Setting up slip

[Nick Sayer]

I have a Sun 2/170 and have recently gotten slipware
for it. At school we have a couple sun3s and a vax on
an ethernet, and will soon be hooked up to the internet
(via a slip link from the vax, but that's not important).

The sun 2 is quack, and the sun 3 I have been trying to
connect to is uop. quack is 138.9.100.1, and uop is
138.9.200.1 (quack's address is arbitrary - in future
it may need to be changed to something totally different
for various reasons). Using a 2-3/3-2 cable and two serial
ports on quack, I have gotten telnet to talk to itself
using the instructions in the slip 4.0 README, thus:

quack% sliplogin 138.9.100.10 138.9.100.11 > /dev/tty03 < /dev/tty03 &
quack% sliplogin 138.9.100.11 138.9.100.10 > /dev/tty04 < /dev/tty04 &
quack% ping 138.9.100.10
138.9.100.10 is alive
... etc

slip has been used in the past at uop, so I did not perform a loopback
test there.

I am trying to hook the two machines up via slip on a non-permanent
basis. I.e. If I want to do some ftping from the internet (when
they get it up), it's seemingly more convenient to "slip"
into uop, then ftp directly into quack (over the phone) than
to ftp to uop, then kermit to quack, or some such nonesense.
I am familiar with unix, but just starting TCP/IP. I plan to hook quack
up to Amateur Packet Radio TCP/IP, but that's going more slowly.

I have tried this:

uop% sliplogin 138.9.100.4 138.9.200.4 255.255.255.0
~Clocal command: sliplogin 138.9.200.4 138.9.100.4 255.255.255.0

If I try to ping ..200.4, the packets go out, but they never
come back.

I'm obviously a confused soul. The manuals I have read have explained
the theory of TCP/IP, and I understand things, but how these things
are implemented, and how to make them work is obviously more difficult
than theorizing about them.

Thanks in advance if anyone can help me out.