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Types of Layer 2/Switch Security Attacks, and Mitigation steps in Brief
Security Attacks against Switches or at Layer 2 can be grouped in four major Categories as follows:
1. MAC layer attacks 2. VLAN attacks 3. Spoofing attacks 4. Attacks on switch devices
1. MAC Layer Attacks Types
MAC address flooding
Description :- Frames with unique, invalid source MAC addresses flood the switch, exhausting content addressable memory (CAM) table space, disallowing new entries from valid hosts. Traffic to valid hosts is subsequently flooded out all ports.
Mitigation Port security. MAC address VLAN access maps.
2. VLAN Attacks
i – VLAN hopping
By altering the VLAN ID on packets encapsulated for trunking, an attacking device can send or receive packets on various VLANs, bypassing Layer 3 security measures. Mitigation Tighten up trunk configurations and the negotiation state of unused ports. Place unused ports in a common VLAN.
ii –Attacks between devices on a common VLAN
Devices might need protection from one another, even though they are on a common VLAN. This is especially true on service-provider segments that support devices from multiple customers.
Mitigation : – Implement private VLANs (PVLAN).
3. Spoofing Attacks
i – DHCP starvation and DHCP spoofing
An attacking device can exhaust the address space available to the DHCP servers for a period of time or establish itself as a DHCP server in man-in-themiddle attacks. Mitigation :- Use DHCP snooping.
ii – Spanning-tree compromises
Attacking device spoofs the root bridge in the STP topology. If successful, the network attacker can see a variety of frames.
Mitigation :- Proactively configure the primary and backup root devices. Enable root guard.
iii – MAC spoofing
Attacking device spoofs the MAC address of a valid host currently in the CAM table. The switch then forwards frames destined for the valid host to the attacking device. Mitigation :- Use DHCP snooping, port security.
iv – Address Resolution Protocol (ARP) spoofing
Attacking device crafts ARP replies intended for valid hosts. The attacking device’s MAC address then becomes the destination address found in the Layer 2 frames sent by the valid network device. Mitigation :- Use Dynamic ARP Inspection, DHCP snooping, port security.
4. Switch Device Attacks
i – Cisco Discovery Protocol (CDP) manipulation Information sent through CDP is transmitted in clear text and unauthenticated, allowing it to be captured and divulge network topology information. Mitigation :- Disable CDP on all ports where it is not intentionally used.
ii – Secure Shell Protocol (SSH) and Telnet attacks
Telnet packets can be read in clear text. SSH is an option but has security issues in version 1. Mitigation : – Use SSH version 2. Use Telnet with vty ACLs.
I was getting this error while removing Operating System ISO image mounted on the Virtual Machine.
What worked for me, is
1. Uncheck the "Connected and Connect at power on" from Device Status.
2. Then Change the Device type from "Datastore ISO File to Client Device" Radio Button
3. and press OK to save the changes.
Note:- I was able to remove the mounted ISO only by directly logging to the ESXi at https://esxi-ip-address/ui
where it asks
"The guest operating system has locked the CD-ROM door and is probably using the CD-ROM, which can prevent the guest from recognizing media changes. If possible, eject the CD-ROM from inside the guest before disconnecting. Disconnect anyway and override the lock?"
You need to select yes to eject the CD-ROM and then remove the ISO file successfully.
While converting physical Windows 7 machine to Virtual machine of infrastructure type, I got this error. The error seems it is unable to read/write source or destination datastore.
I have installed VMware-converter-en-6.2.0-8466193 on Windows 7 physical machine with option locally selected. (not at server/client option)
All of my ESXi servers are connected to the vCenter Server, so I had to use vCenter Server's IP address to send this physical machine to the virtual world.
The issue i found was with the dns resolution to the vCenter Server's hostname. Since I am not using the same dns server on the Windows 7 client machine. So I updated the host entries manually for the vCenter Server's hosname to it IP address.
After adding dns eteries to the hostfile of windows 7, I am not getting this "a file I/O error has occurred while accessing vmware converter" and the migration has started.
Just started using mRemoteNG and its being very cool to connect to different remote connection with different protocols e.g Window Remote Desktop, VNC to Linux, SSH, HTTP connection etc. from a single application.
As new user I configured some remote desktop connection which was quite easy to figure out. But when I wanted to add SSH connections, it came in my mind to import all of the saved connections in the putty. But I couldn't figure it out how can it be done, though it was quite easy and here are the steps.
Open your mRemoteNGCreate a folder if you want segregation of multiple networksCreate a new connectionEnter the IP address of remote server under connection in Config paneUnder the config pane, select protocol "SSH version 2".
Once you select protocol to SSH version 2 you are given option to import putty sessions, as shown in the snap below.
In the above snap, I have imported CSR-AWS session from my saved sessions in Putty.