Unconditionally enable support for O_IPSEC opcode. IPsec support can be loaded as kernel module, thus do not depend from kernel option IPSEC and always build O_IPSEC opcode implementation as enabled.
Do not invoke IPv4 NAT handler for non IPv4 packets. Libalias expects a packet is IPv4. And in case when it is IPv6, it just translates them as IPv4. This leads to corruption and in some cases to panics. In particular a panic can happen when value of ip6_plen modified to something that leads to IP fragmentation, but actual packet length does not match the IP length. Packets that are not IPv4 will be dropped by NAT rule.