IP dynamic address hack-port v0.03¶
This stuff allows diald ONESHOT connections to get established by dynamically changing packet source address (and socket’s if local procs). It is implemented for TCP diald-box connections(1) and IP_MASQuerading(2).
If enabled1 and forwarding interface has changed:
Socket (and packet) source address is rewritten ON RETRANSMISSIONS while in SYN_SENT state (diald-box processes).
Out-bounded MASQueraded source address changes ON OUTPUT (when internal host does retransmission) until a packet from outside is received by the tunnel.
This is specially helpful for auto dialup links (diald), where the
actual outgoing address is unknown at the moment the link is
going up. So, the same (local AND masqueraded) connections requests that
bring the link up will be able to get established.
At boot, by default no address rewriting is attempted.
# echo 1 > /proc/sys/net/ipv4/ip_dynaddr
To enable verbose mode:
# echo 2 > /proc/sys/net/ipv4/ip_dynaddr
To disable (default):
# echo 0 > /proc/sys/net/ipv4/ip_dynaddr