1.\" 2.\" ---------------------------------------------------------------------------- 3.\" "THE BEER-WARE LICENSE" (Revision 42): 4.\" <phk@FreeBSD.org> wrote this file. As long as you retain this notice you 5.\" can do whatever you want with this stuff. If we meet some day, and you think 6.\" this stuff is worth it, you can buy me a beer in return. Poul-Henning Kamp 7.\" ---------------------------------------------------------------------------- 8.\" 9.\" $FreeBSD$ 10.\" 11.Dd October 5, 2016 12.Dt NOS-TUN 8 13.Os 14.Sh NAME 15.Nm nos-tun 16.Nd implement ``nos'' or ``ka9q'' style IP over IP tunnel 17.Sh SYNOPSIS 18.Nm 19.Fl t 20.Ar tunnel 21.Fl s 22.Ar source 23.Fl d 24.Ar destination 25.Fl p 26.Ar protocol_number 27.Op Ar source 28.Ar target 29.Sh DESCRIPTION 30The 31.Nm 32utility is used to establish an 33.Em nos 34style tunnel, (also known as 35.Em ka9q 36or 37.Em IP-IP 38tunnel) using a 39.Xr tun 4 40kernel interface. 41.Pp 42.Ar Tunnel 43is the name of the tunnel device 44.Pa /dev/tun0 45for example. 46.Pp 47.Ar Source 48and 49.Ar destination 50are the addresses used on the tunnel device. 51If you configure the tunnel against a cisco router, use a netmask of 52.Dq 255.255.255.252 53on the cisco. 54This is because the tunnel is a point-to-point interface 55in the 56.Fx 57end, a concept cisco does not really implement. 58.Pp 59.Ar Protocol number 60sets tunnel mode. 61Original KA9Q NOS uses 94 but many people use 4 62on the worldwide backbone of ampr.org. 63.Pp 64.Ar Target 65is the address of the remote tunnel device, this must match the source 66address set on the remote end. 67.Sh EXAMPLES 68This end, a 69.Fx 70box on address 192.168.59.34: 71.Bd -literal -offset indent 72nos-tun -t /dev/tun0 -s 192.168.61.1 -d 192.168.61.2 192.168.56.45 73.Ed 74.Pp 75Remote cisco on address 192.168.56.45: 76.Bd -literal -offset indent 77interface tunnel 0 78ip address 192.168.61.2 255.255.255.252 79tunnel mode nos 80tunnel destination 192.168.59.34 81tunnel source 192.168.56.45 82.Ed 83.Sh HISTORY 84The 85.Nm 86utility appeared in 87.Fx 3.0 . 88.Sh AUTHORS 89.An -nosplit 90.An Nickolay N. Dudorov Aq Mt nnd@itfs.nsk.su 91wrote the program, 92.An Poul-Henning Kamp Aq Mt phk@FreeBSD.org 93wrote the man-page. 94.An Isao SEKI Aq Mt iseki@gongon.com 95added a new flag, IP protocol number. 96.Sh BUGS 97We do not allow for setting our source address for multihomed machines. 98