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Disabling forwarding ICMP fragments
Restrictions and guidelines
Disabling forwarding ICMP fragments can protect your device from ICMP fragment attacks.
Procedure
1. Enter system view.
system-view
2. Disable forwarding ICMP fragments.
ip icmp fragment discarding
By default, forwarding ICMP fragments is enabled.
Specifying the source address for ICMP packets
About specifying source address for ICMP packets
Specifying the source IP address for outgoing ping echo requests and ICMP error messages helps
users to locate the sending device easily. As a best practice, specify the IP address of the loopback
interface as the source IP address.
Restrictions and guidelines
If you specify an IP address in the ping command, ping echo requests use the specified address as
the source IP address rather than the IP address specified by the
ip icmp source command.
Procedure
1. Enter system view.
system-view
2. Specify the source address for outgoing ICMP packets.
ip icmp source ip-address
By default, no source address is specified for outgoing ICMP packets. The device uses the IP
address of the sending interface as the source IP address for outgoing ICMP packets.
Setting TCP MSS for an interface
About TCP MSS
The maximum segment size (MSS) option informs the receiver of the largest segment that the
sender can accept. Each end announces its MSS during TCP connection establishment. If the size
of a TCP segment is smaller than the MSS of the receiver, TCP sends the TCP segment without
fragmentation. If not, it fragments the segment according to the receiver's MSS.
Restrictions and guidelines
• If you set the TCP MSS on an interface, the size of each TCP segment received or sent on the
interface cannot exceed the MSS value.
• This configuration takes effect only for TCP connections established after the configuration
rather than the TCP connections that already exist.
• This configuration is effective only for IP packets.
Procedure
1. Enter system view.
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