On Wed, 2013-01-16 at 14:22 -0500, Mike Frysinger wrote: Hi, Mike, Please take a look at my first email in this thread. The user application includes <linux/if_bridge.h> and <netinet/in.h>. <linux/if_bridge.h> uses struct_in6 but doesn't include <linux/in6.h> (this is my bad, sorry), an obvious fix is just including <linux/in6.h>. But this immediately breaks applications which include <linux/if_bridge.h> and <netinet/in.h>, just as what Thomas reported. And if_bridge.h is kernel-specific, there is no corresponding glibc one, so you can't blame applications which include both of them. Thanks.