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Old 03-06-2004, 12:55 PM   #1
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Registered: Mar 2004
Location: Germany
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Gateway problem, clients can't access some sites

Dear helpful people!

I recently set up my SuSE box to act as a Gateway/firewall to provide internet access to my clients (WinXp).
The problem is that the clients can't access a few internet sites, and even stranger is that most (all?) the sites I can't access are all from the same hosting company ( e.g., What i mean is, that after I type in the adress and hit ENTER, nothing happens, it just says "Wating for". I have tried both with Mozilla and Internet Explorer, and even stranger is that I can access the mentioned sites from the gateway/router without problem.

I read a similar thread just now and i tried (as they recommended) to disable the firewall (just using masq:ing), but it didn't solve anything.
Just using the MASQ:ing all I do is:
#All The lines below are NAT routing
# flush any old rules
$IPTABLES -F -t nat
# turn on NAT (IP masquerading for outgoing packets)
# enable IP forwarding (of incoming packets)
echo 1 > /proc/sys/net/ipv4/ip_forward

but like i said it still doesn't work.

Please let me know if you have any hints or ideas!!

My set up is:
SuSE 9.0, DSL connection (ppp0), and 3 NIC (only use 2 at the moment)

(another small problem (might be related): My connection seems to timeout after 15 minutes of inactivity eventhough I set the provider Idle_timeout to 0.
LCP terminated by peer
Setting MTU to 1492.
Couldn't increase MRU to 1500
Script /etc/ppp/ip-down finished

Feel free to help me with this as well...

Thanks in advance!!!

Old 03-06-2004, 03:12 PM   #2
Registered: Jun 2003
Posts: 132

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Hmm. weird things like this are hard to debug. Install something like ethereal on the gateway box and have it listen to all the traffic between you and one of those mystery sites. Is the request leaving your gateway properly? Is the site responding?

If its leaving and not coming back, it seems like its a problem with the remote site. If its not leaving, then you have weird problems with masquerading that I dont know how to debug if you're sure your firewall is completely disabled. If its leaving and coming back, then switch back to the inside network and see if you can catch the response returning to the PC that requested the site. If not, it may be that the site is mangling the packet in such a way that linux can't track down who had originally requested it.
Old 03-06-2004, 03:22 PM   #3
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Registered: Mar 2004
Location: Germany
Posts: 3

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Thanks a lot!
Will have a look a the traffic, thanks for the ethereal tip.

>>If its leaving and not coming back, it seems like its a problem with the remote site.
Seems weird, but like I said, since it applies to all sites of this ( hosting, could be that it is not my fault (I wish.

However, thanks for your reply!


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