Maximum ancillary buffer size allowed per socket. Ancillary data is a sequence of struct cmsghdr structures with appended data. The default size is 10240 bytes.


This appears to have changed to 20480. (On both an up to date version of gentoo and CentOS)

That looks like a Gentoo or Centos specific modification. I just checked, and the latest Linus kernel (that would be 2.6.36 currently) still has 10240 as a default value. OS is Debian sid.