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Cisco ASA 5500 Series Configuration Guide using ASDM
OL-20339-01
Chapter 48 Configuring Connection Settings
Configuring Connection Settings
Step 8 Click OK.
Configuring Connection Settings
To set connection settings, perform the following steps.
Detailed Steps
Step 1 Configure a service policy on the Configuration > Firewall > Service Policy Rules pane according to
Chapter 29, “Configuring a Service Policy.”
You can configure connection limits as part of a new service policy rule, or you can edit an existing
service policy.
Step 2 On the Rule Actions dialog box, click the Connection Settings tab.
Step 3 To set maximum connections, configure the following values in the Maximum Connections area:
• TCP & UDP Connections—Specifies the maximum number of simultaneous TCP and UDP
connections for all clients in the traffic class, up to 65,536. The default is 0 for both protocols, which
means the maximum possible connections are allowed.
• Embryonic Connections—Specifies the maximum number of embryonic connections per host up to
65,536. An embryonic connection is a connection request that has not finished the necessary
handshake between source and destination. This limit enables the TCP Intercept feature. The default
is 0, which means the maximum embryonic connections. TCP Intercept protects inside systems from
a DoS attack perpetrated by flooding an interface with TCP SYN packets. When the embryonic limit
has been surpassed, the TCP intercept feature intercepts TCP SYN packets from clients to servers
on a higher security level. SYN cookies are used during the validation process and help to minimize
the amount of valid traffic being dropped. Thus, connection attempts from unreachable hosts will
never reach the server.
• Per Client Connections—Specifies the maximum number of simultaneous TCP and UDP
connections for each client. When a new connection is attempted by a client that already has opened
the maximum per-client number of connections, the adaptive security appliance rejects the
connection and drops the packet.
• Per Client Embryonic Connections—Specifies the maximum number of simultaneous TCP
embryonic connections for each client. When a new TCP connection is requested by a client that
already has the maximum per-client number of embryonic connections open through the adaptive
security appliance, the adaptive security appliance proxies the request to the TCP Intercept feature,
which prevents the connection.
Step 4 To configure connection timeouts, configure the following values in the TCP Timeout area:
• Connection Timeout—Specifies the idle time until a connection slot (of any protocol, not just TCP)
is freed. Enter 0:0:0 to disable timeout for the connection. This duration must be at least 5 minutes.
The default is 1 hour.
• Send reset to TCP endpoints before timeout—Specifies that the adaptive security appliance should
send a TCP reset message to the endpoints of the connection before freeing the connection slot.
• Embryonic Connection Timeout—Specifies the idle time until an embryonic connection slot is
freed. Enter 0:0:0 to disable timeout for the connection. The default is 30 seconds.
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