1.\" Copyright (c) 1985, 1991, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" %sccs.include.redist.man% 5.\" 6.\" @(#)nsip.4 8.1 (Berkeley) 06/05/93 7.\" 8.Dd 9.Dt NSIP 4 10.Os BSD 4.3 11.Sh NAME 12.Nm nsip 13.Nd software network interface encapsulating NS packets in IP packets 14.Sh SYNOPSIS 15.Cd options NSIP 16.Fd #include <netns/ns_if.h> 17.Sh DESCRIPTION 18The 19.Nm nsip 20interface is a software mechanism which may be 21used to transmit Xerox 22.Tn NS Ns (tm) 23packets through otherwise uncooperative 24networks. 25It functions by prepending an 26.Tn IP 27header, and resubmitting the packet 28through the 29.Tn UNIX 30.Tn IP 31machinery. 32.Pp 33The super-user can advise the operating system of a willing partner 34by naming an 35.Tn IP 36address to be associated with an 37.Tn NS 38address. 39Presently, only specific hosts pairs are allowed, and for each host 40pair, an artificial point-to-point interface is constructed. 41At some future date, 42.Tn IP 43broadcast addresses or hosts may be paired 44with 45.Tn NS 46networks or hosts. 47.Pp 48Specifically, a socket option of 49.Dv SO_NSIP_ROUTE 50is set on a socket 51of family 52.Dv AF_NS , 53type 54.Dv SOCK_DGRAM , 55passing the following structure: 56.Bd -literal 57struct nsip_req { 58 struct sockaddr rq_ns; /* must be ns format destination */ 59 struct sockaddr rq_ip; /* must be ip format gateway */ 60 short rq_flags; 61}; 62.Ed 63.Sh DIAGNOSTICS 64.Bl -diag 65.It nsip%d: can't handle af%d. 66The interface was handed 67a message with addresses formatted in an unsuitable address 68family; the packet was dropped. 69.El 70.Sh SEE ALSO 71.Xr intro 4 , 72.Xr ns 4 73.Sh HISTORY 74The 75.Nm 76interface appeared in 77.Bx 4.3 . 78.Sh BUGS 79It is absurd to have a separate pseudo-device for each pt-to-pt 80link. 81There is no way to change the 82.Tn IP 83address for an 84.Tn NS 85host once the 86the encapsulation interface is set up. 87The request should honor flags of 88.Dv RTF_GATEWAY 89to indicate 90remote networks, and the absence of 91.Dv RTF_UP 92should be a clue 93to remove that partner. 94This was intended to postpone the necessity of rewriting reverse 95.Tn ARP 96for the 97.Xr en 4 98device, and to allow passing 99.Tn XNS 100packets through an 101Arpanet-Milnet gateway, to facilitate testing between some co-operating 102universities. 103