Mac address table static switchport port security
This was an issue for us even without manually or sticky MAC addresses. Normally this wouldn't be an issue as the switch would forget the MAC once link went down. However with a VoIP phone in place the link never went down. We resolved this by putting in an inactivity timer to automatically age out old entries. Good article on the basics of Port Security.
I've recently had to use this to provisionally secure ports from rogue end-user points and it worked well. Certainly port-security isn't the end all be all I solved this by setting age to 1 minute. I think with these 4 things installed you have secure enough environment without paying for One important "gotcha" to remember when configuring port security, no matter how you configure it, you still need the "switchport port-security" command with no parameters to enable it.
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For instance, I see this all the time:. So many times I've been told that port security was configured, only to find that it wasn't enabled with the generic version of the command. If you want to use HSRP with port-security and keep to the default of one MAC address per switchport you can use the following command on the routers:.
Thanks for the article. We use it as hexem mentioned - as protection against MAC flood attacks. In fact, that's what the Cisco chaps were advising at Networkers this year for the reasons covered above. Here is our edge port port-security config:.
Be aware that sticky mac addresses do not expire, hence the errdisable ports cannot auto recover if sticky mac addresses are enabled. I have configured one port in a x series with the following commands and the Voip phone was showing " configuring IP address". Also remember that if you are using sticky, you need to make sure your WRITE your config after all addresses are learned. Otherwise, if the switch loses power, all ports will dynamically relearn new mac's when it comes up.
Hi, grrreat site. I'm going for CCNP switch and found this on the site which i'm following for a long time. Port Security By stretch Monday, May 3, at a. Tweaking Port Security Violation Mode Port security can be configured to take one of three actions upon detecting a violation: shutdown default ; The interface is placed into the error-disabled state, blocking all traffic. This can be modified, for example, to accommodate both a host and an IP phone connected in series on a switch port: Switch config-if switchport port-security maximum 2 One also has the option to set a maximum MAC count for the access and voice VLANs independently assuming a voice VLAN has been configured on the interface : Switch config-if switchport port-security maximum 1 vlan access Switch config-if switchport port-security maximum 1 vlan voice MAC Address Learning An administrator has the option of statically configuring allowed MAC addresses per interface.
Catalyst 4500 Series Switch Cisco IOS Software Configuration Guide, 12.2(25)EW
Switch config-if switchport port-security mac-address b. Current configuration : bytes! Switch config-if no switchport port-security mac-address b. Auto-recovery To avoid having to manually intervene every time a port-security violation forces an interface into the error-disabled state, one can enable auto-recovery for port security violations.
Configuring Sticky Switchport Security | Free CCNA Workbook
Footnote Although a deterrent, port security is not a reliable security feature, as MAC addresses are trivially spoofed, and multiple hosts can still easily be hidden behind a small router. Support PacketLife by buying stuff you don't need! I'll be making some changes based on the above. Cheers mate! You can use the port security feature to restrict input to an interface by limiting and identifying MAC addresses of the workstations that are allowed to access the port. When you assign secure MAC addresses to a secure port, the port does not forward packets with source addresses outside the group of defined addresses.
If you limit the number of secure MAC addresses to one and assign a single secure MAC address, the workstation attached to that port is assured the full bandwidth of the port. If a port is configured as a secure port and the maximum number of secure MAC addresses is reached, when the MAC address of a workstation attempting to access the port is different from any of the identified secure MAC addresses, a security violation occurs.
After you have set the maximum number of secure MAC addresses on a port, the secure addresses are included in an address table in one of these ways:. Note If the port shuts down, all dynamically learned addresses are removed. These can be dynamically learned or manually configured, stored in the address table, and added to the running configuration.
If these addresses are saved in the configuration file, the interface does not need to dynamically relearn them when the switch restarts. Although sticky secure addresses can be manually configured, it is not recommended. You can configure an interface to convert the dynamic MAC addresses to sticky secure MAC addresses and to add them to the running configuration by enabling sticky learning.
To enable sticky learning, enter the switchport port-security mac-address sticky command. When you enter this command, the interface converts all the dynamic secure MAC addresses, including those that were dynamically learned before sticky learning was enabled, to sticky secure MAC addresses. The sticky secure MAC addresses do not automatically become part of the configuration file, which is the startup configuration used each time the switch restarts.
If you save the sticky secure MAC addresses in the configuration file, when the switch restarts, the interface does not need to relearn these addresses. If you do not save the configuration, they are lost. If sticky learning is disabled, the sticky secure MAC addresses are converted to dynamic secure addresses and are removed from the running configuration. After the maximum number of secure MAC addresses is configured, they are stored in an address table. To ensure that an attached device has the full bandwidth of the port, configure the MAC address of the attached device and set the maximum number of addresses to one, which is the default.
Note When a Catalyst series switch port is configured to support voice as well as port security, the maximum number of allowable MAC addresses on this port should be changed to three. A security violation occurs if the maximum number of secure MAC addresses has been added to the address table and a workstation whose MAC address is not in the address table attempts to access the interface. You can configure the interface for one of these violation modes, based on the action to be taken if a violation occurs:.
The rate at which SNMP traps are generated can be controlled by the snmp-server enable traps port-security trap-rate command. The default value "0" causes an SNMP trap to be generated for every security violation. When a secure port is in the error-disabled state, you can bring it out of this state by entering the errdisable recovery cause psecure-violation global configuration command or you can manually reenable it by entering the shutdown and no shut down interface configuration commands. Before continuing, visit the following link to learn more about MAC flooding attack MAC address flooding attack CAM table flooding attack is a type of network attack where an attacker connected to a switch port floods the switch interface with very large number of Ethernet frames with different fake source MAC address.
OmniSecuSW1 config-if switchport port-security maximum? Maximum addresses 3 Define the MAC Addresses of known devices, which are going to access the network via that interface. The default number of known secure MAC addresses is one. OmniSecuSW1 config-if switchport port-security mac-address? H 48 bit mac address sticky Configure dynamic secure addresses as sticky 4 Specify an action to do when a violation occurred on above conditions.
The default violation action is to shut down the port.
Configuring Port Security
OmniSecuSW1 config-if switchport port-security violation? Related Tutorials. If you are experiencing distorted display, change your screen resolution to x pixels.
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