Route and “e” flag

Question

k# route -6
Destination                    Next Hop        Flag   Met  Ref   Use  If
::/0                           fe80::8001      UGDAe  1024 0     0    eth0
[...]

What does flag "e" mean?

Answer 1

It maps to RTF_EXPIRES. It means the route has a non-infinite lifetime. In this case, the kernel probably learned the route dynamically from a RA (Router Advertisement).

I recommend you use ip instead of route (and instead of ifconfig). Although it's Linux-specific and unportable, its syntax is much less archaic than the legacy commands. ip -6 route would even show you the actual amount of time before your route expires instead of just adding a e flag to say that it does.

Answer 2

The man page doesn't say...

But the route program comes from the net-tools package...

There's a git interface to the source here

which gives us the following information:

 UP U
 GATEWAY G
 REJECT !
 HOST H
 REINSTATE R
 DYNAMIC D
 MODIFIED M
 DEFAULT d
 ALLONLINK a
 ADDRCONF c
 NONEXTHOP o
 EXPIRES e
 CACHE c
 FLOW f
 POLICY p
 LOCAL l
 MTU u
 WINDOW w
 IRTT i
 NOTCACHED n

So it means expires.