2-2
To do… Use the command… Remarks
Enter system view system-view —
Configure TCP synwait
timer’s timeout value tcp timer syn-timeout
time-value
Optional
By default, the timeout value is 75
seconds.
Configure TCP finwait timer’s
timeout value tcp timer fin-timeout
time-value
Optional
By default, the timeout value is
675 seconds.
Configure the size of TCP
receive/send buffer tcp window window-size Optional
By default, the buffer is 8
kilobytes.
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:
z Sending a lot of ICMP packets will increase network traffic.
z If receiving a lot of malicious packets that cause it to send ICMP error packets, the device’s
performance will be reduced.
z 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.
z 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… Use the command… Remarks
Enter system view system-view —
Disable sending of ICMP
redirects undo icmp redirect send Required
Enabled by default
Disable sending of ICMP
destination unreachable
packets undo icmp unreach send Required
Enabled by default