| Datatype | Description | Header |
| int8_t | Signed 8-bit integer (char) | <sys/types.h> |
| uint8_t | Unsigned 8-bit integer (unsigned char) | <sys/types.h> |
| int16_t | Signed 16-bit integer (short) | <sys/types.h> |
| uint16_t | Unsigned 16-bit integer (unsigned short) | <sys/types.h> |
| int32_t | Signed 32-bit integer (int) | <sys/types.h> |
| uint32_t | Unsigned 32-bit integer (unsigned int) | <sys/types.h> |
| sa_family_t | Address family of socket address struct | <sys/types.h> |
| socklen_t | Length of socket address struct (unint32_t) | <sys/types.h> |
| in_addr_t | IPv4 address (uint32_t) | <netinet/in.h> |
| in_port_t | TCP or UDP port (uint16_t) | <netinet/in.h> |
| u_char | Unsigned char - OBSOLETE | |
| u_short | Unsigned short - OBSOLETE | |
| u_int | Unsigned int - OBSOLETE | |
| u_long | Unsigned long - OBSOLETE | |
| struct timeval | long tv_sec (secs), long tv_usec (microsecs) | <sys/time.h> |