+ dhcpv6 server; rewrite dhcpv4 server; changed API

go.mod

@@ -9,13 +9,17 @@ require (
 	github.com/NYTimes/gziphandler v1.1.1
 	github.com/fsnotify/fsnotify v1.4.7
 	github.com/gobuffalo/packr v1.30.1
+	github.com/hugelgupf/socketpair v0.0.0-20190730060125-05d35a94e714 // indirect
+	github.com/insomniacslk/dhcp v0.0.0-20200420235442-ed3125c2efe7
 	github.com/joomcode/errorx v1.0.1
 	github.com/kardianos/service v1.1.0
-	github.com/krolaw/dhcp4 v0.0.0-20180925202202-7cead472c414
+	github.com/mdlayher/ethernet v0.0.0-20190606142754-0394541c37b7 // indirect
+	github.com/mdlayher/raw v0.0.0-20191009151244-50f2db8cc065 // indirect
 	github.com/miekg/dns v1.1.29
 	github.com/pkg/errors v0.9.1
 	github.com/sparrc/go-ping v0.0.0-20190613174326-4e5b6552494c
 	github.com/stretchr/testify v1.5.1
+	github.com/u-root/u-root v6.0.0+incompatible // indirect
 	go.etcd.io/bbolt v1.3.4
 	golang.org/x/crypto v0.0.0-20200403201458-baeed622b8d8
 	golang.org/x/net v0.0.0-20200324143707-d3edc9973b7e