Credentials passing, HOWTO

• SO_PASSCRED enables sending of credentials.

• For connected SOCK_STREAM sockets: use the SO_PEERCRED getsockopt.

• For SOCK_DGRAM the senders can send an SCM_CREDENTIALS control message with the datagram. It contains pid/uid/gid

• Sender sets its own values, but kernel checks them. Root can override it. If client sends nothing the kernel fills in defaults.