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Brian_Durkin_14's avatar
Brian_Durkin_14
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Nov 18, 2014

BigIP LTM is reponded ping requests for address that do not exist in our network

Our network personnel have informed my that our non-production BigIP LTM is responding to ping requests of addresses that do not exist in our network.

 

Question: why is the BigIP responding any ping requests? Should it be routing the ICMP traffic through the to the hosts? Question: how can we stop the BigIP from responding to ping request to non-existing address?

 

11 Replies

  • If it's responding to pings from addresses not on your network, then it sounds like your network guys may need to look at their ACLs... it sounds like there may be more to this issue than what is presented here.

     

    Which addresses on your LTM are responding to pings? It is one of your virtual servers or the management interface? Regardless, you can firewall off any ICMP requests that hit the LTM.

     

  • Actually, this is a known issue with BigIP:

     

    sol15469: Loading the BIG-IP configuration from the command line may incorrectly enable ICMP Echo for virtual addresses

     

    There are two solutions: 1.Disable ICMP Echo for a virtual address using the following command syntax: tmsh modify ltm virtual-address icmp-echo

     

    1. upgrade the S/W to from 11.5.1 to 11.6.0.
  • shaggy's avatar
    shaggy
    Icon for Nimbostratus rankNimbostratus

    the f5 can respond to pings for addresses it owns (Self-IP, SNAT, virtual IP addresses). I believe that it can respond to ICMP requests for networks that are defined in its virtual address list as well. If you have any network virtual servers (IP forwarding, fast-l4, etc.), verify that those network virtual addresses have ICMP disabled. Navigate to Local Traffic | Virtual Servers | Virtual Address List, click on the network address, and verify "ICMP Echo" is disabled. keep in mind, depending on the forwarding-vs configuration, this could prevent ICMP messages from being passed through to backend networks

     

  • Thanks Shaggy; I will take that into consideration if I disable the ICMP echo. Brian

     

  • what about hosts that do not exist ? We ran a vulnerability scan on subnets that sit on the F5, we received a reply from ips that are not on the subnet yet.

     

  • what about hosts that do not exist ? We ran a vulnerability scan on subnets that sit on the F5, we received a reply from ips that are not on the subnet yet.

    do you have network virtual server address with enabling arp and icmp-echo?

    root@(ve11b)(cfg-sync In Sync)(Active)(/Common)(tmos) list ltm virtual-address 192.168.0.0 all-properties
    ltm virtual-address 192.168.0.0 {
        address 192.168.0.0
        app-service none
        arp enabled
        auto-delete true
        connection-limit 0
        description none
        enabled yes
        floating enabled
        icmp-echo enabled
        inherited-traffic-group false
        mask 255.255.255.0
        metadata none
        partition Common
        route-advertisement disabled
        server-scope any
        traffic-group traffic-group-1
        unit 1
    }
    
    • pdiab_72047's avatar
      pdiab_72047
      Icon for Nimbostratus rankNimbostratus
      it is actually a directly connected network and not a VIP subnet. Why would F5 in the first place reply for a host that doesnt exist on that subnet and it looks like the MAC is for the vlan on the F5 and not the physical interface on the F5
  • what about hosts that do not exist ? We ran a vulnerability scan on subnets that sit on the F5, we received a reply from ips that are not on the subnet yet.

    do you have network virtual server address with enabling arp and icmp-echo?

    root@(ve11b)(cfg-sync In Sync)(Active)(/Common)(tmos) list ltm virtual-address 192.168.0.0 all-properties
    ltm virtual-address 192.168.0.0 {
        address 192.168.0.0
        app-service none
        arp enabled
        auto-delete true
        connection-limit 0
        description none
        enabled yes
        floating enabled
        icmp-echo enabled
        inherited-traffic-group false
        mask 255.255.255.0
        metadata none
        partition Common
        route-advertisement disabled
        server-scope any
        traffic-group traffic-group-1
        unit 1
    }
    
    • pdiab_72047's avatar
      pdiab_72047
      Icon for Nimbostratus rankNimbostratus
      it is actually a directly connected network and not a VIP subnet. Why would F5 in the first place reply for a host that doesnt exist on that subnet and it looks like the MAC is for the vlan on the F5 and not the physical interface on the F5