Hundred of entries in ip route with GRE tunnel

[bolemo]

Hello,

I have recently installed OpenWrt, and I am using a GRE tunnel for all my connections (all LAN).

Here is how I set it up:
/etc/config/network

config interface ‘gretun’
	option proto 'gre'
	option peeraddr 'GRE_ENDPOINT'
	option mtu '1476'
	option ttl '12'
	option tunlink 'wan'
	option defaultroute '0'
	option delegate '0'

config interface ‘pub’
	option proto 'static'
	option device '@gretun'
	list ipaddr 'GRE_LOC_IP/30'
	list ipaddr 'GRE_PUB_IP/32'

config route
	option interface 'mwan'
	option proto 'static'
	option mtu '1476'
	option target '0.0.0.0/0'
	option gateway '0.0.0.0'
	option source 'GRE_PUB_IP/'

/etc/config/firewall

config nat
	option src 'mwan'
	option target 'SNAT'
	option snat_ip 'GRE_PUB_IP'
	option name 'MW-SNAT'
	list proto 'all'

---

It works fine, but I noticed something highly unusual and likely abnormal and unwanted.
My route tables is getting automatically flooded with any public IP being used in the tunnel:
root@OpenWrt:~# ip r

default dev gre4-pub scope link  src GRE_PUB_IP
IP #1 dev gre4-pub
IP #2 dev gre4-pub 
IP #3 dev gre4-pub
… 
IP #X dev-pub
…
IP #279 dev gre4-pub
IP #280 dev gre4-pub
WAN_PUB_SUBNET dev eth1 scope link  src WAN_PUB_IP
GRE_LOC_SUBNET dev gre4-pub scope link  src GRE_LOC_IP
GRE_ENDPOINT via WAN_PUB_GW dev eth1 
172.17.0.0/16 dev docker0 scope link  src 172.17.0.1 
LAN_SUBNET dev br-lan scope link  src LAN_ROUTER_IP

This is unessecary, because the first rule default dev gre4-pub scope link src GRE_PUB_IP is sufficient to route any traffic to the tunnel.
I have no idea what process or setting is responsible for the flood in the ip routing table.

Any clue on what I can do here? I have been working on this all day, without any success…

Thank you

[bolemo]

Nobody has any clue?

Would that be the normal behavior of OpenWrt in this situation?
Any idea on which process is dynamically adding all these (unecessary) routes?

[bolemo]

Found the problem!

After installing the package “ip-full” (hence not using the busybox version), I don’t see the hundred of extra routes and all appears as it should be.

So it is a bug in the busybox version of the ip utility.