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124 ServerIron ADX Security Guide
53-1002440-03
DDoS protection
5
TABLE 11 Output Descriptions for show server syn-cookie
DDoS protection
A Distributed Denial of Service (DDoS) attack is employed to cause a denial of service to legitimate
users by consuming all or most of the CPU and memory resources on a ServerIron ADX or on real
servers. The ServerIron ADX provides protection and prevents well-known DDoS attacks such as
Xmas-tree attack, syn fragment, address sweep and others. The ServerIron ADX prevents these
attacks by defining filters for each type of attack coupled with a drop or log action. These filters are
then bound to an interface. All packets that match the filter on the bound interface are dropped or
logged as defined in the configuration. Filters can be defined according to a generic rule as shown
in “Configuring a Generic Rule” on page 125 or applied from built-in rules as described in Table 13,
Table 15, Table 16 and Table 17. Filters are applied to IPv4 and IPv6 traffic where appropriate.
The following sections describe how to configure a security filter, define rules within a security filter
and bind a security filter to an interface.
• “Configuring a security filter” on page 125
• “Configuring a Generic Rule” on page 125
• “Configuring a rule for common attack types” on page 127
• “Configuring a rule for ip-option attack types” on page 129
• “Configuring a rule for icmp-type options” on page 130
• “Configuring a rule for IPv6 ICMP types” on page 131
• “Configuring a rule for IPv6 ext header types” on page 132
• “Binding the filter to an interface” on page 133
Field Description
CPU SYNs rcvd
AXP SYNs rcvd Number of SYNs received on ServerIron ADX ports that have the Syn-Proxy feature
enabled.
CPU SYN-ACKs sent
AXP SYN-ACKs sent Number of SYN ACKs sent from the ServerIron ADX to the client
CPU Valid ACKs rcvd
AXP Valid ACKs rcvd Number of valid ACKs received from the client.
Invalid ACKs rcvd Number or invalid ACKs received from the client.
ACL passed Number of ACL lookups that the ServerIron ADX passed.
ACL failed Number of ACL lookups that the ServerIron ADX denied.
Frags allowed Number of fragmented packets allowed.
Frags dropped Number of fragmented packets dropped.
ACK without datp dro:
Invalid vport