ipt -P INPUT ACCEPT problem

ipt -P INPUT ACCEPT problem

[BTP]

Hello,

This is my first time posting here and I have a problem with some basics.

I have a personal laptop running Debian sitting behind a linksys
future-shop-bought router that nicely provides me with DHCP services
at boot. My only concern at the moment is having iptables as a basic
firewall that can block/accept all incoming and outgoing packets from
my untrustworthy router.

Starting out to experiment, I wanted to block all incoming packets:

iptables -P INPUT DROP

Then, I wanted to undo my changes:

iptables -P INPUT ACCEPT

Why is it that now I can't access the internet? I can access my router
at 192.168.1.1 and my other system at 192.168.1.100 but everythign
else is just shut down. Checking my router setup turns out that it
assigned only one DHCP client, and my system is gone from its list.

Is there something about the internal workings of iptables I should
know, or is this meant for the Debian, or general Linux help mailing
list?? I attempted restarting my networking scripts but it failed on
DHCP init.

Bart

RE: ipt -P INPUT ACCEPT problem

[Rob Sterenborg]

> I have a personal laptop running Debian sitting behind a linksys
> future-shop-bought router that nicely provides me with DHCP services
> at boot. My only concern at the moment is having iptables as a basic
> firewall that can block/accept all incoming and outgoing packets from
> my untrustworthy router. 
> 
> Starting out to experiment, I wanted to block all incoming packets:
> 
> iptables -P INPUT DROP
> 
> Then, I wanted to undo my changes:
> 
> iptables -P INPUT ACCEPT
> 
> Why is it that now I can't access the internet? I can access my router

We don't know. Show us the output of "iptables -nvL".

> at 192.168.1.1 and my other system at 192.168.1.100 but everythign
> else is just shut down. Checking my router setup turns out that it
> assigned only one DHCP client, and my system is gone from its list.

What does "ifconfig" say ? Maybe you have to renew your DHCP lease.
Perhaps the router doesn't accept your IP if it's not in it's list.

> Is there something about the internal workings of iptables I should
> know, or is this meant for the Debian, or general Linux help mailing
> list?? I attempted restarting my networking scripts but it failed on
> DHCP init. 

Unless you received an error when executing the commands above, there
should be no problem. Maybe it's something with the router ; there's not
too much troubleshooting information.


Gr,
Rob

Re: ipt -P INPUT ACCEPT problem

[ludi]

You should be sure whether the problem is a network-connection error.

Re: ipt -P INPUT ACCEPT problem

[BTP]

I dont know what the problem was, things seem to work now without
issues. Maybe last time I might have broken something as it's likely I
set/unset since it was my first time starting to mess with iptables
with a script.

Thanks for the replies though.

Bart

> > Is there something about the internal workings of iptables I should
> > know, or is this meant for the Debian, or general Linux help mailing
> > list?? I attempted restarting my networking scripts but it failed on
> > DHCP init.
>
> Unless you received an error when executing the commands above, there
> should be no problem. Maybe it's something with the router ; there's not
> too much troubleshooting information.
>
>
> Gr,
> Rob
>
>
>