TODO: bridge mode, finally? TODO: gcm mode? TODO: replace transport bits by transport endpoint structs? TODO: http://incog-izick.blogspot.de/2011/08/using-openssl-aes-gcm.html TODO: http://stackoverflow.com/questions/12153009/openssl-c-example-of-aes-gcm-using-evp-interfaces TODO: verify TODO: make sense of overhead calculation TODO: if-up &c should not be scripts? TODO: ipv6 TODO: gvpectrl should not use default privatekey,. or maybe document it better TODO: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=828336