* udptunnel-reconf inittab entries default to having </dev/null.
* udptunnel-reconf understands forbid_remote set to `-'.
* forbid_remote is a per-tunnel option.
+ * udptunnel-vpn-config.m4 allows global file to override as intended.
* www-cgi passes HTTP_COOKIE header.
+ * indirect ssh via V_sshinvoke.
--