[NETFILTER]: sip conntrack: better NAT handling
The NAT handling of the SIP helper has a few problems:
- Request headers are only mangled in the reply direction, From/To headers
not at all, which can lead to authentication failures with DNAT in case
the authentication domain is the IP address
- Contact headers in responses are only mangled for REGISTER responses
- Headers may be mangled even though they contain addresses not
participating in the connection, like alternative addresses
- Packets are droppen when domain names are used where the helper expects
IP addresses
This patch takes a different approach, instead of fixed rules what field
to mangle to what content, it adds symetric mapping of From/To/Via/Contact
headers, which allows to deal properly with echoed addresses in responses
and foreign addresses not belonging to the connection.
Signed-off-by: Patrick McHardy <kaber@trash.net>
3 files changed