I'm using NetBSD-3.0BETA.

What is required to enable s/key authentication for sshd? The top
portion of my /etc/pam.d/sshd looks like this:

# auth
auth            required        pam_nologin.so  no_warn
auth            sufficient      pam_skey.so
auth            sufficient      pam_krb5.so     no_warn try_first_pass
# pam_ssh has potential security risks.  See pam_ssh(8).
#auth           sufficient      pam_ssh.so      no_warn try_first_pass
auth            required        pam_unix.so     no_warn try_first_pass

In /etc/ssh/sshd_config, ChallengeResponseAuthentication is explictly
set to yes (the man page states the default is yes).=20
PasswordAuthentication is set to no.

S/key should work:
$ skeyinfo
Your next otp-md4 98 anti74858

However:
$ ssh localhost
socket: Protocol not supported
Permission denied (publickey,keyboard-interactive).

$ ssh -v localhost
OpenSSH_3.9 NetBSD_Secure_Shell-20050213, OpenSSL 0.9.7d 17 Mar 2004
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: Connecting to localhost [::1] port 22.
socket: Protocol not supported
debug1: Connecting to localhost [127.0.0.1] port 22.
debug1: Connection established.
debug1: identity file /home/waaagh/.ssh/identity type -1
debug1: identity file /home/waaagh/.ssh/id_rsa type -1
debug1: identity file /home/waaagh/.ssh/id_dsa type -1
debug1: Remote protocol version 2.0, remote software version
OpenSSH_3.9 NetBSD_Secure_Shell-20050213
debug1: match: OpenSSH_3.9 NetBSD_Secure_Shell-20050213 pat OpenSSH*
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_3.9 NetBSD_Secure_Shell-200502=
13
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug1: kex: server->client aes128-cbc hmac-md5 none
debug1: kex: client->server aes128-cbc hmac-md5 none
debug1: SSH2_MSG_KEX_DH_GEX_REQUEST(1024<1024<8192) sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_GROUP
debug1: SSH2_MSG_KEX_DH_GEX_INIT sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_REPLY
debug1: Host 'localhost' is known and matches the RSA host key.
debug1: Found key in /home/waaagh/.ssh/known_hosts:1
debug1: ssh_rsa_verify: signature correct
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug1: SSH2_MSG_NEWKEYS received
debug1: SSH2_MSG_SERVICE_REQUEST sent
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug1: Authentications that can continue: publickey,keyboard-interactive
debug1: Next authentication method: publickey
debug1: Trying private key: /home/waaagh/.ssh/identity
debug1: Trying private key: /home/waaagh/.ssh/id_rsa
debug1: Trying private key: /home/waaagh/.ssh/id_dsa
debug1: Next authentication method: keyboard-interactive
debug1: Authentications that can continue: publickey,keyboard-interactive
debug1: No more authentication methods to try.
Permission denied (publickey,keyboard-interactive).

Have I done something wrong?