nvt_tune.h(SFF)

Description

Some parameters use clock ticks as the unit of measure. The kernel variable HZ represents the number of clock ticks per second. HZ is currently set to 100 in accordance with Intel Binary Compatibility Standard 2 (iBCS2).

The following parameters may be used to tune the performance of NVT:

NVT_MAX_LOGINS

Specifies the maximum number of NVT connections that the NVT protocol driver can service simultaneously. It also defines the maximum value for the nvt_max_logins parameter in the NPSConfig file.

The default (and absolute minimum) is 50. Increase its value if the host can handle more NVT sessions.

NVT_SAP_FREQ

Specifies the number of seconds between SAP broadcasts advertising the NVT service. SAP agents expect to receive a SAP broadcast every minute. If a service is not heard from for three minutes, the SAP agent assumes that the service has gone down and removes the service from its tables.

The default is 50 seconds.

NVT_MAX_RETRYS

Specifies the number of times a packet is re-sent to a client that is not acknowledging a data packet. If this maximum is reached, NVT breaks the connection.

The default is 120. Increase its value if NVT is used on a large Internet with many slow or unreliable routers between the client and the host. Decrease its value if you want to detect downed clients quicker and to reduce the number of times a packet is re-sent.

NVT_START_RETRY_TIME

Specifies the number of ticks NVT waits to receive an acknowledgment. This value is the interval between the first send and the first retry.

The default is 80 ticks. Increase its value if NVT is used on a large Internet with many routers between the client and the host. Decrease its value if NVT is used on a network with little traffic or few routers between the client and the host.

NVT_MIN_SINGLE_RETRY_TIME

Specifies the minimum number of ticks NVT waits before resending packets. The first time a packet is sent, NVT uses the NVT_START_RETRY_TIME value. On subsequent resends, NVT waits two times the average turnaround time for a packet. If this turnaround value is less than the NVT_MIN_SINGLE_RETRY_TIME, value, NVT uses the NVT_MIN_SINGLE_RETRY_TIME value.

The default is 120 ticks. Increase its value if NVT is used on a large Internet with many routers between the client and the host. Decrease its value if NVT is used on a network with little traffic or few routers between the client and the host.

NVT_MAX_SINGLE_RETRY_TIME

Specifies the maximum number of ticks NVT will wait before resending packets. The first time a packet is re-sent, NVT uses the NVT_START_RETRY_TIME value. The second (and subsequent) times NVT resends the packet, NVT waits two times the average turnaround time for a packet. If this value is greater than the NVT_MAX_SINGLE_RETRY_TIME value, NVT uses the NVT_MAX_SINGLE_RETRY_TIME value.

The default is 480 ticks. Increase its value if NVT is used on a large Internet with many routers between the client and the host. Decrease its value if NVT is used on a network with little traffic or few routers between the client and the host.

NVT_KEEP_ALIVE_INTERVAL_TIME

Specifies how long NVT should wait before sending a watchdog packet to determine if a connection is inactive.

The default is 7200 ticks. Increase its value if NVT is used on a large Internet with slow routers between the client and the host. Decrease its value if you want the host to detect downed clients quicker.

NVT_MAX_KEEP_ALIVES

Specifies the maximum number of watchdog (keep alive) packets that are sent to a client that is not acknowledging watchdog packets. When NVT has sent out this maximum number of packets, NVT assumes that the connection is dead and clears that connection.

The default is 15. Increase its value if NVT is used on a large Internet with unreliable or slow routers between the client and the host. Decrease its value if you want to detect downed clients quicker and to reduce the number of times a watchdog packet is sent to a client.

Files

See also