Technical issues

Issues in NAT/firewall-related tools, and more

Incompatible with some protocols, like ftp
Need special support
Inbound accesses are almost impossible
IPv4->IPv6
Address pool
Need some reserved IPv4/v6 address space
State management for translating box
Security
How to authenticate valid user/host for the translator?
IPsec is unusable over translators
IPv4-to-v6 address mapping (DNS issue)