Apt-get install shorewall


















Also note we now have a new concept referred to as 'fw'. The fw entry simply means "me". It always refers to the Linux box shorewall is running on, and is completely independent of interfaces, ip addresses, or other network settings.

Notice that fw's type is 'firewall', not ipv4. It makes broad sweeps and big changes. Start here for designing security. Each line is processed from top to bottom for every packet that goes to or through the router. If a packet matches the source and the destination, then the policy type determines the fate of the packet. Ex: A device connected to the LAN tries to ping our firewall.

Rule 1 does not match, the destination is not the Internet. Rule 2 does match, source and destination are the same as our packet. The packet is sent on to its destination which just happens to be the firewall itself.

A device somewhere on the 'net' tries to ping our firewall. Rules do nothing, the source is not the Internet. Rule 5 does match. It is coming from the net. The destination does not matter. The packet is dropped, the person pinging us gets no response, as if our router is not turned on. A device connected to the LAN tries to ping google. Note: The "passing on" function usually needs to be configured in another file. The ping should then make it out to google.

When the packet comes back, it technically matches 'net to all DROP', but it is a response to a conversation we started. In the next article, we will walk through some more advanced topics, but there should be plenty here to get you started with for now.

As always, please have a look at the man pages for a more in-depth understanding. TecMint is the fastest growing and most trusted community site for any kind of Linux Articles, Guides and Books on the web.

Millions of people visit TecMint! If you like what you are reading, please consider buying us a coffee or 2 as a token of appreciation. We are thankful for your never ending support. May I know on which version of Linux distribution you are trying? In this article, I demonstrated how it would be configured over a two interface machine. Have a question or suggestion? Please leave a comment to start the discussion.

Please keep in mind that all comments are moderated and your email address will NOT be published. Save my name, email, and website in this browser for the next time I comment.

Notify me of followup comments via e-mail. You can also subscribe without commenting. This site uses Akismet to reduce spam. Learn how your comment data is processed. Install Shorewall Firewall in Linux In this multi-part tutorial, I am going to get you started with Shorewall , and walk you through some more advanced topics with this awesome firewall system.

What is Shorewall? The easiest way to install Shorewall on Debian, is to use apt-get. The user didn't read and follow the migration considerations in the release notes these are also reproduced in the Shorewall Upgrade Issues. Shorewall is designed to allow the default behavior of the product to evolve over time. To make this possible, the design assumes that you will not replace your current shorewall. If you feel absolutely compelled to have the latest options in your shorewall. You should determine which new options have been added and you must reset their value e.

If you try to upgrade using the wrong package, it probably won't work. If you are upgrading from a 2. Unfortunately, some distributions call this package iproute2 which will cause the upgrade of Shorewall to fail with the diagnostic:.

See if there are any incompatibilities between your configuration and the new Shorewall version and correct as necessary. If you already have Shorewall installed and are upgrading to a new version using the tarball:.

See above. The partial backup feature I added to Dachstein allows configuration data to be stored separately from the rest of the package. Once the config data is separated from the rest of the package, it's an easy matter to upgrade the package while keeping your current configuration in my case, just inserting a new CD and re-booting.

Users who aren't running with multiple package paths and using partial backups can still upgrade a package, it just takes a bit of extra work. The general idea is to use a partial backup to save your configuration, replace the package, and restore your old configuration files. Step-by-step instructions for one way to do this assuming a conventional single-floppy LEAF system would be:.

Make a backup copy of your firewall disk 'NEW'. This is the disk you will add the upgraded package s to. Format a floppy to use as a temporary location for your configuration file s 'XFER'. This disk should have the same format as your firewall disk and could simply be another backup copy of your current firewall.

That way, if anything goes wrong you can simply reboot off the OLD disk to get back to a working configuration. Use the lrcfg backup menu to make a partial backup of the package s you want to upgrade, being sure to backup the files to the XFER disk. From the backup menu:. Reboot your firewall using the NEW disk Reboot, verifying the firewall works as expected.



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