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sys_attrs_inet(5)
Contents
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sys_attrs_inet - inet subsystem attributes
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 maximum amount of time that a route created by
an ICMP redirect can exist before it is removed
from the system's routing tables. The default value
of 0 means that entries will not be removed from
the routing table.
Default value: 0 (seconds)
Minimum value: 0
Maximum value: UINT_MAX, or 4 billion
A bit mask that designates the ICMP codes that the
system should reject. For example, to reject ICMP
redirects, you would set the mask bit position for
the ICMP_REDIRECT code (5), which is 2^5 (32) in
integer, or 0x20 in hexadecimal. Multiple masks can
be combined to reject more than one code. Code
definitions can be found in the
/usr/sys/include/netinet/ip_icmp.h file.
Default value: 0 (bits)
Minimum value: 0
Maximum value: 131072, or 0x2000 in hexadecimal
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 broadcast 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. You can also enable this
functionality 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 functionality 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 number of IP fragment reassembly queues.
Default value: IP_DEFAULT_FRAG_INDEX, or 64
(queues)
Minimum value: 1
Maximum value: USHRT_MAX, or 65535
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: 2048 (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 BSDcompatible
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: INT_MAX, or 2 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
system.
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: 2
Maximum value: 32767
Initial connect timeout.
Default value: TCPTV_KEEP_INIT, or 150 (in units of
.5 seconds)
Minimum value: 2
Maximum value: 32767
Time between keepalive probes.
Default value: TCPTV_KEEP_INTVL, or 150 (in units
of .5 seconds)
Minimum value: 2
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 amount of time between TCP retransmissions.
Default value: 128 (in units of .5 seconds), or 64
seconds
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 128 (router hops)
Minimum value: 0
Maximum value: 255
A value that enables (1) or disables (0) 4.2 BSDcompatible
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 128 (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)
sys_attrs(5)
Tuning Tru64 UNIX for Internet Servers at the following
location: http://www.digital.com/internet/docu-
ment/ias/tuning.html.
System Configuration and Tuning
sys_attrs_inet(5)
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