Tag Archives: shorewall

Transparent Squid Proxy

Over the holidays, I had a user experience and attempted browser hijacking.  It appeared to have bypassed my squid proxy.   My updated configuration now sends all web access via squid.  The old firewall rules, that allowed direct access to the Internet, have been replaced with a transparent Squid proxy.  This runs on my existing Squid Proxy using another port. Continue reading

Implementing IPv6 6to4 on OpenWRT

As the IPv4 addresses begins to run out I finally invested the time to investigate and implement IPV6. As my ISP has not yet announced availability of IPV6 addresses I chose to implement a 6to4 tunnel. This is simple to implement, and currently well supported. My external firewall is an ASUS wireless router running OpenWRT.  As I have a static IP address, my implementation is simpler than is required by a dynamic address.  Support for dynamic IPv4 addresses is not covered here, but this configuration should work as long as your address does not change.

I initially created a 6to4 implementation without a firewall.  Then to secure my systems I implemented a firewall using Shorewall6-lite.  Until I figured out how to configure the 6tunnel script, I used the command line to bring up the network.  This documentation uses of the 6tunnel script instead of the manual commands.  My configuration does not yet include any IPsec functionality. Continue reading

Manual networking for KVM

I found the networking configured by libvirt (KVM) did not allow me to firewall the network as I desired.  I use Shorewall for firewalling, and DNSMasq for internal DNS and DHCP.  After a little experimentation, I found that I could configure Ubuntu to create the network.  This allows me to get a reliable firewall configuration with a virtual DMZ.

The virtual hosts are assigned to a bridge, and only have connectivity to other networks as defined in the Shorewall configuration.  A single DNSMasq server provides DSN an DHCP services for all virtual servers, as well as the network the server is connected to.  The network and firewall configuration remains consistent even as servers are cycled up and down.  An additional bridge was created to support virtual servers in the DMZ zone. Continue reading

Firewalling Google Chat and Skype

To enable for Internet chat I set up Google Chat and Skype.  My firewall rules have been extremely restrictive with only known and approved services allowed to connect.  Google Chat installed with no noticeable impact to the firewall. Things did not go so well with Skype.

The installation of Skype resulted in lots of warnings on the firewall.  Outgoing tests worked with only port 80 and 443 open.  Skype’s peer-to-peer approach  requires at least one port be opened incoming and and a large range of ports outgoing.  They specify all ports over 1024 should be open.  Their preferred mode seems to be to use uPnP to dynamically modify the firewall.   They do allow you to attempt to set  fixed incoming port which is also used for some outgoing UDP traffic. Continue reading