[pups] Networking With 2.11 BSD and Begemot Emulator

Steven M. Schultz sms at moe.2bsd.com
Wed Oct 4 10:11:10 AEST 2000

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

	In /etc/netstart on the 11 side just after the 'ifconfig' lines:

	ifconfig qe0 inet netmask $netmask $hostname broadcast $broadcast up -trailers >/dev/console 2>&1
	# ifconfig sl0 inet -arp -trailers >/dev/console 2>&1
	# slattach /dev/ttyS6 9600
	# Next line needed when running under the Begemot emulator
	arp -s "0:0:c:3d:e9:f7" pub
	arp -s "0:a0:24:78:9c:21" pub
 	arp -s "0:90:27:88:64:74" pub
 	arp -s "08:0:2b:f:5b:a6" pub
	arp -s "0:40:5:a4:72:27" pub
	ifconfig lo0 inet localhost up -trailers	>/dev/console 2>&1

	Typically you only need the ARP info for the hosting system and
	the default gateway.   

	Oh, there's a bug in P11 that after 25 days of calendar up time the
	clock on the 11 basically stops ticking.   I've a fix I came up with
	(and submitted to the author) but it'll be a couple weeks until I
	know for sure if it's the right fix (32bit overflow in a calculation).

	Steven Schultz
	sms at to.gd-es.com

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