This article is from the netrek FAQ, by Tom Holub doosh@best.com with numerous contributions by others.
It's possible to modify the client source to do lots of tedious tasks
(like aiming, dodging, that sort of thing) for you. Since this gives
you a big advantage over a mere human, netrek has a way of knowing
whether you have a client that was compiled by the netrek Gods or by
you. If you compiled it, netrek will assume it's a cyborg, and will
kick you out if it's not cyborg hours.
You might also run into this problem if you are playing behind a NAT
gateway or firewall. The netrek server initiates a "call-back" on a
random port, which fails in most such configurations. To get around
this, you can turn on a feature called UDP_PORTSWAP in your
client. Put the following in your .netrekrc file (or netrekrc on
Windows):
tryShort: on tryUDP: on udpTryPortswap: on udpDebug: off
udpClientSend: 2 udpClientRecv: 3 udpSequenceChk: on
There are several different messages you can get when your binary
isn't what the server is expecting:
1. "User binary failed to verify."
The server is expecting a standard blessed client; read the
Netrek FTP List to find out where you can get one.
2. "No customized binaries. Please use a blessed one."
You have an RSA client, but the key for your client isn't on the
list. Mail the server god if you think your key should be
included.
3. "You need a spiffy new RSA client for this server!"
You have a standard blessed client (or an unblessed client) but
the server accepts only RSA clients; read the Netrek FTP List to
find out where you can get one.
If you are interested in playing a cyborg, get the source from one of
the FTP sites and start hacking. It's probably not a good idea for new
players to use cyborgs; cyborg players get called lots of nasty names,
and they tend not to learn how to play the game (since their client is
doing most of the work).
 
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