0:
1:
2:
3:
4: resolv ipv4 only (payload socket)
5:
6: resolv ipv6 only (payload socket)
7:
8:
9:

a: auth algo
b: auth tag length
c: cipher
d: device name
e: role
f: input file
g: unix group
h: print help text
i: local interface
j:
k: kd prf
l: ld_kdr
m: mux
n: ifconfig
o: remote port
p: local port
q:
r: remote host
s: sender id
t: device type
u: unix username
v: version
w: window size
x: post up script
y:
z: keyexchange socket path

A: master salt
B:
C: chroot directory
D: do not daemonize
E: passphrase
F: config file (not yet)
G:
H:
I: local sync interface
J:
K: master key
L: logging
M: remote sync hosts
N:
O:
P: write pid file
Q:
R: route
S: local sync port
T:
U: debug mode (no daemonize & log stdout:5)
V:
W:
X: control host
Y: rail mode
Z: