Virtual Interfaces in Linux

Table of contents

1. Revision history
2. Meaning and how to create various types of virtual interfaces on Linux

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Revision history

	Revision	Date	Remark
	0.1	Feb-02-2023	Add Document
	0.2	Feb-02-2023	Add description of Docker using VETH
	0.3	Feb-04-2023	Add tunnel interface
	0.34	Feb-06-2023	Add ipvlan interface

Meaning and how to create various types of virtual interfaces on Linux

Type	How to create	Meaning
Bridge	Create interface brctl addbr br0 ip link add name br0 type bridge Delete interface brctl delbr br0 ip link delete br0 Add interface to bridge brctl addif br0 eth1 ip link set eth1 master br0 Remove interface from bridge brctl delif br0 eth1 ip link set eth1 nomaster	Software bridge, L2 interface
802.1Q VLAN	Check if kernel is enabled modinfo 8021q Create interface vconfig add eth1 8 ip link add link eth1 name eth1.8 type vlan id 8	802.1Q VLAN interface, L2 interface
MACVLAN	Create interface ip link add macvlan1@eth0 link eth0 type macvlan mode bridge	MACVLAN interface, Interface needs to support promiscuity mode, L2 interface
IPVLAN	Create interface ip link add ipvlan1@eth0 link eth0 type ipvlan mode l2	Similar to macvlan, ipvlan supports L2 and L3. In L2 mode, interfaces have the same MAC but different IPs
TUN	Create interface ip tuntap add name tun0 mode tun	- Only accepts L3 packets - Cannot be added to bridge - Cannot broadcast packets - Commonly used for VPN connections
TAP	Create interface ip tuntap add name tap0 mode tap	- Operates at L2 - Can be added to bridge - Can broadcast packets - Commonly used in virtual machine systems
VETH	Create interface ip link add veth1 type veth peer name veth2	- Creates a pair of virtual interfaces with link connection to each other - Docker bridge mode uses this config, veth0 is bound to container, veth1 is added as member of bridge docker0
TUNNEL	Create interface ip tunnel add tunnel0 mode sit ttl $TUNTTL remote $ISPBRIP local $WAN4IP Delete interface ip tunnel del tunnel0	- Create tunnel interface, modes: ipip | gre | sit | isatap | vti | ip6ip6 | ipip6 | ip6gre | vti6 | any