---
name: "IP_UNBLOCK_SOURCE"
section: "2const"
platform: "linux"
package: "man-pages"
version: "6.19-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/IP_UNBLOCK_SOURCE"
---

# IP\_UNBLOCK\_SOURCE(2const)

unblock multicast source

## NAME

IP\_UNBLOCK\_SOURCE - unblock multicast source

## LIBRARY

Standard C library (*libc*, *-lc*)

## SYNOPSIS

```
#include <netinet/in.h>  /* Definition of IP* constants */
#include <sys/socket.h>
```

**int setsockopt(int** *sockfd***, IPPROTO\_IP, IP\_UNBLOCK\_SOURCE,**                **const struct ip\_mreq\_source \****src***,**                **sizeof(struct ip\_mreq\_source));**

## DESCRIPTION

Unblock previously blocked multicast source.

Fails with **EADDRNOTAVAIL** when given source is not being blocked.

## ERRORS

See [**IPPROTO\_IP**(2const)](/IPPROTO_IP/2const.md). See [**setsockopt**(2)](/setsockopt/2.md). See [**ip**(7)](/ip/7.md).

## HISTORY

Linux 2.4.22, Linux 2.5.68.

## SEE ALSO

[**IPPROTO\_IP**(2const)](/IPPROTO_IP/2const.md), [**setsockopt**(2)](/setsockopt/2.md), [**ip**(7)](/ip/7.md)