hi,

i have an server, an wireless access point and a wireless network card on the server
server is few switches away from me

now ! i want server to work with wired connection, but in the case i have lan connection fail (server is in another building) i would like to be able to enter server via wireless connection (wireless access point is close to me) and do some debugging (or something)

but, the problem is that be cause both wired and wireless connections are on the same LAN (i use access point for other wireless connections, so i cannot make it dedicated only to this backup access to server) seems like that without any reason server is start using wireless connection instead of wired one

i tried to put a different subnet on wireless, i tried to change metrics in routing table, still the same problem

my guess is what i need is to change interfaces metrics ... but ...

I CANNOT CHANGE INTERFACES METRICS IN ... LINUX !

this is really and i mean REALLY incredible by itself, i can do that just fine in windows,
ifconfig even have the metric option, can display the metrics of interfaces but refuse to change them with the error: "SIOCSIFMETRIC: Operation not supported", and that is about linux generally, not driver or anything be cause it don't work on any interface (wired, wireless, or even loopback)

after reading Setting metric for eth interfaces?
i tried ifmetric ... this program is not reporting anything of what it does ! (if it does anything at all), it cannot show/list metrics of interfaces in the system and according to ifconfig no metric is changed (all interfaces metrics remains set to 1 no matter what i do)

so ! any ideea for my problem or/and (i'm curios REALLY about this) how to set metrics on network connections in linux ?

Hi,

My thoughts about it would be like:
- configure Wifi card to be disabled at boot (ONBOOT=no), leaving LAN on -- so it should connect through LAN
- checking with some kind of script (if possible) if LAN is out then enable Wifi otherwise disable it again (ifup, ifdown)

How to do it is not in my ability, but maybe it's acceptable for you to investigate it further...


good luck

if you have two nic's, they each have their own ip address. Why not just have all network traffic point to eth0 and, if it goes down, use the alternate wlan0 ip. If it's all traffic that needs to use this setup, the only [modern] routing protocols I know of that use a metric other than hops (for a small network) are ospf and eigrp. So I don't believe metric will help unless you have more hops using wireless and are using rip or rip v2.

your server by default is probably load balancing since you have set up a form of link aggregation.

thank you for your answers !

i need both connections on server to work in the same time
server is closer to internet router than me

it means that i can lose connection to wired but not the server ...

also ! server switching against all odds, all by itself default working connection (default gateway is set up on a different interface) is something i still believe can be fixed with metrics