# udplite(7) - man - phpMan [UDPLITE(7)](https://www.chedong.com/phpMan.php/man/UDPLITE/7/markdown) Linux Programmer's Manual [UDPLITE(7)](https://www.chedong.com/phpMan.php/man/UDPLITE/7/markdown) ## NAME udplite - Lightweight User Datagram Protocol ## SYNOPSIS ### #include **sockfd** **=** **socket(AF**___**INET,** **SOCK**___**DGRAM,** **IPPROTO**___**UDPLITE);** ## DESCRIPTION This is an implementation of the Lightweight User Datagram Protocol (UDP-Lite), as described in RFC 3828. UDP-Lite is an extension of UDP (RFC 768) to support variable-length checksums. This has ad‐ vantages for some types of multimedia transport that may be able to make use of slightly dam‐ aged datagrams, rather than having them discarded by lower-layer protocols. The variable-length checksum coverage is set via a [**setsockopt**(2)](https://www.chedong.com/phpMan.php/man/setsockopt/2/markdown) option. If this option is not set, the only difference from UDP is in using a different IP protocol identifier (IANA number 136). The UDP-Lite implementation is a full extension of [**udp**(7)](https://www.chedong.com/phpMan.php/man/udp/7/markdown)—that is, it shares the same API and API behavior, and in addition offers two socket options to control the checksum coverage. ### Address format UDP-Litev4 uses the _sockaddr_in_ address format described in [**ip**(7)](https://www.chedong.com/phpMan.php/man/ip/7/markdown). UDP-Litev6 uses the _sock__‐ _addr_in6_ address format described in [**ipv6**(7)](https://www.chedong.com/phpMan.php/man/ipv6/7/markdown). ### Socket options To set or get a UDP-Lite socket option, call [**getsockopt**(2)](https://www.chedong.com/phpMan.php/man/getsockopt/2/markdown) to read or [**setsockopt**(2)](https://www.chedong.com/phpMan.php/man/setsockopt/2/markdown) to write the option with the option level argument set to **IPPROTO**___**UDPLITE**. In addition, all **IP**‐‐ **PROTO**___**UDP** socket options are valid on a UDP-Lite socket. See [**udp**(7)](https://www.chedong.com/phpMan.php/man/udp/7/markdown) for more information. The following two options are specific to UDP-Lite. **UDPLITE**___**SEND**___**CSCOV** This option sets the sender checksum coverage and takes an _int_ as argument, with a checksum coverage value in the range 0..2^16-1. A value of 0 means that the entire datagram is always covered. Values from 1-7 are illegal (RFC 3828, 3.1) and are rounded up to the minimum coverage of 8. With regard to IPv6 jumbograms (RFC 2675), the UDP-Litev6 checksum coverage is limited to the first 2^16-1 octets, as per RFC 3828, 3.5. Higher values are therefore silently truncated to 2^16-1. If in doubt, the current coverage value can always be queried using [**getsockopt**(2)](https://www.chedong.com/phpMan.php/man/getsockopt/2/markdown). **UDPLITE**___**RECV**___**CSCOV** This is the receiver-side analogue and uses the same argument format and value range as **UDPLITE**___**SEND**___**CSCOV**. This option is not required to enable traffic with partial checksum coverage. Its function is that of a traffic filter: when enabled, it in‐ structs the kernel to drop all packets which have a coverage _less_ than the specified coverage value. When the value of **UDPLITE**___**RECV**___**CSCOV** exceeds the actual packet coverage, incoming packets are silently dropped, but may generate a warning message in the system log. ## ERRORS All errors documented for [**udp**(7)](https://www.chedong.com/phpMan.php/man/udp/7/markdown) may be returned. UDP-Lite does not add further errors. ## FILES _/proc/net/snmp_ Basic UDP-Litev4 statistics counters. _/proc/net/snmp6_ Basic UDP-Litev6 statistics counters. ## VERSIONS UDP-Litev4/v6 first appeared in Linux 2.6.20. ## BUGS Where glibc support is missing, the following definitions are needed: #define IPPROTO_UDPLITE 136 #define UDPLITE_SEND_CSCOV 10 #define UDPLITE_RECV_CSCOV 11 ## SEE ALSO [**ip**(7)](https://www.chedong.com/phpMan.php/man/ip/7/markdown), [**ipv6**(7)](https://www.chedong.com/phpMan.php/man/ipv6/7/markdown), [**socket**(7)](https://www.chedong.com/phpMan.php/man/socket/7/markdown), [**udp**(7)](https://www.chedong.com/phpMan.php/man/udp/7/markdown) RFC 3828 for the Lightweight User Datagram Protocol (UDP-Lite). _Documentation/networking/udplite.txt_ in the Linux kernel source tree ## COLOPHON This page is part of release 5.10 of the Linux _man-pages_ project. A description of the project, information about reporting bugs, and the latest version of this page, can be found at . Linux 2017-09-15 [UDPLITE(7)](https://www.chedong.com/phpMan.php/man/UDPLITE/7/markdown)