| Value | Meaning |
|---|---|
| TCP_NODELAY1 | Don't delay send to coalesce packets |
| TCP_MAXSEG2 | Set maximum segment size |
| TCP_CORK3 | Control sending of partial frames |
| TCP_KEEPIDLE4 | Start keeplives after this period |
| TCP_KEEPINTVL5 | Interval between keepalives |
| TCP_KEEPCNT6 | Number of keepalives before death |
| TCP_SYNCNT7 | Number of SYN retransmits |
| TCP_LINGER28 | Life time of orphaned FIN-WAIT-2 state |
| TCP_DEFER_ACCEPT9 | Wake up listener only when data arrive |
| TCP_WINDOW_CLAMP10 | Bound advertised window |
| TCP_INFO11 | Information about this connection. |
| TCP_QUICKACK12 | Bock/reenable quick ACKs. |
| TCP_CONGESTION13 | Congestion control algorithm. |
| TCP_MD5SIG14 | TCP MD5 Signature (RFC2385) |
| TCP_COOKIE_TRANSACTIONS15 | TCP Cookie Transactions |
| TCP_THIN_LINEAR_TIMEOUTS16 | Use linear timeouts for thin streams |
| TCP_THIN_DUPACK17 | Fast retrans. after 1 dupack |
| TCP_USER_TIMEOUT18 | How long for loss retry before timeout |
| TCP_REPAIR19 | TCP sock is under repair right now |
| TCP_REPAIR_QUEUE20 | Set TCP queue to repair |
| TCP_QUEUE_SEQ21 | Set sequence number of repaired queue. |
| TCP_REPAIR_OPTIONS22 | Repair TCP connection options |
| TCP_FASTOPEN23 | Enable FastOpen on listeners |
| TCP_TIMESTAMP24 | TCP time stamp |
| TCP_NOTSENT_LOWAT25 | Limit number of unsent bytes in write queue. |
| TCP_CC_INFO26 | Get Congestion Control (optional) info. |
| TCP_SAVE_SYN27 | Record SYN headers for new connections. |
| TCP_SAVED_SYN28 | Get SYN headers recorded for connection. |
User-settable options (used with setsockopt).