Socket::Constants

Socket::Constants provides socket-related constants. All possible socket constants are listed in the documentation but they may not all be present on your platform.

If the underlying platform doesn't define a constant the corresponding Ruby constant is not defined.

Constants

AF_ALG: Interface to kernel crypto API
AF_APPLETALK: AppleTalk protocol
AF_ATM: Asynchronous Transfer Mode
AF_AX25: AX.25 protocol
AF_BLUETOOTH: Bluetooth low-level socket protocol
AF_CAN: Controller Area Network automotive bus protocol
AF_CCITT: CCITT (now ITU-T) protocols
AF_CHAOS: MIT CHAOS protocols
AF_CNT: Computer Network Technology
AF_COIP: Connection-oriented IP
AF_DATAKIT: Datakit protocol
AF_DEC: DECnet protocol
AF_DECnet: DECnet protocol
AF_DLI: DEC Direct Data Link Interface protocol
AF_E164: CCITT (ITU-T) E.164 recommendation
AF_ECMA: European Computer Manufacturers protocols
AF_HYLINK: NSC Hyperchannel protocol
AF_IB: InfiniBand native addressing
AF_IMPLINK: ARPANET IMP protocol
AF_INET: IPv4 protocol
AF_INET6: IPv6 protocol
AF_IPX: IPX protocol
AF_ISDN: Integrated Services Digital Network
AF_ISO: ISO Open Systems Interconnection protocols
AF_KCM: KCM (kernel connection multiplexor) interface
AF_KEY: Key management protocol, originally developed for usage with IPsec
AF_LAT: Local Area Transport protocol
AF_LINK: Link layer interface
AF_LLC: Logical link control (IEEE 802.2 LLC) protocol
AF_LOCAL: Host-internal protocols
AF_MAX: Maximum address family for this platform
AF_MPLS: Multiprotocol Label Switching
AF_NATM: Native ATM access
AF_NDRV: Network driver raw access
AF_NETBIOS: NetBIOS
AF_NETGRAPH: Netgraph sockets
AF_NETLINK: Kernel user interface device
AF_NS: XEROX NS protocols
AF_OSI: ISO Open Systems Interconnection protocols
AF_PACKET: Direct link-layer access
AF_PPP: Point-to-Point Protocol
AF_PPPOX: Generic PPP transport layer, for setting up L2 tunnels (L2TP and PPPoE)
AF_PUP: PARC Universal Packet protocol
AF_RDS: Reliable Datagram Sockets (RDS) protocol
AF_ROUTE: Internal routing protocol
AF_SIP: Simple Internet Protocol
AF_SNA: IBM SNA protocol
AF_SYSTEM
AF_TIPC: TIPC, “cluster domain sockets” protocol
AF_UNIX: UNIX sockets
AF_UNSPEC: Unspecified protocol, any supported address family
AF_VSOCK: VSOCK (originally “VMWare VSockets”) protocol for hypervisor-guest communication
AF_XDP: XDP (express data path) interface
AI_ADDRCONFIG: Accept only if any address is assigned
AI_ALL: Allow all addresses
AI_CANONNAME: Fill in the canonical name
AI_DEFAULT: Default flags for getaddrinfo
AI_MASK: Valid flag mask for getaddrinfo (not for application use)
AI_NUMERICHOST: Prevent host name resolution
AI_NUMERICSERV: Prevent service name resolution
AI_PASSIVE: Get address to use with bind()
AI_V4MAPPED: Accept IPv4-mapped IPv6 addresses
AI_V4MAPPED_CFG: Accept IPv4 mapped addresses if the kernel supports it
EAI_ADDRFAMILY: Address family for hostname not supported
EAI_AGAIN: Temporary failure in name resolution
EAI_BADFLAGS: Invalid flags
EAI_BADHINTS: Invalid value for hints
EAI_FAIL: Non-recoverable failure in name resolution
EAI_FAMILY: Address family not supported
EAI_MAX: Maximum error code from getaddrinfo
EAI_MEMORY: Memory allocation failure
EAI_NODATA: No address associated with hostname
EAI_NONAME: Hostname nor servname, or not known
EAI_OVERFLOW: Argument buffer overflow
EAI_PROTOCOL: Resolved protocol is unknown
EAI_SERVICE: Servname not supported for socket type
EAI_SOCKTYPE: Socket type not supported
EAI_SYSTEM: System error returned in errno
IFF_802_1Q_VLAN: 802.1Q VLAN device
IFF_ALLMULTI: receive all multicast packets
IFF_ALTPHYS: use alternate physical connection
IFF_AUTOMEDIA: auto media select active
IFF_BONDING: bonding master or slave
IFF_BRIDGE_PORT: device used as bridge port
IFF_BROADCAST: broadcast address valid
IFF_CANTCHANGE: flags not changeable
IFF_CANTCONFIG: unconfigurable using ioctl(2)
IFF_DEBUG: turn on debugging
IFF_DISABLE_NETPOLL: disable netpoll at run-time
IFF_DONT_BRIDGE: disallow bridging this ether dev
IFF_DORMANT: driver signals dormant
IFF_DRV_OACTIVE: tx hardware queue is full
IFF_DRV_RUNNING: resources allocated
IFF_DYING: interface is winding down
IFF_DYNAMIC: dialup device with changing addresses
IFF_EBRIDGE: ethernet bridging device
IFF_ECHO: echo sent packets
IFF_ISATAP: ISATAP interface (RFC4214)
IFF_LINK0: per link layer defined bit 0
IFF_LINK1: per link layer defined bit 1
IFF_LINK2: per link layer defined bit 2
IFF_LIVE_ADDR_CHANGE: hardware address change when it's running
IFF_LOOPBACK: loopback net
IFF_LOWER_UP: driver signals L1 up
IFF_MACVLAN_PORT: device used as macvlan port
IFF_MASTER: master of a load balancer
IFF_MASTER_8023AD: bonding master, 802.3ad.
IFF_MASTER_ALB: bonding master, balance-alb.
IFF_MASTER_ARPMON: bonding master, ARP mon in use
IFF_MONITOR: user-requested monitor mode
IFF_MULTICAST: supports multicast
IFF_NOARP: no address resolution protocol
IFF_NOTRAILERS: avoid use of trailers
IFF_OACTIVE: transmission in progress
IFF_OVS_DATAPATH: device used as Open vSwitch datapath port
IFF_POINTOPOINT: point-to-point link
IFF_PORTSEL: can set media type
IFF_PPROMISC: user-requested promisc mode
IFF_PROMISC: receive all packets
IFF_RENAMING: interface is being renamed
IFF_ROUTE: routing entry installed
IFF_RUNNING: resources allocated
IFF_SIMPLEX: can't hear own transmissions
IFF_SLAVE: slave of a load balancer
IFF_SLAVE_INACTIVE: bonding slave not the curr. active
IFF_SLAVE_NEEDARP: need ARPs for validation
IFF_SMART: interface manages own routes
IFF_STATICARP: static ARP
IFF_SUPP_NOFCS: sending custom FCS
IFF_TEAM_PORT: used as team port
IFF_TX_SKB_SHARING: sharing skbs on transmit
IFF_UNICAST_FLT: unicast filtering
IFF_UP: interface is up
IFF_VOLATILE: volatile flags
IFF_WAN_HDLC: WAN HDLC device
IFF_XMIT_DST_RELEASE: dev_hard_start_xmit() is allowed to release skb->dst
IFNAMSIZ: Maximum interface name size
IF_NAMESIZE: Maximum interface name size
INADDR_ALLHOSTS_GROUP: Multicast group for all systems on this subset
INADDR_ANY: A socket bound to INADDR_ANY receives packets from all interfaces and sends from the default IP address
INADDR_BROADCAST: The network broadcast address
INADDR_LOOPBACK: The loopback address
INADDR_MAX_LOCAL_GROUP: The last local network multicast group
INADDR_NONE: A bitmask for matching no valid IP address
INADDR_UNSPEC_GROUP: The reserved multicast group
INET6_ADDRSTRLEN: Maximum length of an IPv6 address string
INET_ADDRSTRLEN: Maximum length of an IPv4 address string
IPPORT_RESERVED: Default minimum address for bind or connect
IPPORT_USERRESERVED: Default maximum address for bind or connect
IPPROTO_AH: IP6 auth header
IPPROTO_BIP
IPPROTO_DSTOPTS: IP6 destination option
IPPROTO_EGP: Exterior Gateway Protocol
IPPROTO_EON: ISO cnlp
IPPROTO_ESP: IP6 Encapsulated Security Payload
IPPROTO_FRAGMENT: IP6 fragmentation header
IPPROTO_GGP: Gateway to Gateway Protocol
IPPROTO_HELLO: “hello” routing protocol
IPPROTO_HOPOPTS: IP6 hop-by-hop options
IPPROTO_ICMP: Control message protocol
IPPROTO_ICMPV6: ICMP6
IPPROTO_IDP: XNS IDP
IPPROTO_IGMP: Group Management Protocol
IPPROTO_IP: Dummy protocol for IP
IPPROTO_IPV6: IP6 header
IPPROTO_MAX: Maximum IPPROTO constant
IPPROTO_ND: Sun net disk protocol
IPPROTO_NONE: IP6 no next header
IPPROTO_PUP: PARC Universal Packet protocol
IPPROTO_RAW: Raw IP packet
IPPROTO_ROUTING: IP6 routing header
IPPROTO_TCP: TCP
IPPROTO_TP: ISO transport protocol class 4
IPPROTO_UDP: UDP
IPPROTO_XTP: Xpress Transport Protocol
IPV6_CHECKSUM: Checksum offset for raw sockets
IPV6_DONTFRAG: Don't fragment packets
IPV6_DSTOPTS: Destination option
IPV6_HOPLIMIT: Hop limit
IPV6_HOPOPTS: Hop-by-hop option
IPV6_JOIN_GROUP: Join a group membership
IPV6_LEAVE_GROUP: Leave a group membership
IPV6_MULTICAST_HOPS: IP6 multicast hops
IPV6_MULTICAST_IF: IP6 multicast interface
IPV6_MULTICAST_LOOP: IP6 multicast loopback
IPV6_NEXTHOP: Next hop address
IPV6_PATHMTU: Retrieve current path MTU
IPV6_PKTINFO: Receive packet information with datagram
IPV6_RECVDSTOPTS: Receive all IP6 options for response
IPV6_RECVHOPLIMIT: Receive hop limit with datagram
IPV6_RECVHOPOPTS: Receive hop-by-hop options
IPV6_RECVPATHMTU: Receive current path MTU with datagram
IPV6_RECVPKTINFO: Receive destination IP address and incoming interface
IPV6_RECVRTHDR: Receive routing header
IPV6_RECVTCLASS: Receive traffic class
IPV6_RTHDR: Allows removal of sticky routing headers
IPV6_RTHDRDSTOPTS: Allows removal of sticky destination options header
IPV6_RTHDR_TYPE_0: Routing header type 0
IPV6_TCLASS: Specify the traffic class
IPV6_UNICAST_HOPS: IP6 unicast hops
IPV6_USE_MIN_MTU: Use the minimum MTU size
IPV6_V6ONLY: Only bind IPv6 with a wildcard bind
IPX_TYPE
IP_ADD_MEMBERSHIP: Add a multicast group membership
IP_ADD_SOURCE_MEMBERSHIP: Add a multicast group membership
IP_BLOCK_SOURCE: Block IPv4 multicast packets with a give source address
IP_DEFAULT_MULTICAST_LOOP: Default multicast loopback
IP_DEFAULT_MULTICAST_TTL: Default multicast TTL
IP_DONTFRAG: Don't fragment packets
IP_DROP_MEMBERSHIP: Drop a multicast group membership
IP_DROP_SOURCE_MEMBERSHIP: Drop a multicast group membership
IP_FREEBIND: Allow binding to nonexistent IP addresses
IP_HDRINCL: Header is included with data
IP_IPSEC_POLICY: IPsec security policy
IP_MAX_MEMBERSHIPS: Maximum number multicast groups a socket can join
IP_MINTTL: Minimum TTL allowed for received packets
IP_MSFILTER: Multicast source filtering
IP_MTU: The Maximum Transmission Unit of the socket
IP_MTU_DISCOVER: Path MTU discovery
IP_MULTICAST_IF: IP multicast interface
IP_MULTICAST_LOOP: IP multicast loopback
IP_MULTICAST_TTL: IP multicast TTL
IP_ONESBCAST: Force outgoing broadcast datagrams to have the undirected broadcast address
IP_OPTIONS: IP options to be included in packets
IP_PASSSEC: Retrieve security context with datagram
IP_PKTINFO: Receive packet information with datagrams
IP_PKTOPTIONS: Receive packet options with datagrams
IP_PMTUDISC_DO: Always send DF frames
IP_PMTUDISC_DONT: Never send DF frames
IP_PMTUDISC_WANT: Use per-route hints
IP_PORTRANGE: Set the port range for sockets with unspecified port numbers
IP_RECVDSTADDR: Receive IP destination address with datagram
IP_RECVERR: Enable extended reliable error message passing
IP_RECVIF: Receive interface information with datagrams
IP_RECVOPTS: Receive all IP options with datagram
IP_RECVRETOPTS: Receive all IP options for response
IP_RECVSLLA: Receive link-layer address with datagrams
IP_RECVTOS: Receive TOS with incoming packets
IP_RECVTTL: Receive IP TTL with datagrams
IP_RETOPTS: IP options to be included in datagrams
IP_ROUTER_ALERT: Notify transit routers to more closely examine the contents of an IP packet
IP_SENDSRCADDR: Source address for outgoing UDP datagrams
IP_TOS: IP type-of-service
IP_TRANSPARENT: Transparent proxy
IP_TTL: IP time-to-live
IP_UNBLOCK_SOURCE: Unblock IPv4 multicast packets with a give source address
IP_XFRM_POLICY
LOCAL_CONNWAIT: Connect blocks until accepted
LOCAL_CREDS: Pass credentials to receiver
LOCAL_PEERCRED: Retrieve peer credentials
MCAST_BLOCK_SOURCE: Block multicast packets from this source
MCAST_EXCLUDE: Exclusive multicast source filter
MCAST_INCLUDE: Inclusive multicast source filter
MCAST_JOIN_GROUP: Join a multicast group
MCAST_JOIN_SOURCE_GROUP: Join a multicast source group
MCAST_LEAVE_GROUP: Leave a multicast group
MCAST_LEAVE_SOURCE_GROUP: Leave a multicast source group
MCAST_MSFILTER: Multicast source filtering
MCAST_UNBLOCK_SOURCE: Unblock multicast packets from this source
MSG_COMPAT: End of record
MSG_CONFIRM: Confirm path validity
MSG_CTRUNC: Control data lost before delivery
MSG_DONTROUTE: Send without using the routing tables
MSG_DONTWAIT: This message should be non-blocking
MSG_EOF: Data completes connection
MSG_EOR: Data completes record
MSG_ERRQUEUE: Fetch message from error queue
MSG_FASTOPEN: Reduce step of the handshake process
MSG_FIN
MSG_FLUSH: Start of a hold sequence. Dumps to so_temp
MSG_HAVEMORE: Data ready to be read
MSG_HOLD: Hold fragment in so_temp
MSG_MORE: Sender will send more
MSG_NOSIGNAL: Do not generate SIGPIPE
MSG_OOB: Process out-of-band data
MSG_PEEK: Peek at incoming message
MSG_PROXY: Wait for full request
MSG_RCVMORE: Data remains in the current packet
MSG_RST
MSG_SEND: Send the packet in so_temp
MSG_SYN
MSG_TRUNC: Data discarded before delivery
MSG_WAITALL: Wait for full request or error
NI_DGRAM: The service specified is a datagram service (looks up UDP ports)
NI_MAXHOST: Maximum length of a hostname
NI_MAXSERV: Maximum length of a service name
NI_NAMEREQD: A name is required
NI_NOFQDN: An FQDN is not required for local hosts, return only the local part
NI_NUMERICHOST: Return a numeric address
NI_NUMERICSERV: Return the service name as a digit string
PF_ALG: Interface to kernel crypto API
PF_APPLETALK: AppleTalk protocol
PF_ATM: Asynchronous Transfer Mode
PF_AX25: AX.25 protocol
PF_BLUETOOTH: Bluetooth low-level socket protocol
PF_CAN: Controller Area Network automotive bus protocol
PF_CCITT: CCITT (now ITU-T) protocols
PF_CHAOS: MIT CHAOS protocols
PF_CNT: Computer Network Technology
PF_COIP: Connection-oriented IP
PF_DATAKIT: Datakit protocol
PF_DEC: DECnet protocol
PF_DECnet: DECnet protocol
PF_DLI: DEC Direct Data Link Interface protocol
PF_ECMA: European Computer Manufacturers protocols
PF_HYLINK: NSC Hyperchannel protocol
PF_IB: InfiniBand native addressing
PF_IMPLINK: ARPANET IMP protocol
PF_INET: IPv4 protocol
PF_INET6: IPv6 protocol
PF_IPX: IPX protocol
PF_ISDN: Integrated Services Digital Network
PF_ISO: ISO Open Systems Interconnection protocols
PF_KCM: KCM (kernel connection multiplexor) interface
PF_KEY: Key management protocol, originally developed for usage with IPsec
PF_LAT: Local Area Transport protocol
PF_LINK: Link layer interface
PF_LLC: Logical link control (IEEE 802.2 LLC) protocol
PF_LOCAL: Host-internal protocols
PF_MAX: Maximum address family for this platform
PF_MPLS: Multiprotocol Label Switching
PF_NATM: Native ATM access
PF_NDRV: Network driver raw access
PF_NETBIOS: NetBIOS
PF_NETGRAPH: Netgraph sockets
PF_NETLINK: Kernel user interface device
PF_NS: XEROX NS protocols
PF_OSI: ISO Open Systems Interconnection protocols
PF_PACKET: Direct link-layer access
PF_PIP
PF_PPP: Point-to-Point Protocol
PF_PPPOX: Generic PPP transport layer, for setting up L2 tunnels (L2TP and PPPoE)
PF_PUP: PARC Universal Packet protocol
PF_RDS: Reliable Datagram Sockets (RDS) protocol
PF_ROUTE: Internal routing protocol
PF_RTIP
PF_SIP: Simple Internet Protocol
PF_SNA: IBM SNA protocol
PF_SYSTEM
PF_TIPC: TIPC, “cluster domain sockets” protocol
PF_UNIX: UNIX sockets
PF_UNSPEC: Unspecified protocol, any supported address family
PF_VSOCK: VSOCK (originally “VMWare VSockets”) protocol for hypervisor-guest communication
PF_XDP: XDP (express data path) interface
PF_XTP: eXpress Transfer Protocol
SCM_BINTIME: Timestamp (bintime)
SCM_CREDENTIALS: The sender's credentials
SCM_CREDS: Process credentials
SCM_RIGHTS: Access rights
SCM_TIMESTAMP: Timestamp (timeval)
SCM_TIMESTAMPING: Timestamp (timespec list) (Linux 2.6.30)
SCM_TIMESTAMPNS: Timespec (timespec)
SCM_UCRED: User credentials
SCM_WIFI_STATUS: Wifi status (Linux 3.3)
SHUT_RD: Shut down the reading side of the socket
SHUT_RDWR: Shut down the both sides of the socket
SHUT_WR: Shut down the writing side of the socket
SOCK_CLOEXEC: Set the close-on-exec (FD_CLOEXEC) flag on the new file descriptor.
SOCK_DGRAM: A datagram socket provides connectionless, unreliable messaging
SOCK_NONBLOCK: Set the O_NONBLOCK file status flag on the open file description (see open(2)) referred to by the new file descriptor.
SOCK_PACKET: Device-level packet access
SOCK_RAW: A raw socket provides low-level access for direct access or implementing network protocols
SOCK_RDM: A reliable datagram socket provides reliable delivery of messages
SOCK_SEQPACKET: A sequential packet socket provides sequenced, reliable two-way connection for datagrams
SOCK_STREAM: A stream socket provides a sequenced, reliable two-way connection for a byte stream
SOL_ATALK: AppleTalk socket options
SOL_AX25: AX.25 socket options
SOL_IP: IP socket options
SOL_IPX: IPX socket options
SOL_SOCKET: Socket-level options
SOL_TCP: TCP socket options
SOL_UDP: UDP socket options
SOMAXCONN: Maximum connection requests that may be queued for a socket
SOPRI_BACKGROUND: Background socket priority
SOPRI_INTERACTIVE: Interactive socket priority
SOPRI_NORMAL: Normal socket priority
SO_ACCEPTCONN: Socket has had listen() called on it
SO_ACCEPTFILTER: There is an accept filter
SO_ALLZONES: Bypass zone boundaries
SO_ATTACH_FILTER: Attach an accept filter
SO_BINDTODEVICE: Only send packets from the given interface
SO_BINTIME: Receive timestamp with datagrams (bintime)
SO_BPF_EXTENSIONS: Query supported BPF extensions (Linux 3.14)
SO_BROADCAST: Permit sending of broadcast messages
SO_BUSY_POLL: Set the threshold in microseconds for low latency polling (Linux 3.11)
SO_DEBUG: Debug info recording
SO_DETACH_FILTER: Detach an accept filter
SO_DOMAIN: Domain given for socket() (Linux 2.6.32)
SO_DONTROUTE: Use interface addresses
SO_DONTTRUNC: Retain unread data
SO_ERROR: Get and clear the error status
SO_GET_FILTER: Obtain filter set by SO_ATTACH_FILTER (Linux 3.8)
SO_KEEPALIVE: Keep connections alive
SO_LINGER: Linger on close if data is present
SO_LOCK_FILTER: Lock the filter attached to a socket (Linux 3.9)
SO_MAC_EXEMPT: Mandatory Access Control exemption for unlabeled peers
SO_MARK: Set the mark for mark-based routing (Linux 2.6.25)
SO_MAX_PACING_RATE: Cap the rate computed by transport layer. [bytes per second] (Linux 3.13)
SO_NKE: Install socket-level Network Kernel Extension
SO_NOFCS: Set netns of a socket (Linux 3.4)
SO_NOSIGPIPE: Don't SIGPIPE on EPIPE
SO_NO_CHECK: Disable checksums
SO_NREAD: Get first packet byte count
SO_OOBINLINE: Leave received out-of-band data in-line
SO_PASSCRED: Receive SCM_CREDENTIALS messages
SO_PASSSEC: Toggle security context passing (Linux 2.6.18)
SO_PEEK_OFF: Set the peek offset (Linux 3.4)
SO_PEERCRED: The credentials of the foreign process connected to this socket
SO_PEERNAME: Name of the connecting user
SO_PEERSEC: Obtain the security credentials (Linux 2.6.2)
SO_PRIORITY: The protocol-defined priority for all packets on this socket
SO_PROTOCOL: Protocol given for socket() (Linux 2.6.32)
SO_RCVBUF: Receive buffer size
SO_RCVBUFFORCE: Receive buffer size without rmem_max limit (Linux 2.6.14)
SO_RCVLOWAT: Receive low-water mark
SO_RCVTIMEO: Receive timeout
SO_RECVUCRED: Receive user credentials with datagram
SO_REUSEADDR: Allow local address reuse
SO_REUSEPORT: Allow local address and port reuse
SO_RXQ_OVFL: Toggle cmsg for number of packets dropped (Linux 2.6.33)
SO_SECURITY_AUTHENTICATION
SO_SECURITY_ENCRYPTION_NETWORK
SO_SECURITY_ENCRYPTION_TRANSPORT
SO_SELECT_ERR_QUEUE: Make select() detect socket error queue with errorfds (Linux 3.10)
SO_SNDBUF: Send buffer size
SO_SNDBUFFORCE: Send buffer size without wmem_max limit (Linux 2.6.14)
SO_SNDLOWAT: Send low-water mark
SO_SNDTIMEO: Send timeout
SO_TIMESTAMP: Receive timestamp with datagrams (timeval)
SO_TIMESTAMPING: Time stamping of incoming and outgoing packets (Linux 2.6.30)
SO_TIMESTAMPNS: Receive nanosecond timestamp with datagrams (timespec)
SO_TYPE: Get the socket type
SO_USELOOPBACK: Bypass hardware when possible
SO_WANTMORE: Give a hint when more data is ready
SO_WANTOOBFLAG: OOB data is wanted in MSG_FLAG on receive
SO_WIFI_STATUS: Toggle cmsg for wifi status (Linux 3.3)
TCP_CONGESTION: TCP congestion control algorithm (Linux 2.6.13, glibc 2.6)
TCP_COOKIE_TRANSACTIONS: TCP Cookie Transactions (Linux 2.6.33, glibc 2.18)
TCP_CORK: Don't send partial frames (Linux 2.2, glibc 2.2)
TCP_DEFER_ACCEPT: Don't notify a listening socket until data is ready (Linux 2.4, glibc 2.2)
TCP_FASTOPEN: Reduce step of the handshake process (Linux 3.7, glibc 2.18)
TCP_INFO: Retrieve information about this socket (Linux 2.4, glibc 2.2)
TCP_KEEPCNT: Maximum number of keepalive probes allowed before dropping a connection (Linux 2.4, glibc 2.2)
TCP_KEEPIDLE: Idle time before keepalive probes are sent (Linux 2.4, glibc 2.2)
TCP_KEEPINTVL: Time between keepalive probes (Linux 2.4, glibc 2.2)
TCP_LINGER2: Lifetime of orphaned FIN_WAIT2 sockets (Linux 2.4, glibc 2.2)
TCP_MAXSEG: Set maximum segment size
TCP_MD5SIG: Use MD5 digests (RFC2385, Linux 2.6.20, glibc 2.7)
TCP_NODELAY: Don't delay sending to coalesce packets
TCP_NOOPT: Don't use TCP options
TCP_NOPUSH: Don't push the last block of write
TCP_QUEUE_SEQ: Sequence of a queue for repair mode (Linux 3.5, glibc 2.18)
TCP_QUICKACK: Enable quickack mode (Linux 2.4.4, glibc 2.3)
TCP_REPAIR: Repair mode (Linux 3.5, glibc 2.18)
TCP_REPAIR_OPTIONS: Options for repair mode (Linux 3.5, glibc 2.18)
TCP_REPAIR_QUEUE: Queue for repair mode (Linux 3.5, glibc 2.18)
TCP_SYNCNT: Number of SYN retransmits before a connection is dropped (Linux 2.4, glibc 2.2)
TCP_THIN_DUPACK: Duplicated acknowledgments handling for thin-streams (Linux 2.6.34, glibc 2.18)
TCP_THIN_LINEAR_TIMEOUTS: Linear timeouts for thin-streams (Linux 2.6.34, glibc 2.18)
TCP_TIMESTAMP: TCP timestamp (Linux 3.9, glibc 2.18)
TCP_USER_TIMEOUT: Max timeout before a TCP connection is aborted (Linux 2.6.37, glibc 2.18)
TCP_WINDOW_CLAMP: Clamp the size of the advertised window (Linux 2.4, glibc 2.2)
UDP_CORK: Don't send partial frames (Linux 2.5.44, glibc 2.11)