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