diff --git a/ipconfig.go b/ipconfig.go
index da6a2a8..6459faf 100644
--- a/ipconfig.go
+++ b/ipconfig.go
@@ -8,6 +8,22 @@ import (
 
 type IPConfigs []*IPConfig
 
+func (c *IPConfigs) Set(index int, ipc *IPConfig) {
+	l := len(*c)
+	if index >= l {
+		n := make(IPConfigs, index+1)
+		copy(n, *c)
+		n[index] = ipc
+		*c = n
+		return
+	}
+	if l == 0 {
+		*c = append(*c, ipc)
+		return
+	}
+	(*c)[index] = ipc
+}
+
 func (c IPConfigs) Get(index int) *IPConfig {
 	if len(c)-1 >= index {
 		return c[index]
diff --git a/network.go b/network.go
index 1e55ece..1ec084c 100644
--- a/network.go
+++ b/network.go
@@ -9,6 +9,22 @@ import (
 
 type NetworkDevices []*NetworkDevice
 
+func (c *NetworkDevices) Set(index int, d *NetworkDevice) {
+	l := len(*c)
+	if index >= l {
+		n := make(NetworkDevices, index+1)
+		copy(n, *c)
+		n[index] = d
+		*c = n
+		return
+	}
+	if l == 0 {
+		*c = append(*c, d)
+		return
+	}
+	(*c)[index] = d
+}
+
 func (c NetworkDevices) Get(index int) *NetworkDevice {
 	if len(c)-1 >= index {
 		return c[index]
diff --git a/server.go b/server.go
index c1a1590..c8423fc 100644
--- a/server.go
+++ b/server.go
@@ -34,9 +34,17 @@ func (s *Server) body() (httpbody, error) {
 	userdata, err := s.UserData.String()
 	body["ciuserdata"] = userdata
 	for i, n := range s.NetDevices {
+		if n == nil {
+			body["net"+strconv.Itoa(i)] = ""
+			continue
+		}
 		body["net"+strconv.Itoa(i)] = n.String()
 	}
 	for i, ip := range s.IPConfig {
+		if ip == nil {
+			body["ipconfig"+strconv.Itoa(i)] = ""
+			continue
+		}
 		body["ipconfig"+strconv.Itoa(i)] = ip.String()
 	}
 	return body, err