Configuring The Tcp Buffer Size; Configuring Tcp Timers; Enabling Sending Icmp Error Messages - HP FlexNetwork MSR2003 Configuration Manual

SYN Cookie can protect the server from SYN Flood attacks. When the server receives a SYN packet,
it responds with a SYN ACK packet without establishing a TCP semi-connection. The server
establishes a TCP connection and enters ESTABLISHED state only when it receives an ACK packet
from the client.
To enable TCP SYN Cookie:
Step
1. Enter system view.
2. Enable SYN Cookie.

Configuring the TCP buffer size

Step
1. Enter system view.
2. Configure the size of TCP
receive/send buffer.

Configuring TCP timers

You can configure the following TCP timers:
•
SYN wait timer—TCP starts the SYN wait timer after sending a SYN packet. Within the SYN
wait timer if no response is received or the upper limit on TCP connection tries is reached, TCP
fails to establish the connection.
•
FIN wait timer—TCP starts the FIN wait timer when the state changes to FIN_WAIT_2. If no
FIN packet is received within the timer interval, TCP terminates the connection. If a FIN packet
is received, TCP changes the connection state to TIME_WAIT. If a non-FIN packet is received,
TCP restarts the timer, and tears down the connection when the timer expires.
To configure TCP timers:
Step
1. Enter system view.
2. Configure TCP
timers.

Enabling sending ICMP error messages

Perform this task to enable sending ICMP error messages, including redirect, time exceeded, and
destination unreachable messages.
•
ICMP redirect messages
A host that has only one default route sends all packets to the default gateway. The default
gateway sends an ICMP redirect message to inform the host of a correct next hop by following
these rules:
The receiving and sending interfaces are the same.
Command
system-view
tcp syn-cookie enable
Command
system-view
tcp window
window-size
Command
system-view
•
Configure the TCP SYN wait timer:
tcp timer syn-timeout time-value
•
Configure the TCP FIN wait timer:
tcp timer fin-timeout time-value
190
Remarks
N/A
The default setting is disabled.
Remarks
N/A
The default buffer size is 64 KB.
Remarks
N/A
By default:
•
The TCP SYN wait timer is 75
seconds.
•
The TCP FIN wait timer is
675 seconds.