On Sat, Jul 26, 2003 at 02:22:05AM +0200, Clement Laforet wrote: > > for incoming traffic, you must use -redirect_address, but for outgoing > you have to set -alias_address. > If you want to use a specific public IP to map incoming AND outgoing > packets, you need to run 2 natd, using ipfw matching.
I'm afraid this is not exactly correct. IIRC when 5 years ago I was hacking natd and libalias to use them for transparent HTTP proxying, their internals looked rather clear. In a nutshell, they were as follows. There was a translation table inside libalias with 3 columns in it: the internal connection point (IP&port), alias point, and external point. When a packet was heading outside, its source IP&port were matched against the "internal" column, and its destination IP&port against the "external" column. If an entry were found, the packet's source IP&port would be replaced with the values from the "alias" column. When a packet was going in the opposite direction, inside, its source IP&port were matched against the "external" column, and its destination IP&port against the "alias" column. Then the packet's destination IP&port were replaced with the values from the "internal" column of the entry found. By specifying a redirect_address rule, just an entry was inserted to that table with a wildcard value for all the ports and for the external IP address. Upon matching, such an entry would clone into a new one containing the information specific for a particular session. Thus the solution was symmetric by design, without requiring 2 natd's or additional ipfw rules. P.S. As I can see, today's libalias still uses the same approach. -- Yar _______________________________________________ [EMAIL PROTECTED] mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-hackers To unsubscribe, send any mail to "[EMAIL PROTECTED]"