Command Section
NOS-TUN(8)              FreeBSD 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]

     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
     ``'' on the cisco.  This is because the tunnel is a point-
     to-point interface in the FreeBSD end, a concept cisco does not really

     Protocol number sets tunnel mode.  Original KA9Q NOS uses 94 but many
     people use 4 on the worldwide backbone of

     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

           nos-tun -t /dev/tun0 -s -d

     Remote cisco on address

           interface tunnel 0
           ip address
           tunnel mode nos
           tunnel destination
           tunnel source

     The nos-tun utility appeared in FreeBSD 3.0.

     Nickolay N. Dudorov <[email protected]> wrote the program, Poul-Henning
     Kamp <[email protected]> wrote the man-page.  Isao SEKI <[email protected]>
     added a new flag, IP protocol number.

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

FreeBSD 11.1-RELEASE-p4         October 5, 2016        FreeBSD 11.1-RELEASE-p4
Command Section