UDPCONFIG statement

Parameters

EPHEMERALPORTS low_port high_port

Indicates the range of ephemeral ports that are to be assigned at bind time. The default ephemeral port range is 1024 - 65535.

low_port

The starting port for the range of ports. The low_port value is in the range 1024 - 65535.

high_port

The ending port for the range of ports. The high_port value is in the range 1024 – 65535, and must be greater than or equal to the low_port value.

Guideline: Any ports that are reserved using port reservation definitions that are within the EPHEMERALPORTS range are excluded from the EPHEMERALPORTS pool, effectively making the pool smaller.

Restriction: Ports that are defined by BPXPARMS INADDRANYPORT and INADDRANYCOUNT must be restricted by the PORT or PORTRANGE statement to the job name OMVS. These ports will not be assigned by the stack unless the user has the job name of OMVS.

RESTRICTLOWPORTS | UNRESTRICTLOWPORTS

RESTRICTLOWPORTS

When set, ports 1 - 1023 are reserved for users by the PORT and PORTRANGE statements. The RESTRICTLOWPORTS parameter is confirmed by the message:

EZZ0338I UDP PORTS 1 THRU 1023 ARE RESERVED 

Applications can be authorized to low ports in the following ways:

• By way of PORT or PORTRANGE with the appropriate job name or a wildcard job name such as * or OMVS. If the SAF keyword is used on PORT or PORTRANGE, additional access restrictions can be imposed by a security product (for example, RACF®).
• APF authorized applications can access unreserved low ports.
• OMVS superuser (UID(0)) applications can access unreserved low ports.

Applications that have a dependency on being able to obtain an available port in the 1- 1023 range without having that port explicitly reserved for its use should be run as APF authorized or superuser. Use RESTRICTLOWPORTS to increase system security.

UNRESTRICTLOWPORTS

Ports 1 - 1023 are not reserved. This is the default value. The UNRESTRICTLOWPORTS parameter is confirmed by the message:

EZZ0338I UDP PORTS 1 THRU 1023 ARE NOT RESERVED 

UDPCHKSUM | NOUDPCHKSUM

NOUDPCHKSUM

Used to ensure UDP does not do check summing. This option is ignored for UDP datagrams flowing over an IPv6 network, as UDP Checksum is a required function on an IPv6 network. If an AF_INET6 socket is used to send datagrams over an IPv4 network, this option disables the UDP checksum function.

UDPCHKSUM

Used to ensure UDP does check summing. This is the default value.

UDPQUEUELIMIT | NOUDPQUEUELIMIT

NOUDPQUEUELIMIT

Used to specify that UDP should not have a queue limit. With NOUDPQUEUELIMIT specified, it is possible for inbound datagrams to arrive and be queued to a UDP application's socket faster than the application can receive the datagrams. If so, the amount of data queued could be substantial, resulting in a possible shortage of system storage. For this reason, set a limit using UDPQUEUELIMIT or by using an IDS Traffic Regulation policy. The NOUDPQUEUELIMIT parameter is confirmed by the message:

EZZ0336I NO LIMIT ON INCOMING UDP DATAGRAM QUEUE SET

If intrusion detection services (IDS) Traffic Regulation (TR) policy is in effect for a UDP port then NOUDPQUEUELIMIT is overridden for that port.

UDPQUEUELIMIT

Used to set a queue limit for UDP. If set, then a maximum of 2000 incoming datagrams are queued on a UDP socket. This is the default value. The UDPQUEUELIMIT parameter is confirmed by the message:

EZZ0336I A LIMIT ON INCOMING UDP DATAGRAM QUEUE SET

If intrusion detection services (IDS) Traffic Regulation (TR) policy is in effect for a UDP port, the queue limit size is controlled by the policy for that port.

UDPRCVBUFRSIZE udp_receive_buffer_size

The UDP receive buffer size. Valid values are in the range 1 - 65535. The default is 65535.

UDPSENDBFRSIZE udp_send_buffer_size

The UDP send buffer size. Valid values are in the range 1 - 65535. The default is 65535.

Steps for modifying

To modify parameters for the UDPCONFIG statement, you must respecify the statement with the new parameters.