Mar
23
2020
How to configure PassiveID in Cisco ISE
How-to-configure-PassiveID-in-Cisco-ISE-1

Starting from ISE 2.2, PassiveID is a feature to gather user-to-IP mapping information with or without having 802.1X deployed. PassiveID gathers information from the Microsoft Active Directory environment using the Microsoft Windows Management Interface or the Active Directory agent, or through a switched port analyzer (SPAN) port on a switch. It can also gather authentication information through syslogs, a Citrix terminal server agent, and a custom API. The configuration is very easy and requires just a few clicks of a mouse.

Mar
15
2020
802.1x: Introduction and general principles
802.1x-Introduction-and-general-principles-mini

IEEE 802.1X is an IEEE Standard for port-based Network Access Control to prevent unauthorized devices from gaining access to the network. It defines the encapsulation of the Extensible Authentication Protocol (EAP) over IEEE 802, known as “EAP over LAN” or EAPOL. 802.1X authentication involves three parties: a supplicant, an authenticator, and an authentication server.

Dec
16
2019
How to set up raid on Cisco ISE appliance
How-to-set-up-raid-on-Cisco-ISE-appliance-1

Recently, I have installed an ISE 2.6 cluster based by two SNS3615 appliances. After some months, the customer asked me to redundant each hard disk with RAID1. To accomplish this request, it is mandatory access to the CIMC interface (if you don’t know what is CIMC read this article). First of all, check that the appliance is power up, then go to “Storage -> Cisco 12G Modular Raid Controller with 2GB cache”:

Jun
26
2019
BGP route leak sends European traffic via China
BGP-route-leak-sends-European-traffic-via-China

On Thursday June 6, 2019, traffic destined to some of Europe’s biggest mobile providers was misdirected in a roundabout path through the Chinese-government-controlled China Telecom, in some cases for more than two hours. “Swiss data center colocation company AS21217 leaked over 70,000 routes to China Telecom (AS4134) in Frankfurt, Germany. China Telecom then announced these routes on to the global internet redirecting large amounts of internet traffic destined for some of the largest European mobile networks through China Telecom’s network. Impacts were seen by some of Europe’s largest networks in Switzerland, Holland, and France among other countries.” said Doug Madory, […]

Jun
12
2019
StackWise Virtual on Catalyst 9500
StackWise-Virtual-configuration

During the Cisco Live 2016 in Las Vegas, Cisco presented the new feature named “StackWise virtual” supported by the IOS XE Denali in the 3850 switch series and later, in the new Cisco Catalyst 9500 family. Similarly to the old Virtual Switching System (VSS), the stackwise virtual allows the clustering of two chassis together into a single, logical entity, to allow high availability, scalability, management and maintenance.

May
6
2019
Critical SSH flaw affects Nexus 9000
Cisco-vulnerabilities

The first of May, Cisco has revealed that its Nexus 9000 fabric switches have a critical flaw that could allow anyone to remotely connect to a vulnerable device using Secure Shell (SSH) and control it with root user privileges. Discovered and reported by Oliver Matula of ERNW Enno Rey Netzwerke in cooperation with ERNW Research, the issue is the presence of a default SSH key pair in all devices could be exploited by an attacker by opening an SSH connection via IPv6 to a targeted device (IPv4 is not vulnerable). Tracked as CVE-2019-1804 and featuring a CVSS score of 9.8, […]

Oct
9
2018
Troubleshoot a DMVPN phase 3 architecture
DMVPN-Phase3-in-depth

In the last article, I explained how to configure DMVPN phase3, but what are the most useful commands to troubleshoot this type of network architecture? Five are the main group of commands used to troubleshoot a DMVPN topology: show dmvpn […] show ip nhrp […] show ip eigrp […] show crypto […] The “show dmvpn” and “show ip nhrp” commands permit to obtain the state of the tunnels. On hub router, all tunnels are dynamic (D attribute) because it waits the registration from spokes routers (“ip nhrp map multicast dynamic”).

Jul
16
2018
DMVPN Phase 3: a complete guide
DMVPN-Phase3-in-depth

In a previous article, I explained what is and how it works DMVPN technology. In this article you see how to configure DMVPN phase3. This phase allows spokes to build a spoke-to-spoke tunnel and to overcomes the phase2 restriction using NHRP traffic indication messages from the hub to signal to the spokes that a better path exists to reach the target network. The phase3 configuration is based by 4 steps: Define Tunnel interface (mandatory) Define NHRP (mandatory) Define EIGRP Process (mandatory) Define IPSEC Profile (optional) In this example, there are 3 routers: one hub (Ciscozine) and two spokes.

Jun
26
2018
Understanding Cisco DMVPN
Understanding-DMVPN-Phase-2

In an old post, dated 2011, I explained various types of VPN technologies. In seven years several things have changed: SHA1 is deprecated, des and 3des are no more used for security issues, but some VPN technologies are still used with protocols more secure (SHA256, AES, …). In this article, I explain how DMVPN works and what are the key components of it. Cisco DMVPN uses a centralized architecture to provide easier implementation and management for deployments that require granular access controls for diverse user communities, including mobile workers, telecommuters, and extranet users.

Apr
5
2018
Cisco Smart Install Remote Code Execution
Cisco-Smart-Install-Remote-Code-Execution

At the end of March, Cisco published a stack-based buffer overflow vulnerability in Smart Install Client code. This vulnerability enables an attacker to remotely execute arbitrary code without authentication. So it allows getting full control over a vulnerable network equipment. Cisco Smart Install is a “plug-and-play” configuration and image-management feature that provides zero-touch deployment for new (typically access layer) switches. The feature allows a customer to ship a Cisco switch to any location, install it in the network, and power it on without additional configuration requirements. The Smart Install feature incorporates no authentication by design.

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