Re: tcpserver & IPv6
Erwin Hoffmann <feh <at> fehcom.de>
2012-05-22 09:24:27 GMT
Hi Florian (and all who are interested),
currently I'm working on IPv6, and particular it's integration into ucspi-ssl and qmail.
Felix already did most of the coding
Let me try to explain parts of the problem:
Your IPvX settings:
a) In your setting, you use IPv6 enabled tcpserver to catch any TCP packet for port 25.
You bind tcpserver to ANY available IP address by means of the '0'
b) tcpserver will happily accept any IPv4 AND IPv6 packet on any (at start) available IP address.
c) The IPv4 address your host has is '0.0.0.0' (unspecified), '127.0.0.1' (loopback) and the
dedicated address, lets lay 220.127.116.11.
d) IPv6 address you host has is '::' (unspecified), '::1' (loopback), the link-local LLU
address (fe80:....), and the Global IPv4 address, typically 2001:......
e) In case you have turned on IPv6 privacy extension, additional LLU AND Global addresses
will come and go. I doubt, this is going to work with tcpserver anyway.
f) Let's consider tcpserver receives an IPvX packet. It needs to look inside the cdb.
Here you may have defined some IP based rules, typically '127.0.0.1:allow'.
g) The kernel of your OS will translate any IPv4 DA in the packet to an IPv4-mapped IPv6 address.
The lookup will fail.