Reverese Shell on Linux

Reverse shell is technique when a client connects to a server and the client provides its shell to the server. Clients is typically a host hidden behind the NAT or a firewall having an access to the server but not vice versa. Thanks to a reverse shell the server controls a client’s shell having an access […]
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GRE over IPSec Tunnel and NAT Between Cisco and VyOS

The goal of this tutorial is to provide a configuration for Cisco and VyOS network devices with configured PAT (Port Address Translation) that connect two remote sides A and B through point-to-point GRE tunnel encapsulated into a IPsec tunnel. In a previous tutorial we proved that GRE tunnels in conjunction with IPsec tunnels transmit multicast traffic while data […]
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BASH Script for Dictionary Attack Against SSH Server

Although they are several dictionary password attack tools available for Linux such as Hydra, Ncrack, Patator I have decided to practice BASH scripting and write a script getsshpass.sh. The script performs a dictionary attack against SSH server. It reads usernames and passwords from dictionaries (one for username and one for password) and uses them to login to SSH […]
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Collecting MAC and IP Adresses of Hosts Connected to Cisco Switches Using SNMP

The goal of this article is to introduce a script that automates a process of collecting MAC and IP address of hosts connected to Cisco switches using Simple Network Management Protocol (SNMP). We will configure SNMP version 2c and 3 on Cisco switches and create a BASH script that collects required data for us. For this […]
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GRE over IPSec Tunnel Between Cisco and VyOS

The previous tutorial shown GRE tunnel configuration between Cisco router and Linux Core. The big advantage of GRE protocol is that it encapsulates L3 and higher protocols inside the GRE tunnel so routing updates and other multicast traffic can be successfully transferred over the tunnel. The main drawback of GRE protocol is the lack of built-in […]
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Public Key Authentication on Cisco IOS

Have you ever been in that situation that you needed to apply the same configuration quickly on multiple Cisco routers? If yes, you probably wrote a script that connected to routers and sent appropriate IOS commands. The one problem that you certainly had to solved was forcing your script to enter login credentials such as username […]
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MAC address poisoning attack

The goal of this article is making  ARP poisoning attack (Part1) and configure Cisco switch to mitigate ARP poisoning attack (Part2). You can read more theory behind ARP poisoning/spoofing attack on this page: http://su2.info/doc/arpspoof.php Part 1 – ARP poisoning attack on unsecured network infrastructure The picture below shows a testing topology.  Click image to enlarge […]
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MAC address flooding attack in campus network

Theory Hub is a network device which forwards Ethernet received frames to all the ports except the port on which hub previously received frames. This is not very secured method because traffic is send to every port and could be captured by attacker. Unlike hub switch can forward traffic according to destination MAC address in […]
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