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wfjm.w11/tools/oskit/doc/211bsd_ethernet.md
2022-08-20 08:37:33 +02:00

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Ethernet setup for 211bsd

Basic setup

The w11a uses an emulated DEUNA interface which interacts via a tap device with the Linux host system. The tap device in turn is usually connected to an internal bridge. This way the w11a can exchange packets with the Linux host as well as with any other node.

Setup of tap and bridge

The tap device should be created such that it is accessible by the account under with ti_w11 executes. This way only setting up tap and bridge require root access, but not subsequent usage.

Two support scripts help in the set up

    ip_create_br

creates a bridge named br0 and re-connects the physical ethernet interface. The script works on a PC with a single physical Ethernet interface.

    ip_create_tap [tap-name]

add a user-mode tap device to the bridge br0. If the bridge doesn't exist ip_create_br is called. If no name is given tap0 is used.

Used MAC addresses

The MAC addresses used by w11a are

    52:65:74:72:6f:??

which are in the range of locally administered MAC addresses. The first five bytes mean in ASCII "Retro", easy to pick out in tcpdump -xx traces.

Setup in ti_w11

Is contained in the boot tcl files, just three lines

    cpu0xua  set type deuna
    cpu0xua  set dpa  retro:00
    cpu0xua0 att tap:tap0

to select DEUNA emulation, the MAC address, and connect to tap0.

Setup in 211bsd

The current setup is very simple, expects to live in a 192.168.178.* subnet, and does not use DNS, /etc/resolv.conf is empty, uses only /etc/hosts

    127.0.0.1         localhost
    192.168.178.150   w11a
    192.168.178.20    athome

The parameters in /etc/netstart are

    hostname=w11a
    netmask=255.255.255.0
    broadcast=192.168.178.255
    default=192.168.178.1

Usage from 211bsd

Since name resolution is not yet activated and only the backend host athome is defined in /etc/hosts all other nodes must be specified by IP-Address, which can be inquired via nslookup

  ping athome
    PING athome (192.168.178.20): 56 data bytes
    64 bytes from 192.168.178.20: icmp_seq=0 ttl=64 time=40 ms
    64 bytes from 192.168.178.20: icmp_seq=1 ttl=64 time=20 ms

  ping 8.8.8.8
    PING 8.8.8.8 (8.8.8.8): 56 data bytes
    64 bytes from 8.8.8.8: icmp_seq=0 ttl=56 time=40 ms
    64 bytes from 8.8.8.8: icmp_seq=1 ttl=56 time=20 ms

  nslookup www.cern.ch 8.8.8.8
    Server:  google-public-dns-a.google.com
    Address:  8.8.8.8

    Non-authoritative answer:
    Name:    webrlb02.cern.ch
    Address:  188.184.9.235
    Aliases:  www.cern.ch
  
  telnet 188.184.9.235 80
    Trying...
    Connected to 188.184.9.235.
    Escape character is '^]'.
    GET / HTTP/1.0

    HTTP/1.1 302 Found
    Content-Type: text/html; charset=utf-8
    Location: http://home.web.cern.ch/
    Server: Microsoft-IIS/8.5
    X-Powered-By: ASP.NET
    Date: Thu, 30 May 2019 10:13:27 GMT
    Connection: close
    Content-Length: 141
    
    <html><head><title>Object moved</title></head><body>
    <h2>Object moved to <a href="http://home.web.cern.ch/">here</a>.</h2>
    </body></html>
    Connection closed by foreign host.

Usage from Linux

Simply use telnet:

  telnet 192.168.178.150
  Trying 192.168.178.150...
  Connected to 192.168.178.150.
  Escape character is '^]'.


  2.11 BSD UNIX (w11a)

  login: root
  erase, kill ^U, intr ^C
  #