How to identify different ip tunnels
Date: Thu Jan 23 2014 - 02:33:27 EST
We want to identify different ip tunnels.
For example, we use “ip tunnel add xxx” command in linux to create an
ipv4/6 tunnel interface,then,we can receive a RTM_NEWLINK message from
linux for the new tunnel interface.
We will parse the struct ifinfomsg message and get the ifi->ifi_type
attribute. We need to do somethings depend on the tunnel type here.
I checked the linux source code and list all the tunnel types here:
#define ARPHRD_TUNNEL 768 /* IPIP tunnel */
#define ARPHRD_TUNNEL6 769 /* IP6IP6 tunnel */
#define ARPHRD_SIT 776 /* sit0 device - IPv6-in-IPv4 */
#define ARPHRD_IPGRE 778 /* GRE over IP */
It means that the linux will report the new link for any ipv4/6 tunnel
interface with type only within these four types. However, We need more
tunnel types for ipv4/6 tunnel.
For example, 4IN4/6IN4/6TO4/GRE/ISATAP for ipv4 tunnel and
4IN6/6IN6/IPIN6 for ipv6 tunnel.
Here are the result that we have got:
Actual Tunnel type ifi->ifi_type
So, we can NOT distinguish the actual tunnel type via ifi_type attribute
except the GRE4 and 4IN4 tunnel. However we need the actual type. That
is our question.
BTW, for the 6IN4 and 6TO4 tunnel, Can we distinguish them before the
interface ip address configured? Because we need to do different things
for them when we received the new link message and the tunnel has NOT
any ip address in this time.
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