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[ScreenOS] What is 'ICMP Ping ID Zero Protection' Screen Protection?



Article ID: KB8342 KB Last Updated: 03 Sep 2020Version: 7.0

Understanding 'ICMP Ping ID Zero Protection' Screen Protection.


The ICMP header has the following information:

    Type: 8 (Echo (ping) request)
    Code: 0
    Checksum: 0xd455 [correct]
    Identifier: 0x0300
    Sequence number: 0x7606
    Data (32 bytes)

The Screen Options 'ICMP Ping ID Zero protection' will drop packets if either a Echo Request or Echo Reply packet is received with Identifier as Zero.  The Identifier and Sequence Number is used to match ICMP sessions on the firewall.

Below is the packet dump from the sniffer trace with good ICMP packet:

Ethernet II, Src: Ibm_76:5d:03 (00:0d:60:76:5d:03), Dst: IETF-VRRP-virtual-router-VRID_1c (00:00:5e:00:01:1c)
    Destination: IETF-VRRP-virtual-router-VRID_1c (00:00:5e:00:01:1c)
    Source: Ibm_76:5d:03 (00:0d:60:76:5d:03)
    Type: IP (0x0800)

Internet Protocol, Src: (, Dst: (
    Version: 4
    Header length: 20 bytes
    Differentiated Services Field: 0x00 (DSCP 0x00: Default; ECN: 0x00)
        0000 00.. = Differentiated Services Codepoint: Default (0x00)
        .... ..0. = ECN-Capable Transport (ECT): 0
        .... ...0 = ECN-CE: 0
    Total Length: 60
    Identification: 0x16b1 (5809)
    Flags: 0x00
        0... = Reserved bit: Not set
        .0.. = Don't fragment: Not set
        ..0. = More fragments: Not set
    Fragment offset: 0
    Time to live: 128
    Protocol: ICMP (0x01)
    Header checksum: 0x7b7e [correct]
        Good: True
        Bad : False
    Source: (
    Destination: (

Internet Control Message Protocol
    Type: 8 (Echo (ping) request)
    Code: 0
    Checksum: 0xd455 [correct]
    Identifier: 0x0300
    Sequence number: 0x7606
    Data (32 bytes)


Modification History:
2020-09-03: Article reviewed for accuracy. Non-technical changes done.
2019-05-06: Content reviewed for accuracy
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