diff --git a/ipv4/defs_freebsd.go b/ipv4/defs_freebsd.go
index 357ce85..45152d4 100644
--- a/ipv4/defs_freebsd.go
+++ b/ipv4/defs_freebsd.go
@@ -17,39 +17,9 @@
 import "C"
 
 const (
-	sysIP_OPTIONS     = C.IP_OPTIONS
-	sysIP_HDRINCL     = C.IP_HDRINCL
-	sysIP_TOS         = C.IP_TOS
-	sysIP_TTL         = C.IP_TTL
-	sysIP_RECVOPTS    = C.IP_RECVOPTS
-	sysIP_RECVRETOPTS = C.IP_RECVRETOPTS
 	sysIP_RECVDSTADDR = C.IP_RECVDSTADDR
-	sysIP_SENDSRCADDR = C.IP_SENDSRCADDR
-	sysIP_RETOPTS     = C.IP_RETOPTS
 	sysIP_RECVIF      = C.IP_RECVIF
-	sysIP_ONESBCAST   = C.IP_ONESBCAST
-	sysIP_BINDANY     = C.IP_BINDANY
 	sysIP_RECVTTL     = C.IP_RECVTTL
-	sysIP_MINTTL      = C.IP_MINTTL
-	sysIP_DONTFRAG    = C.IP_DONTFRAG
-	sysIP_RECVTOS     = C.IP_RECVTOS
-
-	sysIP_MULTICAST_IF           = C.IP_MULTICAST_IF
-	sysIP_MULTICAST_TTL          = C.IP_MULTICAST_TTL
-	sysIP_MULTICAST_LOOP         = C.IP_MULTICAST_LOOP
-	sysIP_ADD_MEMBERSHIP         = C.IP_ADD_MEMBERSHIP
-	sysIP_DROP_MEMBERSHIP        = C.IP_DROP_MEMBERSHIP
-	sysIP_MULTICAST_VIF          = C.IP_MULTICAST_VIF
-	sysIP_ADD_SOURCE_MEMBERSHIP  = C.IP_ADD_SOURCE_MEMBERSHIP
-	sysIP_DROP_SOURCE_MEMBERSHIP = C.IP_DROP_SOURCE_MEMBERSHIP
-	sysIP_BLOCK_SOURCE           = C.IP_BLOCK_SOURCE
-	sysIP_UNBLOCK_SOURCE         = C.IP_UNBLOCK_SOURCE
-	sysMCAST_JOIN_GROUP          = C.MCAST_JOIN_GROUP
-	sysMCAST_LEAVE_GROUP         = C.MCAST_LEAVE_GROUP
-	sysMCAST_JOIN_SOURCE_GROUP   = C.MCAST_JOIN_SOURCE_GROUP
-	sysMCAST_LEAVE_SOURCE_GROUP  = C.MCAST_LEAVE_SOURCE_GROUP
-	sysMCAST_BLOCK_SOURCE        = C.MCAST_BLOCK_SOURCE
-	sysMCAST_UNBLOCK_SOURCE      = C.MCAST_UNBLOCK_SOURCE
 
 	sizeofSockaddrStorage = C.sizeof_struct_sockaddr_storage
 	sizeofSockaddrInet    = C.sizeof_struct_sockaddr_in
diff --git a/ipv4/sys_freebsd.go b/ipv4/sys_freebsd.go
index 482873d..cba9063 100644
--- a/ipv4/sys_freebsd.go
+++ b/ipv4/sys_freebsd.go
@@ -13,38 +13,40 @@
 
 	"golang.org/x/net/internal/iana"
 	"golang.org/x/net/internal/socket"
+
+	"golang.org/x/sys/unix"
 )
 
 var (
 	ctlOpts = [ctlMax]ctlOpt{
-		ctlTTL:       {sysIP_RECVTTL, 1, marshalTTL, parseTTL},
-		ctlDst:       {sysIP_RECVDSTADDR, net.IPv4len, marshalDst, parseDst},
-		ctlInterface: {sysIP_RECVIF, syscall.SizeofSockaddrDatalink, marshalInterface, parseInterface},
+		ctlTTL:       {unix.IP_RECVTTL, 1, marshalTTL, parseTTL},
+		ctlDst:       {unix.IP_RECVDSTADDR, net.IPv4len, marshalDst, parseDst},
+		ctlInterface: {unix.IP_RECVIF, syscall.SizeofSockaddrDatalink, marshalInterface, parseInterface},
 	}
 
 	sockOpts = map[int]*sockOpt{
-		ssoTOS:                {Option: socket.Option{Level: iana.ProtocolIP, Name: sysIP_TOS, Len: 4}},
-		ssoTTL:                {Option: socket.Option{Level: iana.ProtocolIP, Name: sysIP_TTL, Len: 4}},
-		ssoMulticastTTL:       {Option: socket.Option{Level: iana.ProtocolIP, Name: sysIP_MULTICAST_TTL, Len: 1}},
-		ssoMulticastInterface: {Option: socket.Option{Level: iana.ProtocolIP, Name: sysIP_MULTICAST_IF, Len: 4}},
-		ssoMulticastLoopback:  {Option: socket.Option{Level: iana.ProtocolIP, Name: sysIP_MULTICAST_LOOP, Len: 4}},
-		ssoReceiveTTL:         {Option: socket.Option{Level: iana.ProtocolIP, Name: sysIP_RECVTTL, Len: 4}},
-		ssoReceiveDst:         {Option: socket.Option{Level: iana.ProtocolIP, Name: sysIP_RECVDSTADDR, Len: 4}},
-		ssoReceiveInterface:   {Option: socket.Option{Level: iana.ProtocolIP, Name: sysIP_RECVIF, Len: 4}},
-		ssoHeaderPrepend:      {Option: socket.Option{Level: iana.ProtocolIP, Name: sysIP_HDRINCL, Len: 4}},
-		ssoJoinGroup:          {Option: socket.Option{Level: iana.ProtocolIP, Name: sysMCAST_JOIN_GROUP, Len: sizeofGroupReq}, typ: ssoTypeGroupReq},
-		ssoLeaveGroup:         {Option: socket.Option{Level: iana.ProtocolIP, Name: sysMCAST_LEAVE_GROUP, Len: sizeofGroupReq}, typ: ssoTypeGroupReq},
-		ssoJoinSourceGroup:    {Option: socket.Option{Level: iana.ProtocolIP, Name: sysMCAST_JOIN_SOURCE_GROUP, Len: sizeofGroupSourceReq}, typ: ssoTypeGroupSourceReq},
-		ssoLeaveSourceGroup:   {Option: socket.Option{Level: iana.ProtocolIP, Name: sysMCAST_LEAVE_SOURCE_GROUP, Len: sizeofGroupSourceReq}, typ: ssoTypeGroupSourceReq},
-		ssoBlockSourceGroup:   {Option: socket.Option{Level: iana.ProtocolIP, Name: sysMCAST_BLOCK_SOURCE, Len: sizeofGroupSourceReq}, typ: ssoTypeGroupSourceReq},
-		ssoUnblockSourceGroup: {Option: socket.Option{Level: iana.ProtocolIP, Name: sysMCAST_UNBLOCK_SOURCE, Len: sizeofGroupSourceReq}, typ: ssoTypeGroupSourceReq},
+		ssoTOS:                {Option: socket.Option{Level: iana.ProtocolIP, Name: unix.IP_TOS, Len: 4}},
+		ssoTTL:                {Option: socket.Option{Level: iana.ProtocolIP, Name: unix.IP_TTL, Len: 4}},
+		ssoMulticastTTL:       {Option: socket.Option{Level: iana.ProtocolIP, Name: unix.IP_MULTICAST_TTL, Len: 1}},
+		ssoMulticastInterface: {Option: socket.Option{Level: iana.ProtocolIP, Name: unix.IP_MULTICAST_IF, Len: 4}},
+		ssoMulticastLoopback:  {Option: socket.Option{Level: iana.ProtocolIP, Name: unix.IP_MULTICAST_LOOP, Len: 4}},
+		ssoReceiveTTL:         {Option: socket.Option{Level: iana.ProtocolIP, Name: unix.IP_RECVTTL, Len: 4}},
+		ssoReceiveDst:         {Option: socket.Option{Level: iana.ProtocolIP, Name: unix.IP_RECVDSTADDR, Len: 4}},
+		ssoReceiveInterface:   {Option: socket.Option{Level: iana.ProtocolIP, Name: unix.IP_RECVIF, Len: 4}},
+		ssoHeaderPrepend:      {Option: socket.Option{Level: iana.ProtocolIP, Name: unix.IP_HDRINCL, Len: 4}},
+		ssoJoinGroup:          {Option: socket.Option{Level: iana.ProtocolIP, Name: unix.MCAST_JOIN_GROUP, Len: sizeofGroupReq}, typ: ssoTypeGroupReq},
+		ssoLeaveGroup:         {Option: socket.Option{Level: iana.ProtocolIP, Name: unix.MCAST_LEAVE_GROUP, Len: sizeofGroupReq}, typ: ssoTypeGroupReq},
+		ssoJoinSourceGroup:    {Option: socket.Option{Level: iana.ProtocolIP, Name: unix.MCAST_JOIN_SOURCE_GROUP, Len: sizeofGroupSourceReq}, typ: ssoTypeGroupSourceReq},
+		ssoLeaveSourceGroup:   {Option: socket.Option{Level: iana.ProtocolIP, Name: unix.MCAST_LEAVE_SOURCE_GROUP, Len: sizeofGroupSourceReq}, typ: ssoTypeGroupSourceReq},
+		ssoBlockSourceGroup:   {Option: socket.Option{Level: iana.ProtocolIP, Name: unix.MCAST_BLOCK_SOURCE, Len: sizeofGroupSourceReq}, typ: ssoTypeGroupSourceReq},
+		ssoUnblockSourceGroup: {Option: socket.Option{Level: iana.ProtocolIP, Name: unix.MCAST_UNBLOCK_SOURCE, Len: sizeofGroupSourceReq}, typ: ssoTypeGroupSourceReq},
 	}
 )
 
 func init() {
 	freebsdVersion, _ = syscall.SysctlUint32("kern.osreldate")
 	if freebsdVersion >= 1000000 {
-		sockOpts[ssoMulticastInterface] = &sockOpt{Option: socket.Option{Level: iana.ProtocolIP, Name: sysIP_MULTICAST_IF, Len: sizeofIPMreqn}, typ: ssoTypeIPMreqn}
+		sockOpts[ssoMulticastInterface] = &sockOpt{Option: socket.Option{Level: iana.ProtocolIP, Name: unix.IP_MULTICAST_IF, Len: sizeofIPMreqn}, typ: ssoTypeIPMreqn}
 	}
 	if runtime.GOOS == "freebsd" && runtime.GOARCH == "386" {
 		archs, _ := syscall.Sysctl("kern.supported_archs")
diff --git a/ipv4/zsys_freebsd_386.go b/ipv4/zsys_freebsd_386.go
index 136e2b8..9a0e328 100644
--- a/ipv4/zsys_freebsd_386.go
+++ b/ipv4/zsys_freebsd_386.go
@@ -4,39 +4,9 @@
 package ipv4
 
 const (
-	sysIP_OPTIONS     = 0x1
-	sysIP_HDRINCL     = 0x2
-	sysIP_TOS         = 0x3
-	sysIP_TTL         = 0x4
-	sysIP_RECVOPTS    = 0x5
-	sysIP_RECVRETOPTS = 0x6
 	sysIP_RECVDSTADDR = 0x7
-	sysIP_SENDSRCADDR = 0x7
-	sysIP_RETOPTS     = 0x8
 	sysIP_RECVIF      = 0x14
-	sysIP_ONESBCAST   = 0x17
-	sysIP_BINDANY     = 0x18
 	sysIP_RECVTTL     = 0x41
-	sysIP_MINTTL      = 0x42
-	sysIP_DONTFRAG    = 0x43
-	sysIP_RECVTOS     = 0x44
-
-	sysIP_MULTICAST_IF           = 0x9
-	sysIP_MULTICAST_TTL          = 0xa
-	sysIP_MULTICAST_LOOP         = 0xb
-	sysIP_ADD_MEMBERSHIP         = 0xc
-	sysIP_DROP_MEMBERSHIP        = 0xd
-	sysIP_MULTICAST_VIF          = 0xe
-	sysIP_ADD_SOURCE_MEMBERSHIP  = 0x46
-	sysIP_DROP_SOURCE_MEMBERSHIP = 0x47
-	sysIP_BLOCK_SOURCE           = 0x48
-	sysIP_UNBLOCK_SOURCE         = 0x49
-	sysMCAST_JOIN_GROUP          = 0x50
-	sysMCAST_LEAVE_GROUP         = 0x51
-	sysMCAST_JOIN_SOURCE_GROUP   = 0x52
-	sysMCAST_LEAVE_SOURCE_GROUP  = 0x53
-	sysMCAST_BLOCK_SOURCE        = 0x54
-	sysMCAST_UNBLOCK_SOURCE      = 0x55
 
 	sizeofSockaddrStorage = 0x80
 	sizeofSockaddrInet    = 0x10
diff --git a/ipv4/zsys_freebsd_amd64.go b/ipv4/zsys_freebsd_amd64.go
index 4f730f1..143623b 100644
--- a/ipv4/zsys_freebsd_amd64.go
+++ b/ipv4/zsys_freebsd_amd64.go
@@ -4,39 +4,9 @@
 package ipv4
 
 const (
-	sysIP_OPTIONS     = 0x1
-	sysIP_HDRINCL     = 0x2
-	sysIP_TOS         = 0x3
-	sysIP_TTL         = 0x4
-	sysIP_RECVOPTS    = 0x5
-	sysIP_RECVRETOPTS = 0x6
 	sysIP_RECVDSTADDR = 0x7
-	sysIP_SENDSRCADDR = 0x7
-	sysIP_RETOPTS     = 0x8
 	sysIP_RECVIF      = 0x14
-	sysIP_ONESBCAST   = 0x17
-	sysIP_BINDANY     = 0x18
 	sysIP_RECVTTL     = 0x41
-	sysIP_MINTTL      = 0x42
-	sysIP_DONTFRAG    = 0x43
-	sysIP_RECVTOS     = 0x44
-
-	sysIP_MULTICAST_IF           = 0x9
-	sysIP_MULTICAST_TTL          = 0xa
-	sysIP_MULTICAST_LOOP         = 0xb
-	sysIP_ADD_MEMBERSHIP         = 0xc
-	sysIP_DROP_MEMBERSHIP        = 0xd
-	sysIP_MULTICAST_VIF          = 0xe
-	sysIP_ADD_SOURCE_MEMBERSHIP  = 0x46
-	sysIP_DROP_SOURCE_MEMBERSHIP = 0x47
-	sysIP_BLOCK_SOURCE           = 0x48
-	sysIP_UNBLOCK_SOURCE         = 0x49
-	sysMCAST_JOIN_GROUP          = 0x50
-	sysMCAST_LEAVE_GROUP         = 0x51
-	sysMCAST_JOIN_SOURCE_GROUP   = 0x52
-	sysMCAST_LEAVE_SOURCE_GROUP  = 0x53
-	sysMCAST_BLOCK_SOURCE        = 0x54
-	sysMCAST_UNBLOCK_SOURCE      = 0x55
 
 	sizeofSockaddrStorage = 0x80
 	sizeofSockaddrInet    = 0x10
diff --git a/ipv4/zsys_freebsd_arm.go b/ipv4/zsys_freebsd_arm.go
index 4f730f1..143623b 100644
--- a/ipv4/zsys_freebsd_arm.go
+++ b/ipv4/zsys_freebsd_arm.go
@@ -4,39 +4,9 @@
 package ipv4
 
 const (
-	sysIP_OPTIONS     = 0x1
-	sysIP_HDRINCL     = 0x2
-	sysIP_TOS         = 0x3
-	sysIP_TTL         = 0x4
-	sysIP_RECVOPTS    = 0x5
-	sysIP_RECVRETOPTS = 0x6
 	sysIP_RECVDSTADDR = 0x7
-	sysIP_SENDSRCADDR = 0x7
-	sysIP_RETOPTS     = 0x8
 	sysIP_RECVIF      = 0x14
-	sysIP_ONESBCAST   = 0x17
-	sysIP_BINDANY     = 0x18
 	sysIP_RECVTTL     = 0x41
-	sysIP_MINTTL      = 0x42
-	sysIP_DONTFRAG    = 0x43
-	sysIP_RECVTOS     = 0x44
-
-	sysIP_MULTICAST_IF           = 0x9
-	sysIP_MULTICAST_TTL          = 0xa
-	sysIP_MULTICAST_LOOP         = 0xb
-	sysIP_ADD_MEMBERSHIP         = 0xc
-	sysIP_DROP_MEMBERSHIP        = 0xd
-	sysIP_MULTICAST_VIF          = 0xe
-	sysIP_ADD_SOURCE_MEMBERSHIP  = 0x46
-	sysIP_DROP_SOURCE_MEMBERSHIP = 0x47
-	sysIP_BLOCK_SOURCE           = 0x48
-	sysIP_UNBLOCK_SOURCE         = 0x49
-	sysMCAST_JOIN_GROUP          = 0x50
-	sysMCAST_LEAVE_GROUP         = 0x51
-	sysMCAST_JOIN_SOURCE_GROUP   = 0x52
-	sysMCAST_LEAVE_SOURCE_GROUP  = 0x53
-	sysMCAST_BLOCK_SOURCE        = 0x54
-	sysMCAST_UNBLOCK_SOURCE      = 0x55
 
 	sizeofSockaddrStorage = 0x80
 	sizeofSockaddrInet    = 0x10
diff --git a/ipv4/zsys_freebsd_arm64.go b/ipv4/zsys_freebsd_arm64.go
index ecebf32..1be7023 100644
--- a/ipv4/zsys_freebsd_arm64.go
+++ b/ipv4/zsys_freebsd_arm64.go
@@ -4,39 +4,9 @@
 package ipv4
 
 const (
-	sysIP_OPTIONS     = 0x1
-	sysIP_HDRINCL     = 0x2
-	sysIP_TOS         = 0x3
-	sysIP_TTL         = 0x4
-	sysIP_RECVOPTS    = 0x5
-	sysIP_RECVRETOPTS = 0x6
 	sysIP_RECVDSTADDR = 0x7
-	sysIP_SENDSRCADDR = 0x7
-	sysIP_RETOPTS     = 0x8
 	sysIP_RECVIF      = 0x14
-	sysIP_ONESBCAST   = 0x17
-	sysIP_BINDANY     = 0x18
 	sysIP_RECVTTL     = 0x41
-	sysIP_MINTTL      = 0x42
-	sysIP_DONTFRAG    = 0x43
-	sysIP_RECVTOS     = 0x44
-
-	sysIP_MULTICAST_IF           = 0x9
-	sysIP_MULTICAST_TTL          = 0xa
-	sysIP_MULTICAST_LOOP         = 0xb
-	sysIP_ADD_MEMBERSHIP         = 0xc
-	sysIP_DROP_MEMBERSHIP        = 0xd
-	sysIP_MULTICAST_VIF          = 0xe
-	sysIP_ADD_SOURCE_MEMBERSHIP  = 0x46
-	sysIP_DROP_SOURCE_MEMBERSHIP = 0x47
-	sysIP_BLOCK_SOURCE           = 0x48
-	sysIP_UNBLOCK_SOURCE         = 0x49
-	sysMCAST_JOIN_GROUP          = 0x50
-	sysMCAST_LEAVE_GROUP         = 0x51
-	sysMCAST_JOIN_SOURCE_GROUP   = 0x52
-	sysMCAST_LEAVE_SOURCE_GROUP  = 0x53
-	sysMCAST_BLOCK_SOURCE        = 0x54
-	sysMCAST_UNBLOCK_SOURCE      = 0x55
 
 	sizeofSockaddrStorage = 0x80
 	sizeofSockaddrInet    = 0x10