Tthe FTP service uses RFC 931 for user identification, which isn’t supported in Mac OS X (why we’ll move on to other FTP servers in the future). To resolve, add the -I option in the xinetd configuration as you see here: service ftp { disable = no instances = 100 socket_type = stream wait = no user = root server = /usr/libexec/xftpd server_args = -aI groups = yes }