[pups] Networking With 2.11 BSD and Begemot Emulator

[Greg Lehey]

On Tuesday,  3 October 2000 at 17:11:10 -0700, Steven M. Schultz wrote:
> Hi --
>
>> From: Frank Wortner <frank at wortner.com>
>>
>> I've been trying to set up an emulated PDP-11 running 2.11 BSD.  Just for
>> the fun,  I'm trying to get the 11 to talk on a LAN.  Unfortunately,  it's...
>>
>> My configuration is Begemot P11 Version 2.7 running under
>> FreeBSD 4.1.1.  I've booted 2.11,  configured a custom networking kernel,
>> installed the unix and netnix images,  changed the IP addresses in...
>>
>> 	ifconfig tun0 host-IP-address emulator-IP-address up
>>
>> # ifconfig tun0
>> tun0: flags=8051<UP,POINTOPOINT,RUNNING,MULTICAST> mtu 1518
>>         inet6 fe80::260:8ff:febd:5882%tun0 --> :: prefixlen 64 scopeid 0xb
>>         inet host-IP-address --> emulator-IP-address netmask 0xffff0000
>>         Opened by PID 32199
>>
>> The IP addresses are identical in the first three octets,  and differ only
>> in the last octet.
>>
>> Unfortunately,  once I boot 2.11 BSD,  I can't contact the "outside
>> world" from the emulator,  nor contact the emulator from the
>> outside.  No telnet,  no ftp,  pings just hang.
>> What am I missing?
>
> 	You're missing ARP.
>
> 	'tun' only works with IP - ARP packets are not IP and do not pass
> 	thru the 'if_tun' driver.
>
> 	I have (using BSD/OS 4.1's if_tun which is probably the same as
> 	FreeBSD's) an emulated 11 going quite nicely.
>
> 	What you need to do ON THE 11's SIDE, is populate his arp table with
> 	the information about any host on the local LAN that the 11 will
> 	want to talk to

I didn't need to do this when I had the emulated net running.  I did
set the netmask to 255.255.255.255, though, and put the default route
through that interface.

Greg
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