summary on my previous post - "SSH connection problem"

[Peter Garrett]

On Fri, 12 Sep 2008 00:50:24 +0200
"Zhengguo Xu" <tworiversfolk at gmail.com> wrote:

> my problem is:
> i can connect from desktop to laptop but not reversely. in another word,
> desktop to laptop, ok. laptop to desktop, no connection.
> 
[snip]

> 11. "sudo iptables -L" on desktop:
> 
[snipped copious  iptables -L output from desktop ;-) ]

i haven't looked carefully at all those iptables rules, but I suspect
this might be where the problem lies.

What happens if you run the following commands in order, on the desktop?

sudo iptables -P INPUT ACCEPT
sudo iptables -P OUTPUT ACCEPT
sudo iptables -P FORWARD ACCEPT

sudo iptables -F    # Comment (flushes all existing iptables chains)

This should give you a totally "open" firewall on the desktop, and thus
you should be able to reach sshd from the laptop. After those commands
the output from "sudo iptables -L" on both laptop and desktop should
look like the output below from your laptop.

> however, on laptop the same command has output:
> 
> Chain INPUT (policy ACCEPT)
> target     prot opt source               destination
> 
> Chain FORWARD (policy ACCEPT)
> target     prot opt source               destination
> 
> Chain OUTPUT (policy ACCEPT)
> target     prot opt source               destination
> 
> 
> it seems empty. is it normal?

"Normal" in the sense that this is the output expected when no
iptables / firewall  rules are in operation, yes.

I suspect that running the commands I listed above will enable you to
connect from laptop to desktop. If so, then the firewall/iptables
configuration on your desktop is at fault. It's worth a try anyway :)

You can always restore your firewall / iptables settings, if this does
not succeed.

Peter

-- 
"INX Is Not X" Live CD based on Ubuntu 8.04 : http://inx.maincontent.net
Screenshots slideshow: http://inx.maincontent.net/album/1.png.html
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 189 bytes
Desc: not available
URL: <https://lists.ubuntu.com/archives/ubuntu-users/attachments/20080915/51b8d8b1/attachment.sig>