By the manual page you mentioned: http://linux.die.net/man/7/socket
> SO_SNDBUF: [...] The default value is set by the wmem_default sysctl and the maximum allowed value is set by the wmem_max sysctl.
You can't use sysctl under OpenVZ. QED.
> SO_SNDBUF: [...] The default value is set by the wmem_default sysctl and the maximum allowed value is set by the wmem_max sysctl.
You can't use sysctl under OpenVZ. QED.