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I'm trying to set up a proxy server on an Ubuntu Box, but my linux-fu is pretty weak and I'm stymied with an iptables issue.

I'm trying to execute this command:

iptables -A INPUT -d -p tcp -m –dport 443 -j ACCEPT

The error I get back is this:

iptables v1.4.4: Couldn't load match `-dport':/lib/xtables/ cannot open shared object file: No such file or directory

Try `iptables -h' or 'iptables --help' for more information.

There is, in fact, no file with that name.

iptables was not installed on my machine, I did:

apt-get install iptables

to install it. Finally, here's my distro info:


Any idea what's going on? If this is an obvious question, please point me to the relevant documentation; I'm kinda lost on even where to look, and Googling pulls up nothing.



share|improve this question
Are you sure you typed the command correctly as posted here? The dport option should be written as --dport. – Khaled Jan 23 '12 at 15:35
You're right, I was missing the dash. However, I still get an error. I've updated my error message above. – scottlabs Jan 23 '12 at 15:41
I see that this error can happen when you write the command with missing tcp after -m. – Khaled Jan 23 '12 at 15:43
Hi Khaled, I'm not sure I follow. Can you perhaps paste the command with tcp in the right place? I don't really follow. – scottlabs Jan 23 '12 at 15:47
I think you issued the command as: iptables -A INPUT -d -p tcp -m -dport 443 -j ACCEPT. – Khaled Jan 23 '12 at 15:52
up vote 1 down vote accepted

You should enter the command as follows:

$ sudo iptables -A INPUT -d -p tcp -m tcp --dport 443 -j ACCEPT

Pay attention to the protocol name after -m and double dash before dport. You can also remove -m tcp from the above command as it is useless in your command.

share|improve this answer
thanks, that worked! – scottlabs Jan 23 '12 at 16:20

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