[Wifidog] Looking at problems ahead

Tony Bussieres tonyicemanz at yahoo.ca
Wed Apr 21 07:40:17 EDT 2004

Can't we use the inittab functionnality to take care of that?

if we start wifidog in /etc/inittab, it will start wifidog at the device
boot up. And it will respawn the process automatically if the process

What do you think about it?


Btw, congratulations guys! You did a lot of work during the last week,
it's very exciting to see the project move that fast! 

On Tue, 2004-04-20 at 22:43, Philippe April wrote:
> Hi,
> While looking at the code and playing with WiFiDog on the WRT54G, I have
> found some issues I'd like to flag:
> 1. If WiFiDog segfaults, it will leave firewall rules behind (and of
> course, making the internet totally unaccessible).
>    To fix that, we can have a process that monitors our process (I'm not a
> fan, but hey). I think that will be a definite requirement.
>    Also, when we start WiFiDog, I'll need to write some iptables cleanup
> code to make sure there's no WiFiDog lying around.
>    Right now, WiFiDog inserts itself at line 1 of some chains (mouhahah)
> to make sure its rules are called before any other DENY. I will have to
> check and remove any rule left there.
>    So I need to make sure to clean any traces of WiFiDog, even if it's
> been started 60 times in a row and crashed all the times. I wish I
> could just scrap the firewall that's there, but I'd rather integrate.
> 2. The counters....
>    It's not super clean nor clear.
>    We call a shell script to get the counters. I found out the counters
> we're taking from the 'mangle' table is the upstream counter (which
> makes sense). To find out the "downstream", we'd have to insert a new
> chain in the FILTER table's chain FORWARD that gets called first and
> say "ACCEPT" to this destination IP.. And we all know we also want the
> downstream traffic.
>    That way, we get what traffic was destined for that host and we can
> count it.
>    Of course, to monitor all that, we could ask WiFiDog to call
> fw_counters and get the two counters for one particular IP address. If
> WiFiDog has to fork 20 times each time to get the values of the
> counters (iptables | grep | sed | awk, etc.... times 2), when we have
> 20 clients on a hotspot, the wrt54g won't keep up. Well, it probably
> will, but I'd rather make something more efficient than that.
>    Right now for counters, we go through one table (mangle, or the table
> that tags traffic per MAC address if you prefer).
>    We could just do as we do right now, but go through 2 places to find
> informations:
>    1. The mangle table - find which customers are still in the firewall,
> those not in that table definitely don't have access, so do a cleanup
> from linked list and other firewall tables.
>    2. The FORWARD chain - to get a nice table of the outgoing and incoming
> traffic for each individual.
>    I suggest we update all clients in the linked list, THEN make a
> decision on what to do with each client by going through the linked
> list (kill connection based on inactivity, based on "not in the
> firewall anymore", etc.) I think this would be the most efficient way
> to keep things clean. That way we can go through the list and find out
> which clients are not in the firewall (ie. their counters values were
> not found in the last check).
>    This is to make sure the linked list is in-sync with the firewall.
> Whee! Long email. Tell me what you think and if you have better ideas.
> Philippe
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May Linux be with you!

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