IMPORTANT! Network is unreachable

Matthew Seaman m.seaman at
Sat Aug 9 12:22:41 UTC 2008

Andrew Snow wrote:
> Usually if there is more than IP in a given subnet on an interface, you 
> give it a /32 netmask.  Only the first IP in a subnet should have the 
> full netmask.
> So your example should look like this:
>     inet netmask 0xffffff00 broadcast
>     inet netmask 0xffffffff broadcast

/32 netmasks for 2nd and subsequent IP alias addresses used to be
mandatory and are arguably more correct, but nowadays you can use
the actual netmask for the network instead.  Was fixed a year or
two ago.  It's a wetware compatibility thing -- other unixoid OSes
never had the /32 netmask requirement, and it kept tripping people up
when swapping between OSes.

Unfortunately I can't say exactly what the problem the OP is experiencing
is due to, but the way routes are appearing and disappearing on a 5
minute timescale does suggest dynamic routing problems to me.  As a 
work-around, if the OP wanted to override the information routed gets
from the network, then he could use /etc/gateways to have the local
routed append some static routes to the routing table -- see routed(8)
for the gory  details.  Losing a route for a directly attached network
looks like a bug to me though.



Dr Matthew J Seaman MA, D.Phil.                   7 Priory Courtyard
                                                  Flat 3
PGP:     Ramsgate
                                                  Kent, CT11 9PW

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