sys_attrs_inet(5) File Formats Manual sys_attrs_inet(5)
NAME
sys_attrs_inet - inet subsystem attributes
DESCRIPTION
This reference page lists and describes attributes for the Internet (inet) kernel subsystem. Refer to the sys_attrs(5) reference page for
an introduction to the topic of kernel subsystem attributes.
The number of hash buckets in the kernel interface alias table (in_ifaddr). The value of the inifaddr_hsize attribute is always
rounded down to the nearest power of 2. The maximum value is 512.
Default value: 32 (hash buckets)
Minimum value: 16
Maximum value: 512
The default Internet Protocol (IP) time-to-live value.
Default value: DEFTTL, or 64 (router hops)
Minimum value: 0
Maximum value: 255
A value that enables (1) or disables (0) a check to determine whether an IP datagram whose destination address is a directed broad-
cast address has been received on the interface corresponding to that broadcast address.
Default value: 0 (disabled)
A value that enables (1) or disables (0) a system's ability to forward IP packets that are not addressed to the system. This func-
tionality is usually enabled by using the /usr/sbin/iprsetup command.
Default value: 0 (disabled)
For systems functioning as routers, both ipforwarding and ipgateway attributes must be 1.
Maximum time an IP fragment can spend waiting to be reassembled.
Default value: IPFRAGTTL (60, in units of .5 seconds, or 30 seconds)
Minimum value: 1
Maximum value: INT_MAX, or 2 billion
A value that enables (1) or disables (0) a system's ability to forward IP packets that are not addressed to the system. This func-
tionality is usually enabled by using the /usr/sbin/iprsetup command.
Default value: 0 (disabled)
For systems functioning as routers, both ipforwarding and ipgateway attributes must be 1.
The number of times a system can simultaneously make outgoing connections to other systems. The number of outgoing ports is the
value of the ipport_userreserved attribute minus the value of the ipport_userreserved_min attribute. The default value of the
attribute is 5000; therefore, the default number of outgoing ports is 3976.
Default value: 5000
Minimum value: 1
Maximum value: 65535
The lower limit of range of port numbers available for use by a TCP or UDP application. The number of outgoing ports is the value
of the ipport_userreserved attribute minus the value of the ipport_userreserved_min attribute. The default value of the attribute
is 5000; therefore, the default number of outgoing ports is 3976.
Default value: 1024
Minimum value: 1
Maximum value: 65535
Maximum length of the IP input queue (ipintrq) before input packets are dropped.
Default value: 1024 (bytes)
Minimum value: 1024
Maximum value: 65535
Maximum number of IP input queues.
Default value: 1 (queues)
Minimum value: 1
Maximum value: 64
A value that enables (1) or disables (0) the sending of ICMP redirect messages.
Default value: 1 (enabled)
Enables (1) or disables (0) source routing.
Default value: 1 (enabled)
Time to wait after a decrease in a PMTU value before attempting to determine if the PMTU value has increased.
Default value: PMTU_DECREASE_INTVL, or 1200 (in units of .5 seconds)
Minimum value: 1
Maximum value: UINT_MAX, or 4 billion
A value that enables (1) or disables (0) discovery of the path maximum transfer unit (PMTU).
Default value: 1 (enabled)
Time to wait after an increase in a PMTU value before attempting to determine if the PMTU has increased.
Default value: PMTU_INCREASE_INTVL, or 240 (in units of .5 seconds)
Minimum value: 1
Maximum value: UINT_MAX, or 4 billion
The timer processing interval for routes participating in the PMTU discovery process.
Default value: PMTU_RT_CHECK_INTVL, or 20 (in units of .5 seconds)
Minimum value: 1
Maximum value: UINT_MAX, or 4 billion
A value that enables (1) or disables (0), consideration of all IP addresses in the same network as being local. When this value is
1, all IP addresses that are in different subnets but in the same network are considered local. When this value is 0, only the IP
addresses that match a directly connected subnet are considered local.
Default value: 1 (enabled)
The number of Transmission Control Protocol (TCP) hash tables.
Default value: 1 (table)
Minimum value: 1
Maximum value: 64
The number of buckets in the TCP inpcb hash table.
Default value: 512 (buckets)
Minimum value: 0
Maximum value: INT_MAX, or 2 billion
Enables (1) or disables (0) optimization of the listen path for server sockets.
Default value: 1 (enabled)
A value that enables (1) or disables (0) 4.2 BSD-compatible behavior for the initial send sequence of numbers and keepalives.
Default value: 1 (enabled)
The number of initial segments to send during congestion window negotiation.
Default value: 2 (segments)
Minimum value: 1
Maximum value: UINT_MAX, or 4 billion
A value that enables (0) or disables (1) window scaling.
Default value: 0 (enabled)
Note
The values for disabling and enabling are the reverse of what they are for most other attributes.
A value that enables (1) or disables (0) TCP keepalive for all sockets. TCP keepalive supports the periodic transmission of messages
on a connected socket in order to keep connections active. If keepalive is enabled, sockets that do not exit cleanly are cleaned up
when the keepalive interval expires. If keepalive is not enabled, those sockets will continue to exist until you reboot the sys-
tem.
Default value: 0 (disabled)
Applications enable keepalive for sockets by setting the setsockopt() function's SO_KEEPALIVE option. Use the tcp_keepalive_default
attribute to override programs that do not set keepalive on their own, particularly if you have no access to the sources for those
programs.
Maximum number of keepalive probes that can be sent before a connection is dropped.
Default value: TCPTV_KEEPCNT, or 8 (probes)
Minimum value: 1
Maximum value: 32767
Idle time before the first keepalive probe.
Default value: TCPTV_KEEP_IDLE, or 14400 (in units of .5 seconds)
Minimum value: 1
Maximum value: 32767
Initial connect timeout.
Default value: TCPTV_KEEP_INIT, or 150 (in units of .5 seconds)
Minimum value: 1
Maximum value: 32767
Time between keepalive probes.
Default value: TCPTV_KEEP_INTVL, or 150 (in units of .5 seconds)
Minimum value: 1
Maximum value: 32767
The maximum lifetime of a TCP segment.
Default value: 60 (in units of .5 seconds)
Minimum value: 1
Maximum value: 2 billion
Default maximum segment size.
Default value: TCP_MSS, or 536 (bytes)
Minimum value: 1
Maximum value: 2 billion
Default receive buffer size for TCP sockets.
Default value: TCP_RECVSPACE, or 61440 (bytes)
Minimum value: 1
Maximum value: 4 billion (cannot be larger than sb_max)
Minimum amount of time between TCP retransmissions.
Default value: 2 (in units of .5 seconds), or 1 second
Minimum value: 1
Maximum value: 2 billion
The maximum number of TCP retransmitted packets to send before giving up.
Default value: 128 (packets)
Minimum value: 1
Maximum value: INT_MAX, or 2 billion
Initial assumed round-trip time, in seconds.
Default value: 3 (seconds)
Minimum value: 0
Maximum value: INT_MAX, or 2 billion
Default send buffer size, in bytes, for TCP sockets.
Default value: TCP_SENDSPACE, or 61440 (bytes)
Minimum value: 1
Maximum value: UINT_MAX, or 4 billion (cannot be larger than sb_max)
IP time-to-live, in router hops, for TCP packets.
Default value: TCP_TTL, or 60 (router hops)
Minimum value: 0
Maximum value: 255
A value that enables (1) or disables (0) 4.2 BSD-compatible behavior for an urgent pointer. The urgent pointer is a pointer to the
first octet of data past the urgent section. When disabled, the urgent pointer is a pointer to the last octet of data in the urgent
section.
Default value: 1 (enabled)
A value that enables (0) or disables (1) delayed acknowledgments.
Default value: 0 (enabled)
Note
The values for disabling and enabling are the reverse of what they are for most other attributes.
Number of duplicate acknowledgments (ACKs) before retransmission.
Default value: TCPREXMTTHRESH, or 3 (duplicate acknowledgements)
Minimum value: 1
Maximum value: INT_MAX, or 2 billion
A value that enables (1) or disables (0) the movement of TCP inpcbs in the TIME_WAIT state to the end of the inpcb list.
Default value: 0 (disabled)
Default receive buffer size, in bytes, for UDP sockets.
Default value: UDP_RECVSPACE, or 42240 (bytes)
Minimum value: 1
Maximum value: UINT_MAX, or 4 billion (cannot be larger than sb_max)
Default send buffer size, in bytes, for UDP sockets.
Default value: UDP_SENDSPACE, or 9216 (bytes)
Minimum value: 1
Maximum value: UINT_MAX, or 4 billion (cannot be larger than sb_max)
IP time-to-live, in router hops, for UDP packets.
Default value: UDP_TTL, or 30 (router hops)
Minimum value: 0
Maximum value: 255
A value that enables (1) or disables (0) checksumming in the Internet user datagram protocol (UDP).
Default value: 1 (enabled)
SEE ALSO
sys_attrs(5)
Tuning Tru64 UNIX for Internet Servers at the following location: http://www.digital.com/internet/document/ias/tuning.html.
System Configuration and Tuning
sys_attrs_inet(5)