Clear Manual Ip Address Entries From A Mac

  1. Clear Manual Ip Address Entries From A Machine
  2. Clear Manual Ip Address Entries From A Mac Download

How to Find Your IP Address on a Mac. When your Mac is connected to a network, it is assigned an address on the network called an IP address. The IP address is four sets of digits separated by periods, with up to three digits per set. Usage Guidelines. Use the clear mac address-table dynamic command with no arguments to remove all dynamic entries from the table. To clear static MAC addresses from the table, use the no mac address-table static command. If the clear mac address-table dynamic command is entered with no options, all dynamic addresses are removed. If you specify an address but do not specify an interface, the. I am looking for a signal command that will give me the Ip address of a known MAC address of some system. I dont want the mac address of my own interface. – user770022 Feb 3 '11 at 1:49 ARP will only resolve addresses in your subnet (your 'peers' directly under the nearest switch).

Active1 year, 4 months ago

What is the Linux command to clear IP address of an interface without bringing it down and/or restarting network services. Seems strange ifconfig is able to change IP address but has no option to clear it, or am I wrong?

jackhabjackhab
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4 Answers

Use ip from iproute2. (You need to also specify the prefix length though.)

To remove all addresses (in case you have multiple):

grawitygrawity
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As simple as ifconfig eth0 0.0.0.0. They should have put it in the manual.

JakeGould
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ClearClear Manual Ip Address Entries From A Macjackhabjackhab
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Clear manual ip address entries from a mac 2016

To remove all adreses from all interfaces i used for loop:

erieri

Perhaps you are just looking to get a new IP from the [DHCP-enabled] router? In this case call

dhclient eth0

CodyBugsteinCodyBugstein
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protected by CommunitySep 5 '15 at 16:35

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Configuring the MAC address table

The MAC address table configuration tasks include:

  • Manually configuring MAC address table entries

  • Disabling MAC address learning on a VLAN

  • Configuring the aging timer for dynamic MAC address entries

  • Configuring the MAC learning limit on ports

Enabling MAC address roamingThese configuration tasks are all optional and can be performed in any order.The MAC address table can contain only Layer 2 Ethernet ports and Layer 2 aggregate interfaces.This chapter covers only configuring static, dynamic, and blackhole unicast MAC address table entries.

Manually configuring MAC address table entries

To fence off MAC address spoofing attacks and improve port security, the user can manually add MACaddress table entries to bind ports with MAC addresses.The user can also configure blackhole MAC address entries to filter out packets with certain source ordestination MAC addresses.

To add, modify, or remove entries in the MAC address table in system view:

  1. Enter system view use the command

    system-view

  2. ConfigureMAC addresstable entries:

    • Configure static ordynamic MACAddress TableEntries

      mac-address { dynamic | static } macaddressinterface interface-typeinterface-number vlan vlan-id

    • Configureblackhole MACAddress TableEntries

      mac-address blackhole mac-addressvlan vlan-id

To add or modify a MAC address table entry in interface view:

  1. Enter system view

    system-view

  2. Enter interface view

    interface interface-type interfacenumber

  3. Configure a MAC addresstable entry

    mac-address { dynamic | static }mac-address vlan vlan-id

    NOTE: Ensure that you have created theVLAN and assign the interface tothe VLAN

When the user configures a static MAC address entry on an interface that belongs to a specific isolate-user-VLAN, the user only needs to specify the isolate-user-VLAN, instead of any secondary VLANs associated withthe isolate-user-VLAN.

Disabling MAC address learning on a VLAN

The user may need to disable MAC address learning sometimes to prevent the MAC address table frombeing saturated, for example, when the switch is being attacked by a large amount of packets withdifferent source MAC addresses.The user may disable MAC address learning on a per-VLAN basis.

To disable MAC address learning on a VLAN, perform the following:

  1. Enter system view

    system-view

  2. Enter VLAN view

    vlan vlan-id

  3. Disable MAC addresslearning on the VLAN

    mac-address mac-learning disable

When MAC address learning is disabled, the obtained MAC addresses remain valid until they age out.

Configuring the aging timer for dynamic MAC address entries

The MAC address table uses an aging timer for dynamic MAC address entries for security and efficientuse of table space. If a dynamic MAC address entry has failed to update before the aging timer expires,the device deletes the entry. This aging mechanism ensures that the MAC address table can quicklyupdate to accommodate the latest network changes.

Set the aging timer appropriately. Too long an aging interval might cause the MAC address table toretain outdated entries, exhaust the MAC address table resources, and fail to update its entries toaccommodate the latest network changes. Too short an interval might result in removal of valid entries,causing unnecessary broadcasts, which might affect device performance.

To configure the aging timer for dynamic MAC address entries follow the steps:

  1. Enter system view

    system-view

  2. Configure the agingtimer for dynamicMAC address entries

    mac-address timer {aging seconds | noaging}

    NOTE: Optional.300 seconds by default.The no-aging keyword disables the aging timer.

Reduce broadcasts on a stable network by disabling the aging timer to prevent dynamic entries fromunnecessarily aging out. By reducing broadcasts, not only network performance is improved, but alsosecurity, because the chances for a data packet to reach unintended destinations are reduced.

Configuring the MAC learning limit on ports

As the MAC address table is growing, the forwarding performance of the device might degrade. Toprevent the MAC address table from getting so large that the forwarding performance degrades, the number of MAC addresses can be limited that a port can obtain.

To configure the MAC learning limit on a Layer 2 Ethernet interface or all ports in a port group follow the steps:

  1. Enter system view

    system-view

  2. Enter interface viewor port group view

    • Enter Layer 2 Ethernet interfaceview:

      interface interface-type interfacenumber

    • Enter port group view:

      port-group manual port-groupname

      NOTE: Required.Use either command.Settings in Layer 2 Ethernet interface viewor take effect on the interface only. Settingsin port group view take effect on allmember ports in the port group.
  3. Configure the MAClearning limit on theinterface or portgroup

    mac-address max-mac-count count

    NOTE: Required.No MAC learning limit is configured bydefault.

Enabling MAC address roaming

After the user is enabling MAC address roaming on an IRF fabric, each member switch advertises learned MACaddresses to other member switches.

As Figure 1- MAC address tables of devices when Client A associates with AP C, shows, Device A and Device B form an IRF fabric enabled with MAC address roaming.They connect to AP C and AP D, respectively. When Client A associates with AP C, Device A learns theMAC address of Client A and advertises it to the member switch Device B.

Figure 1: MAC address tables of devices when Client A associates with AP C

If Client A roams to AP D, Device B learns the MAC address of Client A and advertises it to Device A toensure service continuity for Client A, as shown in Figure 2 - MAC address tables of devices when Client A roams to AP D.

Figure 2: MAC address tables of devices when Client A roams to AP D

To enable MAC address roaming, perform the following:

  1. Enter system view

    system-view

  2. Enable MAC addressroaming

    mac-address mac-roaming enable

Displaying and maintaining MAC address tables

  1. Display MAC address tableinformation

    display mac-address [ mac-address [ vlan vlan-id ]| [ [ dynamic | static ] [ interface interface-typeinterface-number ] | blackhole ] [ vlan vlan-id ] [count ] ] [ | { begin | exclude | include } regularexpression]

  2. Display the aging timer fordynamic MAC addressentries

    display mac-address aging-time [ | { begin |exclude | include } regular-expression ]

  3. Display the system orinterface MAC addresslearning state

    display mac-address mac-learning [ interface-typeinterface-number ] [ | { begin | exclude | include }regular-expression ]

  4. Display MAC addressstatistics

    display mac-address statistics [ | { begin | exclude| include } regular-expression ]

MAC address table configuration example

Network requirements
  • The MAC address of Host A is 000f-e235-dc71 and belongs to VLAN 1. It is connected toGigabitEthernet 1/0/1 of the device. To prevent MAC address spoofing, add a static entry for thehost in the MAC address table of the device.

  • The MAC address of Host B is 000f-e235-abcd and belongs to VLAN 1. For security, because thishost once behaved suspiciously on the network, add a blackhole MAC address entry for the hostMAC address, so that all packets destined for the host will be dropped.

  • Set the aging timer for dynamic MAC address entries to 500 seconds.

Configuration procedure

  • # Add a static MAC address entry.

    <Sysname> system-view
    [Sysname] mac-address static 000f-e235-dc71 interface gigabitethernet 1/0/1 vlan 1

  • # Add a destination blackhole MAC address entry.

    [Sysname] mac-address blackhole 000f-e235-abcd vlan 1

  • # Set the aging timer for dynamic MAC address entries to 500 seconds.

    [Sysname] mac-address timer aging 500

  • # Display the MAC address entry for port GigabitEthernet 1/0/1.

    [Sysname] display mac-address interface gigabitethernet 1/0/1
    MAC ADDR VLAN ID STATE PORT INDEX AGING TIME
    000f-e235-dc71 1 Config static GigabitEthernet 1/0/1 NOAGED
    --- 1 mac address(es) found ---

  • # Display information about the destination blackhole MAC address table.

    [Sysname] display mac-address blackhole
    MAC ADDR VLAN ID STATE PORT INDEX AGING TIME
    000f-e235-abcd 1 Blackhole N/A NOAGED
    --- 1 mac address(es) found ---

  • # View the aging time of dynamic MAC address entries.

    [Sysname] display mac-address aging-time
    Mac address aging time: 500s

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