EOIP(4) | Device Drivers Manual | EOIP(4) |
eoip
— MikroTik
Ethernet over IP tunnel network device
pseudo-device gre
The eoip
interface provides tunnelling of
Ethernet frames across IPv4 and IPv6 networks using the MikroTik Ethernet
over IP (EoIP) encapsulation protocol.
The protocol is based on the Generic Routing and Encapsulation (GRE) protocol. GRE datagrams (IP protocol number 47) consist of a GRE header and an outer IP header for encapsulating another protocol's datagram. The GRE header specifies a version and the type of the encapsulated datagram, allowing for the tunnelling of multiple protocols. EoIP uses GRE version 1, its own protocol identifier (0x6400) for Ethernet, and has its own keepalive semantics, making it distinct from the Ethernet over GRE version 0 protocol supported by egre(4). However, it is implemented as part of the same driver providing egre(4).
Different tunnels between the same endpoints are distinguished by a 16-bit tunnel identifier field in the header.
All GRE packet processing in the system is allowed or denied by setting the net.inet.gre.allow sysctl(8) variable. To allow GRE packet processing, set net.inet.gre.allow to 1.
eoip
interfaces can be created at runtime
using the ifconfig eoip
N
create
command or by setting up a
hostname.if(5) configuration file
for netstart(8).
For correct operation, encapsulated traffic must not be routed over the interface itself. This can be implemented by adding a distinct or a more specific route to the tunnel destination than the hosts or networks routed via the tunnel interface. Alternatively, the tunnel traffic may be configured in a separate routing table to the encapsulated traffic.
eoip
interfaces support the following
ioctl(2) calls for configuring tunnel
options:
SIOCSLIFPHYADDR
struct if_laddrreq *SIOCGLIFPHYADDR
struct if_laddrreq *SIOCDIFPHYADDR
struct ifreq *SIOCSVNETID
struct ifreq *SIOCGVNETID
struct ifreq *SIOCSLIFPHYRTABLE
struct ifreq *SIOCGLIFPHYRTABLE
struct ifreq *SIOCSLIFPHYTTL
struct ifreq *SIOCGLIFPHYTTL
struct ifreq *SIOCSLIFPHYDF
struct ifreq *SIOCGLIFPHYDF
struct ifreq *SIOCSTXHPRIO
struct ifreq *IF_HDRPRIO_PACKET
to specify that the current
priority of a packet should be used.SIOCGTXHPRIO
struct ifreq *SIOCSETKALIVE
struct ifkalivereq *Setting the keepalive period or count to 0 disables keepalives on the tunnel.
SIOCGETKALIVE
struct ifkalivereq *EoIP does not provide any integrated security features. It should only be deployed on trusted private networks, or protected with IPsec to add authentication and encryption for confidentiality. IPsec is especially recommended when transporting EoIP over the public internet.
The Packet Filter pf(4) can be used to filter tunnel traffic with endpoint policies pf.conf(5).
The Time-to-Live (TTL) value of a tunnel can be set to 1 or a low value to restrict the traffic to the local network:
# ifconfig eoipN tunnelttl 1
Host X ---- Host A ------------ tunnel ----------- MikroTik D --- Host E \ / \ / +------ Host B ------ Host C ------+
On Host A (OpenBSD):
# route add default B # ifconfig eoipN create # ifconfig eoipN tunnel A D # ifconfig eoipN up # route add E D
On Host D (MikroTik):
[admin@MikroTik] > interface eoip [admin@MikroTik] /interface eoip> add name="eoipN" \ \... local-address=D remote-address=A [admin@MikroTik] /interface eoip> enable eoipN
egre(4), inet(4), ip(4), netintro(4), options(4), hostname.if(5), protocols(5), ifconfig(8), netstart(8), sysctl(8)
S. Hanks, T. Li, D. Farinacci, and P. Traina, Generic Routing Encapsulation (GRE), RFC 1701, October 1994.
David Gwynne <dlg@openbsd.org>
December 5, 2020 | OpenBSD-current |