Re: Wierd problem with irqs

["tanuki" <phake@sadomain.co.za>]

Hi 

thanx, didn't think of that . 
i'll try it and see what happens. 

still it is strange though

tanuki


----- Original Message ----- 
From: "George Alexandru Dragoi" <waruiinu@gmail.com>
To: "tanuki" <phake@sadomain.co.za>
Cc: <netfilter@lists.netfilter.org>
Sent: Wednesday, July 14, 2004 5:57 AM
Subject: Re: Wierd problem with irqs


> I think it is hardware related(well, DOH), which is causing large
> packets dropping. You could try sending ping of different packets
> size, and see when they begin to get dropped
> 
> 
> ----- Original Message -----
> From: tanuki <phake@sadomain.co.za>
> Date: Tue, 13 Jul 2004 15:56:19 +0200
> Subject: Wierd problem with irqs
> To: netfilter@lists.netfilter.org
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Hi all
> 
>  
> 
>  
> 
> had an interresting problem the other day, just 
> thought i'd share it with you all and see if 
> 
> any body else had a similar experience. 
> 
> 
>  
> 
>  
> 
> I set up a small nat/firewall box for a client of 
> ours. we had 5 interfaces and they were as follows 
> 
>  
> 
> eth0   192.168.10.1 netmask 
> 255.255.255.255 pointopoint 192.168.10.2   <--- adsl modem 
>  doing nat 
> 
> eth1   192.168.0.1 netmask 
> 255.255.255.0 
> 
> eth2   192.168.1.1 netmask 
> 255.255.255.0
> 
> eth3   192.168.2.1 netmask 
> 255.255.255.0
> 
> eth4    192.168.3.1 netmask 
> 255.255.255.255 pointopoint 192.168.3.2 <-- some upstairs router 
> 
> 
>  
> 
> and the routing table looked like you would expect 
> it to, with 
> 
>  
> 
> route add default gw 192.168.10.1 dev eth0 
> 
> 
>  
> 
> also we had 
> 
>  
> 
> echo "1" > /proc/sys/net/ipv4/ip_forward 
> 
> 
>  
> 
> for simplicity , iptables rules were as follows 
> 
> 
>  
> 
> iptables -t nat --append POSTROUTING -o eth0 --jump 
> MASQUERADE 
> 
>  
> 
> so, now all traffic using 192.168.0.1 , 1.1, 2.1 
> and 3.1 as a gateway should be able to reach the 
> 
> internet via the modem on 192.168.10.2 , right ? 
> 
> 
>  
> 
> well, all icmp worked, perfectly 
> 
>  
> 
> but everything else , ie , udp, tcp didn't 
> 
> 
>  
> 
> say for example http : packets get sent to tcp 80, 
> tcp replies get recieved, but no data gets back to 
> 
> the user on 192.168.whatever
> 
>  
> 
> strange huh ? 
> 
>  
> 
> so i thought my mtu was befuqed, so i do 
> 
> 
>  
> 
> iptables --append FORWARD --proto tcp --tcp-flags 
> SYN,RST SYN --jump TCPMSS --clamp-mss-to-pmtu 
> 
>  
> 
> no luck though. 
> 
>  
> 
> tried a plethora of other stuff too , but didn't 
> work, so i'll leave that there 
> 
>  
> 
> obviously the nat works, becuase all my icmp's are 
> natted. 
> 
> mmm
> 
>  
> 
> so i go into the boxes bios set up and tell it to 
> assign irq's to all pci devices automatically 
> 
>  
> 
> boot up into linux and do 
> 
>  
> 
> ifconfig eth4 up 
> 
>  
> 
> eth4: error fetching interface information: Device 
> not found
> 
> 
> eh ? wtf ? so i do 
> ifconfig eth0 up 
> 
>  
> 
> and the device gets brought up 
> 
>  
> 
> then i do ifconfig eth4 up 
> 
>  
> 
> and it brings it up . Strange huh ? 
> 
>  
> 
> so now i see that all my cards are swopped arround. 
> that which used to be eth0 is now eth4 and so 
> 
> on and so on. 
> 
>  
> 
> anyway, plug in the appropiate network cables to 
> the relevant nics and run the script 
> 
>  
> 
> to a ping to google.com ... everything works fine. 
> 
> 
> right, so far so good. right back were i 
> started
> 
>  
> 
> now, do a HTTP-GET http://www.google.com and guess what 
> 
> 
> i get a lovely html page. 
> 
>  
> 
> strange that changing the device irg assignment in 
> the bios solved my problem ? 
> 
>  
> 
> any ideas what could have caused this ? 
> 
> 
>  
> 
> thanks a lot for bearing with my idiotic ramblings 
> so far 
> 
>  
> 
> ----------------
> 
>  
> 
> tanuki
>