NOS-TUN(8)              FreeBSD System Manager's Manual             NOS-TUN(8)

NAME
     nos-tun - implement ``nos'' or ``ka9q'' style IP over IP tunnel

SYNOPSIS
     nos-tun -t tunnel -s source -d destination -p protocol_number [source]
             target

DESCRIPTION
     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.

EXAMPLES
     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:

           interface tunnel 0
           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

HISTORY
     The nos-tun utility appeared in FreeBSD 3.0.

AUTHORS
     Nickolay N. Dudorov <nnd@itfs.nsk.su> wrote the program, Poul-Henning
     Kamp <phk@FreeBSD.org> wrote the man-page.  Isao SEKI <iseki@gongon.com>
     added a new flag, IP protocol number.

BUGS
     We do not allow for setting our source address for multihomed machines.

FreeBSD 13.1-RELEASE-p6         October 5, 2016        FreeBSD 13.1-RELEASE-p6