer switching can push groups to specific QoS configuration files with the specified maximum bandwidth limit, rather than making simple "pass" or "discard" decisions for groups that may be DoS attacks. This method can prevent DoS attacks and reduce the risk of dropping valid data packets. Another advantage is the ability to customize routing access policies and support the "trusted neighbor" relationship between specific systems to prevent unauthorized use of internal routes.

Taking the ExtremeWare package of gejin network as an example, it maps and covers IEEE 802.1p and DiffServ tags, enables all layer-3 switches to ignore, observe, or process any DiffServ Mark sent from "untrusted neighbors. These mechanisms enable the system administrator to adjust internal routing policies based on traffic from specific neighbors.

3. Custom network login configuration

Network login uses a unique user name and password to authenticate the identity before the user is authorized to enter. In network login, the user's browser submits the Dynamic Host Configuration Protocol (DHCP) to the switch, the switch captures the user identity, sends a request to the RADIUS server for identity authentication, only after authentication, A layer-3 switch allows the group traffic sent by the user to flow through the network. The draft IEEE 802.1 stipulates that the network login mechanism can control users' access to layer-3 switches, minimizing the risk of direct DoS attacks. Network logon also provides a robust mechanism for managing and tracking internal users.

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