diff --git a/net/cidr/range-v4.go b/net/cidr/range-v4.go
new file mode 100644
index 0000000..6bbf41c
--- /dev/null
+++ b/net/cidr/range-v4.go
@@ -0,0 +1,128 @@
+package cidr
+
+import (
+	"fmt"
+	"net"
+
+	"git.loafle.net/overflow/util-go/net/converter"
+)
+
+type cidrRangeIPv4 struct {
+	cidrNet *net.IPNet
+}
+
+func (cr *cidrRangeIPv4) Contains(ip net.IP) bool {
+	return cr.cidrNet.Contains(ip)
+}
+
+func (cr *cidrRangeIPv4) First() net.IP {
+	nIP := cr.Network()
+	return cr.Next(nIP)
+}
+
+func (cr *cidrRangeIPv4) Last() net.IP {
+	bIP := cr.Broadcast()
+	return cr.Previous(bIP)
+}
+
+func (cr *cidrRangeIPv4) Range() []net.IP {
+	fIP := cr.First()
+	if nil == fIP {
+		return nil
+	}
+	lIP := cr.Last()
+	if nil == lIP {
+		return nil
+	}
+	fNum := converter.IPv4ToInt(fIP.To4())
+	lNum := converter.IPv4ToInt(lIP.To4())
+
+	r := make([]net.IP, 0)
+	for i := fNum; i <= lNum; i++ {
+		r = append(r, converter.IntToIPv4(i))
+	}
+	return r
+}
+
+// (!Contains(startIP) || !Contains(endIP)) return nil
+// (startIP > endIP) return nil
+// (nil != startIP && nil != endIP) return (startIP ~ endIP) + include - exclude
+// (nil == startIP || nil == endIP) return include - exclude
+func (cr *cidrRangeIPv4) Ranges(startIP net.IP, endIP net.IP, include []net.IP, exclude []net.IP) ([]net.IP, error) {
+
+	res := make(map[int32]bool)
+
+	if nil != startIP && nil != endIP {
+		if !cr.Contains(startIP) {
+			return nil, fmt.Errorf("CIDR Range: CIDR not contains start ip[%v]", startIP)
+		}
+		if !cr.Contains(endIP) {
+			return nil, fmt.Errorf("CIDR Range: CIDR not contains end ip[%v]", endIP)
+		}
+		sNum := converter.IPv4ToInt(startIP.To4())
+		eNum := converter.IPv4ToInt(endIP.To4())
+		if sNum > eNum {
+			return nil, fmt.Errorf("CIDR Range: Start IP[%v] must smaller then End IP[%v]", startIP, endIP)
+		}
+		for i := sNum; i <= eNum; i++ {
+			res[i] = true
+		}
+	}
+
+	if nil != include {
+		for _, in := range include {
+			iNum := converter.IPv4ToInt(in.To4())
+			if _, ok := res[iNum]; !ok {
+				res[iNum] = true
+			}
+		}
+	}
+
+	if nil != exclude {
+		for _, ex := range exclude {
+			iNum := converter.IPv4ToInt(ex.To4())
+			if _, ok := res[iNum]; ok {
+				delete(res, iNum)
+			}
+		}
+	}
+
+	r := make([]net.IP, 0)
+	for k, _ := range res {
+		r = append(r, converter.IntToIPv4(k))
+	}
+
+	return r, nil
+}
+
+func (cr *cidrRangeIPv4) Broadcast() net.IP {
+	ip := cr.cidrNet.IP.To4()
+	bIP := net.IPv4(0, 0, 0, 0).To4()
+	for i := 0; i < len(bIP); i++ {
+		bIP[i] = ip[i] | ^cr.cidrNet.Mask[i]
+	}
+	return bIP
+}
+
+func (cr *cidrRangeIPv4) Network() net.IP {
+	ip := cr.cidrNet.IP.To4()
+	return ip.Mask(cr.cidrNet.Mask)
+}
+
+func (cr *cidrRangeIPv4) Next(ip net.IP) net.IP {
+	nNum := converter.IPv4ToInt(ip.To4()) + 1
+	nIP := converter.IntToIPv4(nNum)
+	if cr.Contains(nIP) {
+		return nIP
+	}
+	return nil
+}
+
+func (cr *cidrRangeIPv4) Previous(ip net.IP) net.IP {
+	nNum := converter.IPv4ToInt(ip.To4()) - 1
+	nIP := converter.IntToIPv4(nNum)
+	if cr.Contains(nIP) {
+		return nIP
+	}
+	return nil
+}
diff --git a/net/cidr/range-v6.go b/net/cidr/range-v6.go
new file mode 100644
index 0000000..440ad0b
--- /dev/null
+++ b/net/cidr/range-v6.go
@@ -0,0 +1,43 @@
+package cidr
+
+import "net"
+
+type cidrRangeIPv6 struct {
+	cidrNet *net.IPNet
+}
+
+func (cr *cidrRangeIPv6) Contains(ip net.IP) bool {
+	return cr.cidrNet.Contains(ip)
+}
+
+func (cr *cidrRangeIPv6) First() net.IP {
+	return nil
+}
+
+func (cr *cidrRangeIPv6) Last() net.IP {
+	return nil
+}
+
+func (cr *cidrRangeIPv6) Range() []net.IP {
+	return nil
+}
+
+func (cr *cidrRangeIPv6) Ranges(startIP net.IP, endIP net.IP, include []net.IP, exclude []net.IP) ([]net.IP, error) {
+	return nil, nil
+}
+
+func (cr *cidrRangeIPv6) Broadcast() net.IP {
+	return nil
+}
+
+func (cr *cidrRangeIPv6) Network() net.IP {
+	return nil
+}
+
+func (cr *cidrRangeIPv6) Next(ip net.IP) net.IP {
+	return nil
+}
+
+func (cr *cidrRangeIPv6) Previous(ip net.IP) net.IP {
+	return nil
+}
diff --git a/net/cidr/range.go b/net/cidr/range.go
new file mode 100644
index 0000000..9d908ee
--- /dev/null
+++ b/net/cidr/range.go
@@ -0,0 +1,44 @@
+package cidr
+
+import (
+	"fmt"
+	"net"
+)
+
+func NewCIDRRanger(cidr string) (CIDRRanger, error) {
+	_, nIPNet, err := net.ParseCIDR(cidr)
+	if nil != err {
+		return nil, err
+	}
+
+	switch len(nIPNet.IP) {
+	case net.IPv4len:
+		cr := &cidrRangeIPv4{
+			cidrNet: nIPNet,
+		}
+		return cr, nil
+	case net.IPv6len:
+		cr := &cidrRangeIPv6{
+			cidrNet: nIPNet,
+		}
+		return cr, nil
+	default:
+		return nil, fmt.Errorf("Net: not supported IP length")
+	}
+}
+
+type CIDRRanger interface {
+	Contains(ip net.IP) bool
+	First() net.IP
+	Last() net.IP
+	Range() []net.IP
+	// (!Contains(startIP) || !Contains(endIP)) return error
+	// (startIP > endIP) return error
+	// (nil != startIP && nil != endIP) return (startIP ~ endIP) + include - exclude
+	// (nil == startIP || nil == endIP) return include - exclude
+	Ranges(startIP net.IP, endIP net.IP, include []net.IP, exclude []net.IP) ([]net.IP, error)
+	Broadcast() net.IP
+	Network() net.IP
+	Next(ip net.IP) net.IP
+	Previous(ip net.IP) net.IP
+}
diff --git a/net/converter/ip-v4.go b/net/converter/ip-v4.go
new file mode 100644
index 0000000..694e778
--- /dev/null
+++ b/net/converter/ip-v4.go
@@ -0,0 +1,16 @@
+package converter
+
+import (
+	"encoding/binary"
+	"net"
+)
+
+func IPv4ToInt(ip net.IP) int32 {
+	return int32(binary.BigEndian.Uint32(ip.To4()))
+}
+
+func IntToIPv4(n int32) net.IP {
+	b := make([]byte, 4)
+	binary.BigEndian.PutUint32(b, uint32(n))
+	return net.IP(b)
+}
diff --git a/net/converter/ip-v6.go b/net/converter/ip-v6.go
new file mode 100644
index 0000000..676ad64
--- /dev/null
+++ b/net/converter/ip-v6.go
@@ -0,0 +1,15 @@
+package converter
+
+import (
+	"net"
+)
+
+// Not implemented
+func IPv6ToInt(ip net.IP) int32 {
+	return 0
+}
+
+// Not implemented
+func IntToIPv6(n int32) net.IP {
+	return nil
+}
diff --git a/net/converter/ip.go b/net/converter/ip.go
new file mode 100644
index 0000000..5768225
--- /dev/null
+++ b/net/converter/ip.go
@@ -0,0 +1,17 @@
+package converter
+
+import (
+	"fmt"
+	"net"
+)
+
+func IPToInt(ip net.IP) (int32, error) {
+	switch len(ip) {
+	case net.IPv4len:
+		return IPv4ToInt(ip), nil
+	case net.IPv6len:
+		return IPv6ToInt(ip), nil
+	default:
+		return 0, fmt.Errorf("Net: not supported IP length")
+	}
+}
diff --git a/net/converter/mac.go b/net/converter/mac.go
new file mode 100644
index 0000000..45777b5
--- /dev/null
+++ b/net/converter/mac.go
@@ -0,0 +1,18 @@
+package converter
+
+import (
+	"net"
+	"regexp"
+	"strconv"
+)
+
+var (
+	macStripRegexp = regexp.MustCompile(`[^a-fA-F0-9]`)
+)
+
+func MacToUint64(hwAddr net.HardwareAddr) (uint64, error) {
+	mac := hwAddr.String()
+	hex := macStripRegexp.ReplaceAllLiteralString(mac, "")
+
+	return strconv.ParseUint(hex, 16, 64)
+}