Effects of shutting down intreface/ipfirewalls

Hello,

I'm trying to figure out what happens to "in transit" packets as
they're passed down from the application layer to the lower layers when
an interface is shut down or when an iptable rule blocks the intended
destination.

What happens to the packets (queued or dropped) for the two situations?
Or does anyone have any pointers on how to find out?
.nathan.

In article <(E-Mail Removed). com>,
(E-Mail Removed) wrote:

>I'm trying to figure out what happens to "in transit" packets as
>they're passed down from the application layer to the lower layers when
>an interface is shut down or when an iptable rule blocks the intended
>destination.

Try it.

[compton ~]$ telnet spitzer
Trying 192.168.1.61...
telnet: Unable to connect to remote host: No route to host
[compton ~]$

That would happen if the either network interface goes down, or if the
firewall rules are 'DROP', Here, 'spitzer' is off-line for a new hard
drive at the moment. If the network is up on both, and either firewall
is 'REJECT' you see

[compton ~]$ telnet chandra
Trying 192.168.1.68...
telnet: Unable to connect to remote host: Connection refused
[compton ~]$

>What happens to the packets (queued or dropped) for the two situations?

In the first case above, the packets are queue, then the error message occurs
In the second case, the error occurs almost immediately.

>Or does anyone have any pointers on how to find out?

Try it as above. For added points, use a packet sniffer, like tcpdump, and
watch what happens.

Old guy