Path: utzoo!attcan!uunet!snorkelwacker!apple!escher From: escher@Apple.COM (Michael Crawford) Newsgroups: comp.sys.mac Subject: Re: NCSA Telnet questions Keywords: telnet Message-ID: <7644@goofy.Apple.COM> Date: 11 Apr 90 18:33:32 GMT References: <793@thebeach.UUCP> Organization: Apple Computer Inc., Cupertino, CA Lines: 154 In article <793@thebeach.UUCP> rich@cfi.COM () writes: >I want to use NCSA Telnet on our Mac/Sun Ethernet network, and have an >elementary question or two. As I understand it, I should be able to use Telnet >to create a remote login session on any of the Suns on our network. (We are >currently using a serial port connection and White Knight.) The Macs have >3-Com Etherlink/NB cards, and use Liaison as the Ethertalk/Appletalk bridge to >print on our QMS printer. They are also using TOPS to access each other's >files. > >What is the IP number I use for the Mac? I know the IP numbers for our 15 >Suns, but are the Macs supposed to have one? Can it be arbitrarily assigned? >I tried checking the "Assign Dynamically" button, but nothing happened (it >timed out). Are we lacking some daemon on the Suns? (There are 2 rarpd >daemons running on the two servers we have.) Is the "Default Host:" name the >name of the Sun machine where they will be logged into? > I believe the assign dynamically button only works when using a Kinetics Fastpath configured to serve a range of dynamic IP adresses. I am not sure but I think even that only works on the localtalk side. The simple answer is "ask your network administrator to do it for you". When I administrated a PC-NFS and Sun network, I impounded all the unused ether cards and PC-NFS software, so my users would have to come to me to get set up. That way I got it done right. Assuming you don't have one (or you are the Sysadmin!): There is a network part to your address, and a subnet part, and a host part. Net numbers whose first byte is in the range from 1-127 are class A, 128-191 are class B, and those above are class C. Class A addresses use the last 3 bytes for the host adress, B use the last two, C use the last one. The reason for the net/host adress split is for the recieving host to be able to tell whether the recieving host is on the same network (meaning same ethernet cable, or same token ring, or localtalk cable). If the net number is the same, then the sending host figures out the ether address of the recieving host, (using ARP), then sends it directly. If the net number is different, then the sending host forwards the packet to a router, and the router either sends it directly, or sends it on to another router. Two networks connected by a router is an "internet". The big internet that all the Universities, Military, and big comapanies are connected to is called "The Internet". The Internet is actually an internet composed of various internets called the NSFNet, Milnet, Cypress, etc. The ARPAnet was one of those networks; it is not around any more. Class A adresses allow you to have 16 million hosts on the same cable. Class C addresses allow only 256. If you want to have two cables, then you need to get another net number, which you have to get from the Network Information Center. A simple solution is to use subnets; here you get a net number, and subdivide it into subnets, where part of the original host field is made into the subnet number. The subnet mask tells the host what part of the adress to use for the net+subnet pair. Note that you can set it on any bit -- you can subnet class C addresses, so you could have two networks with 127 hosts each. Ask you administrator for a net address. This will be something like "90.70.0.14". Ask her for a subnet mask. Either you won't have one, or it will be something like "255.255.252.0". If you are the administrator, use an adress that is not already assigned to one of the hosts on your network. I'm not real hip on the address calculator of the MacTCP CDEV. What I usually do is enter the subnet mask using the slider. (This is reached by clicking the "more" button from the MacTCP CDEV. Then I click "OK", and type in the address as the admin gives it to you. If you do want to use the adress calculator, the subnet number uses the bits between the heavy black lines of the subnet mask slider. You will need to set the Class popup first, then set the slider, then enter your net number (128.1 is not #128, it is 32769). Enter the subnet number, then the node (or host) number. Single cable networks will usually not use a subnet mask; you only care if you are hooking up to another net. If you have a name server, you will need to ask who which machine it is on. The name server controls a domain. Enter the domain it controls, (apple.com for example), and its IP address. You may enter servers for other domains, as well. The default button is _your_ default domain. If you try to Telnet to goofy, then the domain which is the default will be tacked on to the host name, and the nameserver query will be "Who is goofy.apple.com" for example (your domain is certainly not apple.com!). If you do not have a name server, you will need to edit the file "hosts" which comes with MacTCP. Enter the IP adresses and names of the hosts on your internet there. There are brief instructions in the file. Look at the RFC mentioned in the file for more details. Networks that are not on the internet usually will not have a domain. They will need either a name server, or a hosts file. The file /etc/hosts on Unix will NOT work. It is not in the RFC-standard format. If you do not yet have a nameserver, set one up, it is worth it. Sun uses the Yellow Pages instead of name service; MacTCP does not use Yellow Pages. I believe suns can use Yellow Pages while providing name service. If you are using an internet, enter the IP adress of the gateway between your cable and the next in the gateway adress box. This will be the Kinetics box if you are on localtalk. Note that if you are on localtalk, you should configure your kinetics box so that the localtalk has a different net/subnet number than the ethertalk side. This is so hosts on the ethertalk side will know that the localtalk side uses smaller packets than they (ie. they will use the correct Maximum Transfer Unit).Kinetics allows you to run the localtalk cables as the same net number as the ether cable; the K box is assigned a range of node numbers that it is to serve on the localtalk. This makes the K box logically a bridge instead of a router, but it breaks because the ether hosts do not get the MTU right. You can set the IP adress from a bootp server by setting your ethernet address (look at your ethertalk card) in the file /etc/ethers, and your IP adress in the file /etc/hosts, on a Unix bootp server. I don't know much about bootp. It is possible for a network administrator to preconfigure all these options, and distribute locked copies of the CDEV to the users, where the users will just be able to enter their node adress (or not even that, if the node field is locked). A reasonable strategy is to decide ahead of time how many MacTCP hosts you expect to have; configure a driver for each of them on a boot floppy. Label the floppy with the IP adress it is configured for. When someone comes asking for an IP adress, give him the preconfigured floppy, and write down their name and phone number, Mailstop, etc, as well as their ethernet adress and the IP address you gave them. The best explanation for any of this is the book "Internetworking with TCP/IP", by Douglas Comer. Also, RTFM :-) Whew. Let me know if you have any trouble. -- Michael D. Crawford Oddball Enterprises 606 Modesto Avenue Santa Cruz, CA 95060 oddball!mike@ucscc.ucsc.edu Consulting for Apple Computer Inc. escher@apple.com Applelink: escher@apple.com@INTERNET# The opinions expressed here are solely my own.