Disabling Sending Of Icmp Error Packets - 3Com WX3000 Series Operation Manual

To do...
Enter system view
Configure TCP synwait
timer's timeout value
Configure TCP finwait timer's
timeout value
Configure the size of TCP
receive/send buffer

Disabling Sending of ICMP Error Packets

Sending error packets is a major function of ICMP protocol. In case of network abnormalities, ICMP
packets are usually sent by the network or transport layer protocols to notify corresponding devices so
as to facilitate control and management.
By default, the device supports sending ICMP redirect and destination unreachable packets.
Although sending ICMP error packets facilitate control and management, it still has the following
disadvantages:
Sending a lot of ICMP packets will increase network traffic.
If receiving a lot of malicious packets that cause it to send ICMP error packets, the device's
performance will be reduced.
As the ICMP redirection function increases the routing table size of a host, the host's performance
will be reduced if its routing table becomes very large.
If a host sends malicious ICMP destination unreachable packets, end users may be affected.
To prevent the above mentioned problems, you can disable the device from sending such ICMP error
packets.
Follow these steps to disable sending of ICMP error packets:
To do...
Enter system view
Disable sending of ICMP
redirects
Disable sending of ICMP
destination unreachable
packets
Use the command...
system-view
tcp timer syn-timeout
time-value
tcp timer fin-timeout
time-value
tcp window window-size
Use the command...
system-view
undo icmp redirect send
undo icmp unreach send
2-2
Remarks
—
Optional
By default, the timeout value is 75
seconds.
Optional
By default, the timeout value is
675 seconds.
Optional
By default, the buffer is 8
kilobytes.
Remarks
—
Required
Enabled by default
Required
Enabled by default