Remove support for S/Key
Most people will 1) be using modern multi-factor authentication methods
like TOTP/OATH etc and 2) be getting support for multi-factor
authentication via PAM or BSD Auth.
diff --git a/readconf.c b/readconf.c
index 4ab312f..4b11bab 100644
--- a/readconf.c
+++ b/readconf.c
@@ -230,7 +230,7 @@
{ "dsaauthentication", oPubkeyAuthentication }, /* alias */
{ "hostbasedauthentication", oHostbasedAuthentication },
{ "challengeresponseauthentication", oChallengeResponseAuthentication },
- { "skeyauthentication", oChallengeResponseAuthentication }, /* alias */
+ { "skeyauthentication", oUnsupported },
{ "tisauthentication", oChallengeResponseAuthentication }, /* alias */
{ "identityfile", oIdentityFile },
{ "identityfile2", oIdentityFile }, /* obsolete */