---
name: "udplite"
section: "7"
platform: "linux"
package: "man-pages"
version: "6.19-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/udplite"
---

# udplite(7)

Lightweight User Datagram Protocol

## NAME

udplite - Lightweight User Datagram Protocol

## SYNOPSIS

```
#include <sys/socket.h>
```

**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 advantages for some types of multimedia transport that may be able to make use of slightly damaged datagrams, rather than having them discarded by lower-layer protocols.

The variable-length checksum coverage is set via a [**setsockopt**(2)](/setsockopt/2.md) 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)](/udp/7.md)—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)](/ip/7.md). UDP-Litev6 uses the *sockaddr\_in6* address format described in [**ipv6**(7)](/ipv6/7.md).

### Socket options

To set or get a UDP-Lite socket option, call [**getsockopt**(2)](/getsockopt/2.md) to read or [**setsockopt**(2)](/setsockopt/2.md) to write the option with the option level argument set to **IPPROTO\_UDPLITE**. In addition, all **IPPROTO\_UDP** socket options are valid on a UDP-Lite socket. See [**udp**(7)](/udp/7.md) 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)](/getsockopt/2.md).

- **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 instructs 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)](/udp/7.md) 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)](/ip/7.md), [**ipv6**(7)](/ipv6/7.md), [**socket**(7)](/socket/7.md), [**udp**(7)](/udp/7.md)

RFC 3828 for the Lightweight User Datagram Protocol (UDP-Lite).

*Documentation/networking/udplite.rst* in the Linux kernel source tree