xti_sctp.3.man

This a separate release of the OpenSS7 X/Open XTI/TLI library, TLI modules (timod, tirdwr) and the I

RTO (Retransmission Time Out) value when sending packets.
This option if formatted as a
.BR t_scalar_t .
Value values are
zero or greater and must be less than or equal to the value
.IR T_SCTP_RTO_MAX .
To be effective, this option must be set with the call to
.BR t_connect "(3) or before the call to " t_listen (3),
or when a passive connection indication is accepted with
.BR t_accept (3).
Active destinations can be controlled with the option
.IR T_SCTP_RTO ,
below.
.\"
.\"
.TP
.B T_SCTP_RTO_MAX
Determine the time interval (in milliseconds) that will be used as a maximum
RTO (Retransmission Time Out) value when sending packets.
This option if formatted as a
.BR t_scalar_t .
Value values are
zero or greater and must be greater than or equal to the value
.IR T_SCTP_RTO_MIN .
To be effective, this option must be set with the call to
.BR t_connect "(3) or before the call to " t_listen (3),
or when a passive connection indication is accepted with
.BR t_accept (3).
Active destinations can be controlled with the option
.IR T_SCTP_RTO ,
below.
.\"
.\"
.TP
.B T_SCTP_PATH_MAX_RETRANS
This option determines the number of times that the sending endpoint will
attempt retransmitting a packet to a given destination transport address before
it considers that destination transport address inactive.  This option is
formatted as a
.BR t_scalar_t .
Value values include zero.
This options is used with
.BR t_optmgmt "(3), " t_connect "(3) or " t_accept (3).
.sp
The value set with
.BR t_optmgmt (3)
is the value that will be assigned to new destinations.
To be effective, this option must be set with the call to
.BR t_connect "(3) or before the call to " t_listen (3),
or when a passive connection indication is accepted with
.BR t_accept (3).
Active destinations can be controlled with the option
.IR T_SCTP_RTO ,
below.
.\"
.\"
.TP
.B T_SCTP_RTO
This option determines the retransmission timeout parameters associated with a
specific destination address.
The option value is formatted as a
.B t_sctp_rto
structure, formatted as follows:
.sp
.nf
\fC\s-1\
typedef struct t_sctp_rto {
    uint32_t rto_dest;       /* destination address */
    t_uscalar_t rto_initial; /* RTO.Initial (millisec) */
    t_uscalar_t rto_min;     /* RTO.Min (millisec) */
    t_uscalar_t rto_max;     /* RTO.Max (millisec) */
    t_uscalar_t max_retrans; /* Path.Max.Retrans (retries) */
} t_sctp_rto_t;
\s+1\fR
.fi
.sp
The
.B t_sctp_rto
structure has the following fields:
.RS
.TP \w'max_retrans\(em'u
.I rto_dest
is a
.B sockaddr_in
structure that contains the destination address to which the rto parameter
settings apply.
.PD 0
.TP
.I rto_initial
is the
.B t_uscalar_t
initial retransmission timeout value in milliseconds.  For valid values, see
.IR T_SCTP_RTO_INITIAL .
.TP
.I rto_min
is the
.B t_uscalar_t
minimum retransmission timeout value in milliseconds.  For valid values, see
.IR T_SCTP_RTO_MIN .
.TP
.I rto_max
is the
.B t_uscalar_t
maximum retransmission timeout value in milliseconds.  For valid values, see
.IR T_SCTP_RTO_MAX .
.TP
.I max_retrans
is the
.B t_uscalar_t
maximum number of retransmissions.  For valid values, see
.IR T_SCTP_PATH_MAX_RETRANS .
.PD
.PP
For use with
.BR t_optmgmt (3),
.I dest
must be one of the valid destination addresses associated with the transport
connection.
.RE
.\"
.\"
.TP
.B T_SCTP_CKSUM_TYPE
This option determines the checksum type that will be used to checksum SCTP
packets.
The option value is formatted as a
.BR t_scalar_t ,
and can have on of the following values:
.RS
.TP
.I T_SCTP_CSUM_ADLER_32
use the older RFC 2960
.[
RFC 2960
.]
Adler 32 checksum to checksum SCTP packets.
.TP
.I T_SCTP_CSUM_CRC_32C
use the newer RFC 3309
.[
RFC 3309
.]
CRC32 checksum to checksum SCTP packets.
.PP
To be effective, this option must be set with the call to
.BR t_connect "(3) or before the call to " t_listen (3),
or when a passive connection indication is accepted with
.BR t_accept (3).
.RE
.\"
.\"
.TP
.B T_SCTP_MAC_TYPE
This option determines the MAC (Message Authentication Code) type that will be
used with signing cookies in INIT-ACK messages.
The option value is formatted as a
.BR t_scalar_t ,
and can have one of the following values:
.RS
.TP
.I T_SCTP_HMAC_NONE
No message authentication code will be used.  The MAC field will be populated
with all ones.  This completely disables the MAC features of
.BR SCTP ,
and should be used with caution.
.TP
.I T_SCTP_HMAC_SHA_1
The message authentication code will use SHA-1 message digest.
.TP
.I T_SCTP_HMAC_MD5
The message authentication code will use MD5 message digest.
.PP
To be effective, this option must be set before the call to
.BR t_listen (3),
or when a passive connection indication is accepted with
.BR t_accept (3).
The option can be read at any time and reflects the current setting.
.RE
.\"
.\"
.TP
.B T_SCTP_COOKIE_LIFE
Determines the cookie lifetime associated with a transport endpoint.  This is
the amount of time that cookies sent to the peer endpoint in an INIT-ACK
message will be valid.  For
.B SCTP
this also limits the maximum for which the HMAC secret key for the cookie will
be valid.  The option value is formatted as a
.B t_scalar_t
that contains the time interval in milliseconds.  Valid values are zero (0) or
greater.  The default value is that proscribed by RFC 2960.
.[
RFC 2960
.]
This options is used with
.BR t_optmgmt "(3), " t_connect "(3) or " t_accept (3).
.sp
The value set with
.BR t_optmgmt (3)
is the value assigned to the transport endpoint.
To be effective, this option must be set with the call to
.BR t_connect "(3) or before the call to " t_listen (3),
or when a passive connection indication is accepted with
.BR t_accept (3).
.sp
Reducing this value will increase the changes that passive connection attempts
will fail due to expired cookies.  Increasing the value will reduce the
overall security of the system by permitting attackers an increased interval
to crack HMACs and guess verification tags.  This value may be adjusted in
conjunction with the
.I T_SCTP_COOKIE_INC
to meet most objected for successful passive connection attempts with the best
security afforded by smaller values of
.IR T_SCTP_COOKIE_LIFE .
.sp
Unfortunately the
.IR T_SCTP_COOKIE_LIFE " and " T_SCTP_COOKIE_INC
must be adjusted to accommodate the slowest peer on the slowest connection.
The default setting is adequate for Internet applications.
.\"
.\"
.TP
.B T_SCTP_COOKIE_INC
This option determines the time increment (in milliseconds) that will be added
to the lifespan of the cookie in an INIT-ACK if the sender of the INIT
requested cookie preservation to lengthen the lifespan of the cookie.
The option value is formatted as a
.BR t_scalar_t .
Valid values include zero.
To be effective, this option must be set before the call to
.BR t_listen (3),
or when a passive connection indication is accepted with
.BR t_accept (3).
The option can be read at any time and reflects the current setting.
.\"
.\"
.TP
.B T_SCTP_THROTTLE_ITVL
Determines the interval (in milliseconds) within which the receiver will not
accept more than one INIT or COOKIE-ECHO.
The option value is formatted as a
.BR t_scalar_t .
Zero (don't throttle) is a valid value.
To be effective, this option must be set before the call to
.BR t_listen (3),
or when a passive connection indication is accepted with
.BR t_accept (3).
The option can be read at any time and reflects the current setting.
.\"
.\"
.TP
.B T_SCTP_ISTREAMS
Sets the maximum number of inbound streams or gets the actual number of
inbound streams associated with the transport connection.
The option value is formatted as a
.BR t_scalar_t .
Valid values are from 1 to 16,736.
To be effective, this option must be set with the call to
.BR t_connect "(3) or before the call to " t_listen (3),
or when a passive connection indication is accepted with
.BR t_accept (3).
For active transport connections, setting this option has no effect on the
current transport connection.
.\"
.\"
.TP
.B T_SCTP_OSTREAMS
Sets the maximum number of outbound streams or gets the actual number of
outbound streams associated with the transport connection.
The option value is formatted as a
.BR t_scalar_t .
Valid values are from 1 to 16,736.
To be effective, this option must be set with the call to
.BR t_connect "(3) or before the call to " t_listen (3),
or when a passive connection indication is accepted with
.BR t_accept (3).
For active transport connections, setting this option has no effect on the
current transport connection.
.\"
.\"
.TP
.B T_SCTP_SSN
This option determines the SCTP Stream Sequence Number that is to be associated
with a given data transmission.  The option value is formatted as a
.B t_scalar_t
that contains the numeric value of the SCTP Stream Sequence Number.  This options
is used with
.BR t_optmgmt (3).
The SCTP transport provider determines which values will be used on all packets sent with
.BR t_snd "(3), " t_sndv "(3), " write "(2) or " writev (2).
The current value, when read, using
.BR t_optmgmt (3),
will return the value that was contained in the last packet read with
.BR t_rcv "(3), " t_rcvv "(3), " read "(2) or " readv (2).
.\"
.\"
.TP
.B T_SCTP_ECN
This option determines whether the Explicit Congestion Notification (ECN)
capability of RFC 3168
.[
RFC 3168
.]
and Appendix A of RFC 2960
.[
RFC 2960
.]
is used on the transport connection.
The option value is formatted as a
.B t_scalar_t
and have have valid values
.BR T_YES " or " T_NO .
.sp
When set to
.BR T_YES ,
explicit congestion notification is enabled on the transport connection.
When set to
.BR T_NO ,
explicit congestion notification is disabled on the transport connection.
To be effective, this option must be set with the call to
.BR t_connect "(3) or before the call to " t_listen (3),
or when a passive connection indication is accepted with
.BR t_accept (3).
For active transport connections, setting this option has no effect on the
current transport connection.
.\"
.\"
.TP
.B T_SCTP_ALI
This option determines the adaptation layer information
(described in draft-ietf-tsvwg-addip-sctp-07.txt)
.[
draft-ietf-tsvwg-addip-sctp-07.txt
.]
to be used in the INIT
or INIT-ACK on all passive or active connection attempts on the transport
endpoint, or gets the adaptation layer information provided by the transport
peer on a connected transport endpoint.
The option value is formatted as a
.B t_scalar_t
that contains the adaptation layer information.
.sp
When set to zero (0), no adaptation layer information will be included in the
INIT or INIT-ACK; when non-zero, it contains the flag bits that will be sent
in the adaptation layer information in the INIT or INIT-ACK.
To be effective, this option must be set with the call to
.BR t_connect "(3) or before the call to " t_listen (3),
or when a passive connection indication is accepted with
.BR t_accept (3).
.sp
If the transport endpoint is in a disconnected state (and has never been
connected), getting this option returns zero (0).  If the transport endpoint
has been in a connected state, getting this option returns zero (0) if no
adaptation layer information was present during the connection, or returns
the adaptation layer information bits if provided by the peer.
.sp
This option supports the adaptation layer information features described in
draft-ietf-tsvwg-addip-sctp-07.txt.
.[
draft-ietf-tsvwg-addip-sctp-07.txt
.]
.\"
.\"
.TP
.B T_SCTP_PR
This option determines whether partial reliability (described in
draft-ietf-tsvwg-prsctp-00.txt)
.[
draft-ietf-tsvwg-prsctp-00.txt
.]
will be supported or required on transport connection establishment, or gets
the indication of support for partial reliability provided by the peer on a
connected transport endpoint.
The option value is formatted as a
.B t_scalar_t
and can contain one of the following values:
.RS
.TP
.I T_SCTP_PR_NONE
do not place or response with a Forward TSN parameter in an INIT or INIT-ACK
indicating to the peer that we do not support partial reliability for this
transport connection.
.TP
.I T_SCTP_PR_PREFERRED
place and response with a Forward TSN parameter in an INIT or INIT-ACK
indicating to the peer that we support partial reliability, but do no require
the peer to support partial reliability.
.TP
.I T_SCTP_PR_REQUIRED
place and response with a Forward TSN parameter in an INIT or INIT-ACK
indicating to the peer that we support partial reliability and require the
peer to do the same.
.PP
For a connected transport endpoint, when this options is set to
.BR T_SCTP_PR_PREFERRED " or " T_SCTP_PR_REQUIRED ,
it indicates that the peer supports partial reliability.  When set to
.BR T_SCTP_PR_NONE ,
it indicates that the peer does not support partial reliability.
.RE
.\"
.\"
.TP
.B T_SCTP_MAX_INIT_RETRIES
This option determines the number of times that an INIT or COOKIE-ECHO will be
resent before abandoning the transport connection initialization.
This option value is formatted as a
.BR t_scalar_t .
To be effective, this option must be set with the call to
.BR t_connect "(3) or before the call to " t_listen (3),
or when a passive connection indication is accepted with
.BR t_accept (3).
.\"
.\"
.TP
.B T_SCTP_MAX_BURST
This option determines the number of MTUs of data that will be sent in a
single burst, as defined in
draft-ietf-tsvwg-sctpimpguide-08.txt.
.[
draft-ietf-tsvwg-sctpimpguide-08.txt
.]
The option value is formatted as a
.BR t_scalar_t .
Valid values are one (1) or greater.  This option may be changed at any time
during the transport connection lifetime.  This option is of local
significance only.
.\"
.\"
.TP
.B T_SCTP_ASSOC_MAX_RETRANS
Determines the number of times that the sending endpoint will attempt
retransmitting a packet on a given transport connection before it aborts the
connection.
This option is formatted as a
.BR t_scalar_t .
Value values include zero.  This value should be larger than the sum of all
the
.I T_SCTP_PATH_MAX_RETRANS
values of each of the destinations.  This option may be changed on the stream
at any time during the life of the transport connection.
.\"
.\"
.TP
.B T_SCTP_SACK_DELAY
This option determines the maximum SACK delay as the interval of time (in
milliseconds) that the sending endpoint will delay an acknowledgment of a
received DATA chunk.
The option value is formatted as a
.BR t_scalar_t .
Valid values are zero (0) or greater, however, the maximum SACK delay should
not exceed 500 milliseconds (setting this value to greater than 500
milliseconds is forbidden by RFC 2960)
.[
RFC 2960
.]
for Internet Applications.
This option may be changed at any time during the life of the transport