This method sends Fake Packet with the TCP SEQ/ACK numbers "in the past":
-66000 is used for ACK (right out of the ACK permissive window in Linux stack),
-10000 is used for SEQ (without any reasoning).
This method is pretty effective in Russia.
It also could be handy in a networks which prohibit changing TTL values
(mobile networks with tethering block/premium feature).
Before: --set-ttl and --wrong-chksum generated single Fake Packet with both low TTL and incorrect checksum.
Now: --set-ttl and --wrong-chksum generate two packets: one with low TTL, another with incorrect checksum.
ValdikSS