NOS-TUN(8) MidnightBSD System Manager’s Manual NOS-TUN(8)
nos-tun — implement ‘‘nos’’ or ‘‘ka9q’’ style IP over IP tunnel
nos-tun −t tunnel −s source −d destination −p protocol_number [source] target
The nos-tun utility is used to establish an nos style tunnel, (also known as ka9q or IP-IP tunnel) using a tun(4) kernel interface.
Tunnel is the name of the tunnel device /dev/tun0 for example.
Source and destination are the addresses used on the tunnel device. If you configure the tunnel against a cisco router, use a netmask of ‘‘255.255.255.252’’ on the cisco. This is because the tunnel is a point-to-point interface in the FreeBSD end, a concept cisco does not really implement.
Protocol number sets tunnel mode. Original KA9Q NOS uses 94 but many people use 4 on the worldwide backbone of ampr.org.
Target is the address of the remote tunnel device, this must match the source address set on the remote end.
This end, a FreeBSD box on address 192.168.59.34:
nos-tun -t /dev/tun0 -s 192.168.61.1 -d 192.168.61.2 192.168.56.45
Remote cisco on address 192.168.56.45:
ip address 192.168.61.2 255.255.255.252
tunnel mode nos
tunnel destination 192.168.59.34
tunnel source 192.168.56.45
Nickolay N. Dudorov 〈firstname.lastname@example.org〉 wrote the program, Poul-Henning Kamp 〈phk@FreeBSD.org〉 wrote the man-page. Isao SEKI 〈email@example.com〉 added a new flag, IP protocol number.
We do not allow for setting our source address for multihomed machines.
MidnightBSD 0.3 April 11, 1998 MidnightBSD 0.3