Module sockopt

Socket options as used by setsockopt and getsockopt.

Structs

AcceptConn

Returns a value indicating whether or not this socket has been marked to accept connections with listen(2).

AlgSetAeadAuthSize

AlgSetKey

BindToDevice

Bind this socket to a particular device like “eth0”.

Broadcast

Set or get the broadcast flag.

DontRoute

Set or get the don’t route flag.

Ip6tOriginalDst

IpAddMembership

Join a multicast group

IpBindAddressNoPort

If enabled, the kernel will not reserve an ephemeral port when binding socket with a port number of 0. The port will later be automatically chosen at connect time, in a way that allows sharing a source port as long as the 4-tuple is unique.

IpDropMembership

Leave a multicast group.

IpFreebind

If enabled, this boolean option allows binding to an IP address that is nonlocal or does not (yet) exist.

IpMtu

Fetch the current system-estimated Path MTU.

IpMulticastLoop

Set or read a boolean integer argument that determines whether sent multicast packets should be looped back to the local sockets.

IpMulticastTtl

Set or read the time-to-live value of outgoing multicast packets for this socket.

IpTos

Set or receive the Type-Of-Service (TOS) field that is sent with every IP packet originating from this socket

IpTransparent

Setting this boolean option enables transparent proxying on this socket.

Ipv4OrigDstAddr

The recvmsg(2) call will return the destination IP address for a UDP datagram.

Ipv4PacketInfo

Pass an IP_PKTINFO ancillary message that contains a pktinfo structure that supplies some information about the incoming packet.

Ipv4RecvErr

Enable extended reliable error message passing.

Ipv4Ttl

Set or retrieve the current time-to-live field that is used in every packet sent from this socket.

Ipv6AddMembership

Join an IPv6 multicast group.

Ipv6DontFrag

Set “don’t fragment packet” flag on the IPv6 packet.

Ipv6DropMembership

Leave an IPv6 multicast group.

Ipv6MulticastHops

Set or read the hop limit value of outgoing IPv6 multicast packets for this socket.

Ipv6OrigDstAddr

The recvmsg(2) call will return the destination IP address for a UDP datagram.

Ipv6RecvErr

Control receiving of asynchronous error options.

Ipv6RecvPacketInfo

Set delivery of the IPV6_PKTINFO control message on incoming datagrams.

Ipv6TClass

Traffic class associated with outgoing packets

Ipv6Ttl

Set the unicast hop limit for the socket.

Ipv6V6Only

The socket is restricted to sending and receiving IPv6 packets only.

KeepAlive

Enable sending of keep-alive messages on connection-oriented sockets.

Linger

When enabled, a close(2) or shutdown(2) will not return until all queued messages for the socket have been successfully sent or the linger timeout has been reached.

Mark

Set the mark for each packet sent through this socket (similar to the netfilter MARK target but socket-based).

OobInline

If this option is enabled, out-of-band data is directly placed into the receive data stream.

OriginalDst

PassCred

Enable or disable the receiving of the SCM_CREDENTIALS control message.

PeerCredentials

Return the credentials of the foreign process connected to this socket.

Priority

Set the protocol-defined priority for all packets to be sent on this socket

RcvBuf

Sets or gets the maximum socket receive buffer in bytes.

RcvBufForce

Using this socket option, a privileged (CAP_NET_ADMIN) process can perform the same task as SO_RCVBUF, but the rmem_max limit can be overridden.

ReceiveTimeout

Specify the receiving timeout until reporting an error.

ReceiveTimestamp

Enable or disable the receiving of the SO_TIMESTAMP control message.

ReceiveTimestampns

Enable or disable the receiving of the SO_TIMESTAMPNS control message.

ReuseAddr

Enables local address reuse

ReusePort

Permits multiple AF_INET or AF_INET6 sockets to be bound to an identical socket address.

RxqOvfl

Indicates that an unsigned 32-bit value ancillary message (cmsg) should be attached to received skbs indicating the number of packets dropped by the socket since its creation.

SendTimeout

Specify the sending timeout until reporting an error.

SndBuf

Sets or gets the maximum socket send buffer in bytes.

SndBufForce

Using this socket option, a privileged (CAP_NET_ADMIN) process can perform the same task as SO_SNDBUF, but the wmem_max limit can be overridden.

SockType

Gets the socket type as an integer.

SocketError

Get and clear the pending socket error.

TcpCongestion

This option allows the caller to set the TCP congestion control algorithm to be used, on a per-socket basis.

TcpFastOpenConnect

Enables TCP Fast Open (RFC 7413) on a connecting socket. If a fast open cookie is not available (first attempt to connect), connect syscall will behave as usual, except for internally trying to solicit a cookie from remote peer. When cookie is available, the next connect syscall will immediately succeed without actually establishing TCP connection. The connection establishment will be defered till the next write or sendmsg syscalls on the socket, allowing TCP prtocol to establish connection and send data in the same packets. Note: calling read right after connect without write on the socket will cause the blocking socket to be blocked forever.

TcpKeepCount

The maximum number of keepalive probes TCP should send before dropping the connection.

TcpKeepIdle

The time (in seconds) the connection needs to remain idle before TCP starts sending keepalive probes

TcpKeepInterval

The time (in seconds) between individual keepalive probes.

TcpMaxSeg

The maximum segment size for outgoing TCP packets.

TcpNoDelay

Under most circumstances, TCP sends data when it is presented; when outstanding data has not yet been acknowledged, it gathers small amounts of output to be sent in a single packet once an acknowledgement is received. For a small number of clients, such as window systems that send a stream of mouse events which receive no replies, this packetization may cause significant delays. The boolean option TCP_NODELAY defeats this algorithm.

TcpRepair

TcpTlsRx

Set the Kernel TLS read parameters on the TCP socket.

TcpTlsTx

Set the Kernel TLS write parameters on the TCP socket.

TcpUlp

Set the Upper Layer Protocol (ULP) on the TCP socket.

TcpUserTimeout

Specifies the maximum amount of time in milliseconds that transmitted data may remain unacknowledged before TCP will forcibly close the corresponding connection

Timestamping

Specifies exact type of timestamping information collected by the kernel Further reading

TxTime

Configures the behavior of time-based transmission of packets, for use with the TxTime control message.

UdpGroSegment

UdpGsoSegment

Enums

TlsCryptoInfo

Value used with the TcpTlsTx and TcpTlsRx socket options.