svcadm(8)을 검색하려면 섹션에서 8 을 선택하고, 맨 페이지 이름에 svcadm을 입력하고 검색을 누른다.
sctp(4)
The protocol provides reliable, flow-controlled, two-way trans‐
mission of data. It is a message oriented protocol and can sup‐
port the and abstractions. uses the standard Internet address
format and, in addition, provides a per-host collection of Thus,
each address is composed of an Internet address specifying the
host and network, with a specific port on the host identifying
the peer entity. There are two models of programming in SCTP.
The first uses the abstraction. In this abstraction sockets uti‐
lizing the protocol are either or Active sockets initiate connec‐
tions to passive sockets. By default, sockets are created ac‐
tive; to create a passive socket, the system call must be used
after binding the socket with the or system calls. Only passive
sockets may use the call to accept incoming connections. Only
active sockets may use the call to initiate connections. The
other abstraction provides a mode of operation in that the user
may send to an address (using any of the valid send calls that
carry a socket address) and an association will be setup implic‐
itly by the underlying transport stack. This abstraction is the
only one capable of sending data on the third leg of the four-way
handshake. A user must still call to allow the socket to accept
connections. Calling however does not restrict the user from
still initiating implicit connections to other peers. The proto‐
col directly supports multi-homing. So when binding a socket
with the address the stack will inform the peer about all of the
local addresses that are deemed in scope of the peer. The peer
will then possibly have multiple paths to reach the local host.
The transport protocol is also multi-streamed. Multi-streaming
refers to the ability to send sub-ordered flows of messages. A
user performs this by specifying a specific stream in one of the
extended send calls such as the function call. Sending messages
on different streams will allow parallel delivery of data i.e., a
message loss in stream 1 will not block the delivery of messages
sent in stream 2. The transport protocol also provides a un‐
ordered service as well. The unordered service allows a message
to be sent and delivered with no regard to the ordering of any
other message. The FreeBSD implementation of also supports the
following extensions: This extension allows one to have message
be skipped and not delivered based on some user specified parame‐
ters. This extension allows addresses to be added and deleted
dynamically from an existing association. This extension allows
the user to authenticate specific peer chunks (including data) to
validate that the peer who sent the message is in fact the peer
who setup the association. A shared key option is also provided
for so that two stacks can pre-share keys. Some routers support
a special satellite protocol that will report losses due to cor‐
ruption. This allows retransmissions without subsequent loss in
bandwidth utilization. This extension allows a user on either
side to reset the stream sequence numbers used by any or all
streams. supports a number of socket options which can be set
with and tested with or Under most circumstances, sends data when
it is presented; when outstanding data has not yet been acknowl‐
edged, it gathers small amounts of output to be sent in a single
packet once an acknowledgement is received. For some clients,
such as window systems that send a stream of mouse events which
receive no replies, this packetization may cause significant de‐
lays. The boolean option defeats this algorithm. This option
returns specific information about an associations It can also be
used to change the default values. This option returns specific
information about the requested association. This option allows
you to get or set the default sending parameters when an associa‐
tion is implicitly setup. It allows you to change such things as
the maximum number of streams allowed inbound and the number of
streams requested of the peer. For the one-to-many model associ‐
ations are setup implicitly. This option allows the user to
specify a default number of idle seconds to allow the association
be maintained. After the idle timer (where no user message have
been sent or have been received from the peer) the association
will be gracefully closed. The default for this value is 0, or
unlimited (i.e., no automatic close). The dynamic address exten‐
sion allows a peer to also request a particular address of its be
made into the primary address. This option allows the caller to
make such a request to a peer. Note that if the peer does not
also support the dynamic address extension, this call will fail.
Note the caller must provide a valid local address that the peer
has been told about during association setup or dynamically.
This option allows the setting of the primary address that the
caller wishes to send to. The caller provides the address of a
peer that is to be made primary. The dynamic address extension
also allows a user to pass a 32 bit opaque value upon association
setup. This option allows a user to set or get this value. By
default will fragment user messages into multiple pieces that
will fit on the network and then later, upon reception, reassem‐
ble the pieces into a single user message. If this option is en‐
abled instead, any send that exceeds the path maximum transfer
unit (P-MTU) will fail and the message will NOT be sent. This
option will allow a user to set or get specific peer address pa‐
rameters. When a user does not use one of the extended send
calls (e.g., a set of default values apply to each send. These
values include things like the stream number to send to as well
as the per-protocol id. This option lets a caller both get and
set these values. If the user changes these default values, then
these new values will be used as the default whenever no informa‐
tion is provided by the sender (i.e., the non-extended API is
used). has non-data events that it can communicate to its appli‐
cation. By default these are all disabled since they arrive in
the data path with a special flag set upon the received message.
This option lets a caller both get what events are current being
received as well as set different events that they may be inter‐
ested in receiving. supports both IPV4 and IPV6. An association
may span both IPV4 and IPV6 addresses since is multi-homed. By
default, when opening an IPV6 socket, when data arrives on the
socket from a peer's V4 address the V4 address will be presented
with an address family of AF_INET. If this is undesirable, then
this option can be enabled which will then convert all V4 ad‐
dresses into mapped V6 representations. By default chooses its
message fragmentation point based upon the smallest P-MTU of the
peer. This option lets the caller set it to a smaller value.
Note that while the user can change this value, if the P-MTU is
smaller than the value set by the user, then the P-MTU value will
override any user setting. This option lets the user both set
and get the delayed ack time (in milliseconds) that is using.
The default is 200 milliseconds. at times may need to start de‐
livery of a very large message before the entire message has ar‐
rived. By default SCTP waits until the incoming message is
larger than one fourth of the receive buffer. This option allows
the stacks value to be overridden with a smaller value. at times
will start partial delivery (as mentioned above). In the normal
case successive reads will continue to return the rest of the
message, blocking if needed, until all of that message is read.
However this means other messages may have arrived and be ready
for delivery and be blocked behind the message being partially
delivered. If this option is enabled, when a partial delivery
message has no more data to be received, then a subsequent read
may return a different message that is ready for delivery. By
default this option is off since the user must be using the ex‐
tended API's to be able to tell the difference between messages
(via the stream and stream sequence number). By default only the
dynamic addressing chunks are authenticated. This option lets a
user request an additional chunk be authenticated as well. Note
that successive calls to this option will work and continue to
add more chunks that require authentication. Note that this op‐
tion only effects future associations and not existing ones.
This option allows a user to specify a shared key that can be
later used to authenticate a peer. This option will let you get
or set the list of HMAC algorithms used to authenticate peers.
Note that the HMAC values are in priority order where the first
HMAC identifier is the most preferred and the last is the least
preferred. This option allows you to make a key active for the
generation of authentication information. Note that the peer
must have the same key or else the data will be discarded. This
option allows you to delete an old key. The sockets api document
allows an extended send/receive information structure to be used.
The extended structure includes additional fields related to the
next message to be received (after the current receive completes)
if such information is known. By default the system will not
pass this information. This option allows the user to request
this information. By default when bound to all address and the
system administrator has enables automatic dynamic addresses, the
stack will automatically generate address changes into add and
delete requests to any peers by setting this option to true.
This option allows an endpoint to disable that behavior. By de‐
fault implements micro-burst control so that as the congestion
window opens up no large burst of packets can be generated. The
default burst limit is four. This option lets the user change
this value. Many sctp extended calls have a context field. The
context field is a 32 bit opaque value that will be returned in
send failures. This option lets the caller set the default con‐
text value to use when none is provided by the user. By default,
a single send is a complete message. generates an implied record
boundary. If this option is enabled, then all sends are part of
the same message until the user indicates an end of record with
the special flag passed in the sctp_sndrcvinfo flags field. This
effectively makes all sends part of the same message until the
user specifies differently. This means that a caller must NOT
change the stream number until after the is passed to else an er‐
ror will be returned. This option is a read-only option that re‐
turns various status information about the specified association.
This read-only option returns information about a peer address.
This read-only option returns a list of the chunks the peer re‐
quires to be authenticated. This read-only option returns a list
of the locally required chunks that must be authenticated. This
socket option is used to cause a stream sequence number or all
stream sequence numbers to be reset. Note that the peer endpoint
must also support the stream reset extension as well. The proto‐
col implements a number of variables in the branch of the MIB.
Default congestion control module. Default value is 0. The min‐
imum is 0, and the maximum is 3. A value of 0 enables the de‐
fault congestion control algorithm. A value of 1 enables the
High Speed congestion control algorithm. A value of 2 enables
the HTCP congestion control algorithm. A value of 3 enables the
data center congestion control (DCCC) algorithm. Defines the
initial congestion window size in MTUs. Use congestion control
instead of 'blind' logic to limit maximum burst when sending.
Default value is 1. May be set to 0 or 1. Enable Explicit Con‐
gestion Notification (ECN). Default value is 1. May be set to 0
or 1. Number of identical bandwidth measurements DCCC takes to
try step down the congestion window. Default value is 20. The
minimum is 0, and the maximum is 65535. Whether DCCC reduces the
congestion window size when round-trip time and bandwidth remain
unchanged. Default value is 0. May be set to 0 or 1. Shift
amount DCCC uses for bandwidth smoothing on round-trip-time cal‐
culation. Default value is 4. The minimum is 0, and the maximum
is 32. Shift amount DCCC uses for round-trip-time smoothing on
round-trip-time calculation. Default value is 5. The minimum is
0, and the maximum is 32. Enable ECN when using DCCC. Default
value is 1. May be set to 0 or 1. Get the ucred of a SCTP con‐
nection. List of active SCTP associations. SCTP statistics
(struct sctp_stat). Diagnostic information error cause code.
Enable SCTP blackholing. See for more details. Enable send/re‐
ceive buffer splitting. Vtag wait time in seconds, 0 to disable.
Enable sending of the NAT-friendly SCTP option on INITs. Enable
sending of the SACK-IMMEDIATELY bit. Set the SCTP/UDP tunneling
port. Enable SCTP fast handoff. Enable SCTP base mobility De‐
fault fragment interleave level. Default stream scheduling mod‐
ule. Ltrace/KTR trace logging level. Number of retransmissions
of a DATA chunk before an association is aborted. Minimum resid‐
ual data chunk in second part of split. Enforce strict data or‐
dering, abort if control inside data. Abort when one-to-one hits
qlimit. Confirmation heartbeat max burst. Flush chunks in re‐
ceive queues with TSN higher than the cumulative TSN if the sys‐
tem is low on mbufs. Default max number of small mbufs on a
chain. SCTP ABC max increase per SACK (L). SCTP NAT friendly
operation. CMT DAC on/off flag. CMT settings. Default number
of outgoing streams. Default number of incoming streams. When
space-wise is it worthwhile to try to add more to a socket send
buffer. Default potentially failed threshold. Default maximum
of retransmissions per path. Default maximum number of retrans‐
missions per association. Default maximum number of retransmis‐
sions for INIT chunks. Default cookie lifetime in seconds. De‐
fault maximum retransmission timeout during association setup in
ms. Default initial retransmission timeout in ms. Default mini‐
mum retransmission timeout in ms. Default maximum retransmission
timeout in ms. Default secret lifetime in seconds. Shutdown
guard timer in seconds (0 means 5 times RTO.Max). Default PMTU
raise timer in seconds. Default heartbeat interval in ms. Max
number of cached resources in an association. Max number of
cached resources in the system. Default SACK frequency. Default
delayed SACK timer in ms. Tunable for scaling of number of
chunks and messages. Minimum size when splitting a chunk. Tun‐
able for PCB hash table sizes. Tunable for TCB hash table sizes.
Default max chunks on queue per association. Default max burst
for SCTP endpoints when fast retransmitting. Default max burst
for SCTP endpoints. Amount to debit peers rwnd per chunk sent.
Enable SCTP Strict SACK checking. Enable SCTP PKTDROP. Enable
SCTP NR-SACK. Enable SCTP RE-CONFIG. Enable SCTP ASCONF. En‐
able SCTP AUTH. Enable PR-SCTP. Enable SCTP Auto-ASCONF. Maxi‐
mum incoming SCTP buffer size. Maximum outgoing SCTP buffer
size.