Macintosh HistoryPosts RSS Comments RSS

NSCA Telnet 2.5 FTP server connected with SLIP to the Internet

In my research on TCP/IP on Classic Macintosh I tried to run NSCA Telnet 2.6 and 2.5 on a minimal system equiped with only 512K. Without any succes…. To run it with System 6 and MacTCP is just to much.

But while trying I found something what triggered my interest. Unlike an older version I have (2.2), or newer version (2.6 and 2.7) NSCA Telnet 2.5 was capable of setting up a SLIP connection (Serial Line Internet Protocol) via a modem or serial cable. The 2.5 version is developed in june ’92, just before Internet got really big.
SLIP was a well know way of connecting to the Internet until the beginning of the ’90. It then was replaced by PPP which is ‘better engineered, has more features and does not require its IP address configuration to be set before it is established’.
So SLIP is an old way of setting up an Internet connection. It is very nice that NSCA has a SLIP client to set up a connection in its software.

For a SLIP connection you need:

  • A Macintosh with at least 1 MB RAM (Plus, SE or upgraded 512K)
  • A serial line; modem or null modem
  • NSCA Telnet 2.5
  • A SLIP provider, Linux/Unix box or OSX to connect your modem or null modem to
  • Install sliplogin on your Linux, Unix or OSX box

MacTCP should be in the System map. You should give it the IP address you want and what fits in your normal internal IP range, in my case The gateway is the Linux box, in my case
Maybe it works with NSCA own TCP stack… Didn’t tested it yet…. For that you have to edit the file in the same directory as the Telnet NSCA 2.5 program. If you don’t edit something it will need MacTCP.

There is a huge manual available. I make it available in PDF here:


In my setup I used my 512K which was upgraded to 1 MB. The serial line is an null modem cable I made myself (see for wiring). I connect this one to a Linux box. On the Linux box I installed sliplogin (sliplogin-2.1.1-3.i386.rpm for Red Hat in my case… but it is available for Mac OSX and other Linux )

Basicly you make a special user which is used to setup the SLIP connect. This user has no default shell but the program sliplogin. My /etc/passwd looks like this. Give this user a passwd and you can login.


Now only give the correct information about the IP address you will receive. This has to be done in /etc/slip/slip.hosts (or sometimes /etc/slip.hosts)

This is the only line I added:

stjaap normal            60

It means that when user stjaap logs in, the serial port on the server will get IP adres and the client (the Mac with NCSA 2.5 FTP server) Also correct subnet mask is given and a normal SLIP connection with a 60 seconds time out is set up.

If you login a special network device is setup, sl0. This has the same setup as an Ethernet card on a Linux box. You can route traffic true it, use ifconfig, etc.

See this picture:


Now we connect our Macintosh to the Linux box. My serial box allows a serial login. I added these line to /etc/inittab

s0:2345:respawn:/sbin/agetty -L 9600 ttyS0 vt100
s1:2345:respawn:/sbin/agetty -L 19200 ttyS1 vt100

I found out that my serial port on the Linux box that works is ttyS1

Start NSCA Telnet 2.5 and fire up your FTP server. That can be done under File /  FTP Enable.

Check your serial port settings. You can find them under Network / Serial Port Settings.

They should fit with your serial settings in /etc/inittab. In my case in /etc/inittab speed is 19200. Settings for NSCA Telnet 2.5 Serial Settings:

19200 baud
8 data bits
No parity
1 stop bit
Modem port
No handshaking
Open a connection under File / Open Connection and don’t fil in the two boxes Session Name and Window name. Only pick /select the little box before Serial/SLIP and click on OK.

If you are connected to a Linux box and you don’t see any prompt reboot your Linux box. After a while you will see the login prompt. Now login with your special SLIP user, in my case stjaap.
SLIP will be started and on the Linux box sl0 is setup.

Now you start an other connection in NSCA Telnet. This time you can enter a Session Name and Window name. Choose whatever you want or leave it empty as with the first connection. don’t  pick /select the little box before Serial/SLIP! Click om OK and you will see that the Session menu item is not greyed out any more. Select from this Session menu Switch to SLIP .
Now your FTP server is connected over the serial line with TCP/IP!
You could get a windows which says that it can find a certain server or gatway. Just click on it and it will go away. If you leave it open, no TCP/IP connection is possible and your server seems offline.


A ping from the Linux box and a FTP session

It means that a Macintosh can be an FTP server without an ethernet card or SCSI to Ethernet solution. It also means that you can do file sharing between other computers indepenant from operating system. If you don’t have any mac around you could exchange files like this.


No responses yet

Comments are closed.