Hi, small bug in net-server.c code. Note: the kdc.conf has kdc_tcp_ports = "" to disable tcp . On startup krb5kdc logs: Jul 27 16:12:38 myhostname krb5kdc[26223](info): setting up network... Jul 27 16:12:38 myhostname krb5kdc[26223](info): listening on fd 7: udp 0.0.0.0.88 (pktinfo) krb5kdc: Address family not supported by protocol - Cannot create TCP server socket on ::.88 Jul 27 16:12:38 myhostname krb5kdc[26223](info): set up 1 sockets Jul 27 16:12:38 myhostname krb5kdc[26226](info): commencing operation strace shows a call to socket to match the "::.88" log entry: socket(PF_INET6, SOCK_DGRAM, IPPROTO_IP) = -1 EAFNOSUPPORT (Address family not supported by protocol) write(3, "krb5kdc: Address family not supp"..., 93) = 93 I think this may be showing a small bug in lib/apputils/net-server.c. 1. The log message should show UDP not TCP as a UDP socket is being attempted to be created. The code logs TCP always regardless of whether UDP or TCP socket is being created. This is confusing in the situation above where tcp has been disabled in kdc.conf. -- David Shrimpton Information Technology Services | The University of Queensland