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sys_attrs_inet(5)					    sys_attrs_inet(5)
Patchkit 6							   Patchkit 6



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 introduc-
  tion to the topic of kernel subsystem	attributes.



  icmp_redirecttimeout
      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



  inifaddr_hsize
      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



  ipdefttl
      The default Internet Protocol (IP) time-to-live value.

      Default value: DEFTTL, or	64 (router hops)

      Minimum value: 0

      Maximum value: 255



  ipdirected_broadcast
      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 broad-
      cast address.

      Default value: 0 (disabled)



  ipforwarding
      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.



  ipfragttl
      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



  ipgateway
      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.



  ipport_userreserved
      The number of times a system can simultaneously make outgoing connec-
      tions 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



  ipport_userreserved_min
      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



  ipqmaxlen
      Maximum length of	the IP input queue (ipintrq) before input packets are
      dropped.

      Default value: 1024 (bytes)

      Minimum value: 1024

      Maximum value: 65535



  ipqs
      Maximum number of	IP input queues.

      Default value: 1 (queues)

      Minimum value: 1

      Maximum value: 64



  ipsendredirects
      A	value that enables (1) or disables (0) the sending of ICMP redirect
      messages.

      Default value: 1 (enabled)



  ipsrcroute
      Enables (1) or disables (0) source routing.

      Default value: 1 (enabled)



  pmtu_decrease_intvl
      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



  pmtu_enabled
      A	value that enables (1) or disables (0) discovery of the	path maximum
      transfer unit (PMTU).

      Default value: 1 (enabled)



  pmtu_increase_intvl
      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



  pmtu_rt_check_intvl
      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



  subnetsarelocal
      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)



  tcbhashnum
      The number of Transmission Control Protocol (TCP)	hash tables.

      Default value: 1 (table)

      Minimum value: 1

      Maximum value: 64



  tcbhashsize
      The number of buckets in the TCP inpcb hash table.

      Default value: 512 (buckets)

      Minimum value: 0

      Maximum value: INT_MAX, or 2 billion



  tcbquicklisten
      Enables (1) or disables (0) optimization of the listen path for server
      sockets.

      Default value: 1 (enabled)



  tcp_compat_42
      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)



  tcp_cwnd_segments
      The number of initial segments to	send during congestion window nego-
      tiation.

      Default value: 2 (segments)

      Minimum value: 1

      Maximum value: INT_MAX, or 2 billion



  tcp_dont_winscale
      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.



  tcp_keepalive_default
      A	value that enables (1) or disables (0) TCP keepalive for all sockets.
      TCP keepalive supports the periodic transmission of messages on a	con-
      nected 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 sock-
      ets 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 attri-
      bute to override programs	that do	not set	keepalive on their own,	par-
      ticularly	if you have no access to the sources for those programs.



  tcp_keepcnt
      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



  tcp_keepidle
      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



  tcp_keepinit
      Initial connect timeout.

      Default value: TCPTV_KEEP_INIT, or 150 (in units of .5 seconds)

      Minimum value: 2

      Maximum value: 32767



  tcp_keepintvl
      Time between keepalive probes.

      Default value: TCPTV_KEEP_INTVL, or 150 (in units	of .5 seconds)

      Minimum value: 2

      Maximum value: 32767



  tcp_msl
      The maximum lifetime of a	TCP segment.

      Default value: 60	(in units of .5	seconds)

      Minimum value: 1

      Maximum value: 2 billion



  tcp_mssdflt
      Default maximum segment size.

      Default value: TCP_MSS, or 536 (bytes)

      Minimum value: 1

      Maximum value: 2 billion



  tcp_recvspace
      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)



  tcp_rexmit_interval_min
      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



  tcp_rexmtmax
      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



  tcp_rttdflt
      Initial assumed round-trip time, in seconds.

      Default value: 3 (seconds)

      Minimum value: 0

      Maximum value: INT_MAX, or 2 billion



  tcp_sendspace
      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)



  tcp_ttl
      IP time-to-live, in router hops, for TCP packets.

      Default value: TCP_TTL, or 128 (router hops)

      Minimum value: 0

      Maximum value: 255



  tcp_urgent_42
      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)



  tcpnodelack
      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.



  tcprexmtthresh
      Number of	duplicate acknowledgments (ACKs) before	retransmission.

      Default value: TCPREXMTTHRESH, or	3 (duplicate acknowledgements)

      Minimum value: 1

      Maximum value: INT_MAX, or 2 billion



  tcptwreorder
      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)



  udp_recvspace
      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)



  udp_sendspace
      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)



  udp_ttl
      IP time-to-live, in router hops, for UDP packets.

      Default value: UDP_TTL, or 128 (router hops)

      Minimum value: 0

      Maximum value: 255



  udpcksum
      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