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-   -   Firewall/Router/pppoe/dhcp (http://www.linuxquestions.org/questions/linux-networking-3/firewall-router-pppoe-dhcp-92166/)

Beetle B. 09-12-2003 07:36 PM

Firewall/Router/pppoe/dhcp
 
Hi,

I got DSL a week ago, and had it hooked up to my Linux box (Gentoo). Everything was fine - the protocol was pppoe, and I ws using rp-pppoe. Real Player, for example, worked fine. Then a few days later, my roommate got a router, and we hooked his computer and mine to it.

So now the DSL connection from the phone jack goes to the router, which uses PPPoE for the DSL. Each computer, however, uses DHCP to connect to the router.

Now I can't access Real Player, and some other programs suggest a firewall. My roommate, though, can access everything using his Windows box.

The firewall on the router is disabled .
I don't have ipchains installed.
I have iptables installed, and tried running it once, but it wasn't compiled into my kernel - I'm assuming that isn't active either.

As my roommate can access everything, I assume neither the router nor the ISP is at fault.

So 1) Other than ipchains and iptables, could I have some other firewall installed on my Linux machine. I installed quite a lot of packages right after getting DSL - could one of them inadvertently have installed a firewall?

2) If the above is not the case - my next guess is the move from PPPoE to DHCP. Could the sudden change create such problems?

Thanks,

/bin/bash 09-13-2003 04:48 AM

I'm sure your ISP is only giving you one IP address, so is your roomates router setup to do IP-Masquerading?
What does ifconfig tell you?
Do you have an IP?
What about route?
Is there a default route to the router?
Can you ping the router?
Can you ping the windows computer? or versa-visa?

Just a few things you can check.

Beetle B. 09-13-2003 01:29 PM

Quote:

I'm sure your ISP is only giving you one IP address, so is your roomates router setup to do IP-Masquerading?
Frankly, I have no idea (I'm new to these concepts). I looked on the router, and didn't find an option for it.

Quote:

What does ifconfig tell you?
eth0 Link encap:Ethernet HWaddr 00:E0:18:D9:ED:2A
inet addr:192.168.2.51 Bcast:255.255.255.255 Mask:255.255.255.0
UP BROADCAST NOTRAILERS RUNNING MULTICAST MTU:1500 Metric:1
RX packets:1202518 errors:0 dropped:0 overruns:0 frame:0
TX packets:909910 errors:0 dropped:0 overruns:0 carrier:910443
collisions:0 txqueuelen:100
RX bytes:1487060570 (1418.1 Mb) TX bytes:123000245 (117.3 Mb)
Interrupt:11 Memory:de000000-de001080

lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
UP LOOPBACK RUNNING MTU:16436 Metric:1
RX packets:154994 errors:0 dropped:0 overruns:0 frame:0
TX packets:154994 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:53686749 (51.1 Mb) TX bytes:53686749 (51.1 Mb)

Quote:

Do you have an IP?
The ISP gives an IP (dynamic, I believe), and the router assigns one to each computer.

Quote:

What about route?
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
192.168.2.0 * 255.255.255.0 U 0 0 0 eth0
loopback localhost 255.0.0.0 UG 0 0 0 lo
default 192.168.2.1 0.0.0.0 UG 0 0 0 eth0

(last one being the router). Not sure what the first one is.

Quote:

Is there a default route to the router?
How do I check?

Quote:

Can you ping the router?
Yes.

Quote:

Can you ping the windows computer? or versa-visa?
I can ping him - haven't tried the other way round (he's not in right now).

One funny thing. When we installed the router, we could go to it's page and see both our computers listed as connected. Now, for some reason, it only shows mine (even though I can ping him, and he can surf). In fact, I can even share files with him using Samba.

camelrider 09-15-2003 02:07 PM

How about the contents of /etc/resolv.conf?
When you were directly connected to the DSL modem the DNS's ip may have been supplied by the ISP each time you connected, making temporary information in /etc/resolv.conf.
If you can get the DNS iIP's off your buddy's box try entering them into /etc/resolv.conf like:
nameserver xx.xx.xx.xx
nameserver yy.yy.yy.yy


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