1.\" $OpenBSD: eoip.4,v 1.8 2023/07/26 20:23:22 jmc Exp $ 2.\" $NetBSD: gre.4,v 1.10 1999/12/22 14:55:49 kleink Exp $ 3.\" 4.\" Copyright 1998 (c) The NetBSD Foundation, Inc. 5.\" All rights reserved. 6.\" 7.\" This code is derived from software contributed to The NetBSD Foundation 8.\" by Heiko W. Rupp <hwr@pilhuhn.de> 9.\" 10.\" Redistribution and use in source and binary forms, with or without 11.\" modification, are permitted provided that the following conditions 12.\" are met: 13.\" 1. Redistributions of source code must retain the above copyright 14.\" notice, this list of conditions and the following disclaimer. 15.\" 2. Redistributions in binary form must reproduce the above copyright 16.\" notice, this list of conditions and the following disclaimer in the 17.\" documentation and/or other materials provided with the distribution. 18.\" 19.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 20.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 21.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 22.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 23.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 24.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 25.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 26.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 27.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 28.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 29.\" POSSIBILITY OF SUCH DAMAGE. 30.\" 31.Dd $Mdocdate: July 26 2023 $ 32.Dt EOIP 4 33.Os 34.Sh NAME 35.Nm eoip 36.Nd MikroTik Ethernet over IP tunnel network device 37.Sh SYNOPSIS 38.Cd "pseudo-device gre" 39.Sh DESCRIPTION 40The 41.Nm 42interface provides tunnelling of Ethernet frames across 43IPv4 and IPv6 networks using the 44MikroTik Ethernet over IP (EoIP) encapsulation protocol. 45.Pp 46The protocol is based on the Generic Routing and Encapsulation (GRE) 47protocol. 48GRE datagrams (IP protocol number 47) consist of a GRE header 49and an outer IP header for encapsulating another protocol's datagram. 50The GRE header specifies a version and the type of the encapsulated datagram, 51allowing for the tunnelling of multiple protocols. 52EoIP uses GRE version 1, its own protocol identifier (0x6400) 53for Ethernet, and has its own keepalive semantics, 54making it distinct from the Ethernet over GRE version 0 protocol 55supported by 56.Xr egre 4 . 57However, it is implemented as part of the same driver providing 58.Xr egre 4 . 59.Pp 60Different tunnels between the same endpoints are distinguished 61by a 16-bit tunnel identifier field in the header. 62.Pp 63All GRE packet processing in the system is allowed or denied by setting the 64.Va net.inet.gre.allow 65.Xr sysctl 8 66variable. 67To allow GRE packet processing, set 68.Va net.inet.gre.allow 69to 1. 70.Pp 71.Nm 72interfaces can be created at runtime using the 73.Ic ifconfig eoip Ns Ar N Ic create 74command or by setting up a 75.Xr hostname.if 5 76configuration file for 77.Xr netstart 8 . 78.Pp 79For correct operation, encapsulated traffic must not be routed 80over the interface itself. 81This can be implemented by adding a distinct or a more specific 82route to the tunnel destination than the hosts or networks routed 83via the tunnel interface. 84Alternatively, the tunnel traffic may be configured in a separate 85routing table to the encapsulated traffic. 86.Ss Programming Interface 87.Nm 88interfaces support the following 89.Xr ioctl 2 90calls for configuring tunnel options: 91.Bl -tag -width indent -offset 3n 92.It Dv SIOCSLIFPHYADDR Fa "struct if_laddrreq *" 93Set the unicast IPv4 or IPv6 addresses for the encapsulating IP packets. 94The addresses may only be configured while the interface is down. 95.It Dv SIOCGLIFPHYADDR Fa "struct if_laddrreq *" 96Get the addresses used for the encapsulating IP packets. 97.It Dv SIOCDIFPHYADDR Fa "struct ifreq *" 98Clear the addresses used for the encapsulating IP packets. 99The addresses may only be cleared while the interface is down. 100.It Dv SIOCSVNETID Fa "struct ifreq *" 101Configure a virtual network identifier for use as the Tunnel Identifier. 102The virtual network identifier may only be configured while the 103interface is down. 104The Tunnel Identifier is a 16-bit value. 105.It Dv SIOCGVNETID Fa "struct ifreq *" 106Get the virtual network identifier used in the GRE Key header. 107.It Dv SIOCSLIFPHYRTABLE Fa "struct ifreq *" 108Set the routing table the tunnel traffic operates in. 109The routing table may only be configured while the interface is down. 110.It Dv SIOCGLIFPHYRTABLE Fa "struct ifreq *" 111Get the routing table the tunnel traffic operates in. 112.It Dv SIOCSLIFPHYTTL Fa "struct ifreq *" 113Set the Time-To-Live field in IPv4 encapsulation headers, or the 114Hop Limit field in IPv6 encapsulation headers. 115.It Dv SIOCGLIFPHYTTL Fa "struct ifreq *" 116Get the value used in the Time-To-Live field in an IPv4 encapsulation 117header or the Hop Limit field in an IPv6 encapsulation header. 118.It Dv SIOCSLIFPHYDF Fa "struct ifreq *" 119Configure whether the tunnel traffic sent by the interface can be 120fragmented or not. 121This sets the Don't Fragment (DF) bit on IPv4 packets, 122and disables fragmentation of IPv6 packets. 123.It Dv SIOCGLIFPHYDF Fa "struct ifreq *" 124Get whether the tunnel traffic sent by the interface can be fragmented 125or not. 126.It Dv SIOCSTXHPRIO Fa "struct ifreq *" 127Set the priority value used in the Type of Service field in IPv4 128headers, or the Traffic Class field in IPv6 headers. 129Values may be from 0 to 7, or 130.Dv IF_HDRPRIO_PACKET 131to specify that the current priority of a packet should be used. 132.It Dv SIOCGTXHPRIO Fa "struct ifreq *" 133Get the priority value used in the Type of Service field in IPv4 134headers, or the Traffic Class field in IPv6 headers. 135.It Dv SIOCSETKALIVE Fa "struct ifkalivereq *" 136Enable the transmission of keepalive packets to detect tunnel failure. 137Keepalives may only be configured while the interface is down. 138.Pp 139Setting the keepalive period or count to 0 disables keepalives on 140the tunnel. 141.It Dv SIOCGETKALIVE Fa "struct ifkalivereq *" 142Get the configuration of keepalive packets. 143.El 144.Ss Security Considerations 145EoIP does not provide any integrated security features. 146It should only be deployed on trusted private networks, 147or protected with IPsec to add authentication and encryption for 148confidentiality. 149IPsec is especially recommended when transporting EoIP over the 150public internet. 151.Pp 152The Packet Filter 153.Xr pf 4 154can be used to filter tunnel traffic with endpoint policies 155.Xr pf.conf 5 . 156.Pp 157The Time-to-Live (TTL) value of a tunnel can be set to 1 or a low 158value to restrict the traffic to the local network: 159.Bd -literal -offset indent 160# ifconfig eoipN tunnelttl 1 161.Ed 162.Sh EXAMPLES 163.Bd -literal 164Host X ---- Host A ------------ tunnel ----------- MikroTik D --- Host E 165 \e / 166 \e / 167 +------ Host B ------ Host C ------+ 168.Ed 169.Pp 170On Host A 171.Pq Ox : 172.Bd -literal -offset indent 173# route add default B 174# ifconfig eoipN create 175# ifconfig eoipN tunnel A D 176# ifconfig eoipN up 177# route add E D 178.Ed 179.Pp 180On Host D (MikroTik): 181.Bd -literal -offset indent 182[admin@MikroTik] > interface eoip 183[admin@MikroTik] /interface eoip> add name="eoipN" \e 184\e... local-address=D remote-address=A 185[admin@MikroTik] /interface eoip> enable eoipN 186.Ed 187.Sh SEE ALSO 188.Xr egre 4 , 189.Xr inet 4 , 190.Xr ip 4 , 191.Xr netintro 4 , 192.Xr options 4 , 193.Xr hostname.if 5 , 194.Xr protocols 5 , 195.Xr ifconfig 8 , 196.Xr netstart 8 , 197.Xr sysctl 8 198.Sh STANDARDS 199.Rs 200.%A S. Hanks 201.%A "T. Li" 202.%A D. Farinacci 203.%A P. Traina 204.%D October 1994 205.%R RFC 1701 206.%T Generic Routing Encapsulation (GRE) 207.Re 208.Sh AUTHORS 209.An David Gwynne Aq Mt dlg@openbsd.org 210