Access-Lists - Anything Over IP

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Access-Lists

A collection of 11 posts

Static NAT overloaded???

Static NAT overloaded???

Static NAT is a one-to-one mapping between a local address and a global address. But, what if you have 2 local addresses that map to the same global address? Well, you would have an overloaded static NAT, which doesn't make much sense because the router wouldn't

Configuring PAT on Cisco Routers (NAT Overload)

Configuring PAT on Cisco Routers (NAT Overload)

What is PAT (Port Address Translation)? PAT (Port Address Translation), also known as NAT Overload, is a form of Network Address Translation that allows multiple devices on a private network to share a single public IP address. Unlike one-to-one NAT, PAT uses port numbers to differentiate between multiple internal connections,

Configuring Dynamic NAT on Cisco Routers

Configuring Dynamic NAT on Cisco Routers

Welcome to another tutorial on Network Address Translation (NAT). In this post we'll be looking at how to configure Dynamic NAT on Cisco routers. I highly recommend that you first read through my previous post on configuring static NAT before continuing with this one. What is Dynamic NAT?

Configuring Basic ISDN with Interesting Traffic

Configuring Basic ISDN with Interesting Traffic

When configuring ISDN with interesting traffic, it’s important to first understand how Cisco defines ‘interesting’ and what this means in terms of the connection been formed. Interesting traffic is traffic that we define in the form of an access-list that is allowed to cause the ISDN to dial. This

DoS TCP SYN Attack Mitigation

DoS TCP SYN Attack Mitigation

A DoS (Denial of Service) attack is an attempt to make a machine or network resource unavailable to its intended users. One common type of DoS attack is the TCP SYN flood attack, which exploits the TCP three-way handshake process. Understanding TCP SYN Flood Attacks In a normal TCP connection

Mitigating SubSeven attacks

Mitigating SubSeven attacks

SubSeven – aka: Sub7 and Sub7Server is a backdoor program, in the form of a Trojan, used mostly for causing trouble on computer networks. It can be used for simple attacks such as hiding the mouse cursor and opening applications, but it can also be used for more serious attacks including

Mitigating Smurf DoS Attacks

Mitigating Smurf DoS Attacks

A smurf attack is a form of denial of service (DoS) attack that takes advantage of IP broadcasting and ICMP ping requests to overwhelm a target host with traffic. The attack works by sending ICMP echo requests (ping packets) to a network's broadcast address, with the source IP

IP Address Spoofing Mitigation with Access Control Lists (ACL)

IP Address Spoofing Mitigation with Access Control Lists (ACL)

Understanding IP Spoofing IP spoofing is a technique used by attackers to disguise their identity by modifying the source IP address in packet headers. This makes it appear as if the traffic is coming from a trusted source when it's actually originating from a malicious host. Common attack

Restricting access to Telnet and SSH

Restricting access to Telnet and SSH

By default, when you configure Telnet or SSH on a Cisco router or switch, any device that can reach the management IP address can attempt to connect. This poses a security risk, as unauthorized users could potentially gain access to your network equipment. To enhance security, you can restrict which

Cisco Access-lists (ACL's - Access Control Lists)

Cisco Access-lists (ACL's - Access Control Lists)

Access Control Lists (ACLs) are packet filters. They are a list of conditions that categorize packets. They can be helpful for security and for managing traffic flow. For security, ACLs can allow or deny packets to move through the network. For traffic flow management, ACLs can identify traffic that needs

Wildcard Mask

A wildcard mask is used to identify which parts of an IP address to check when applying ACL rules. The wildcard mask works with the IP address of packets that are being evaluated by the ACL, NOT with the IP address in the ACL statement. The wildcard mask uses the