A dedicated drop device is a network appliance, usually a router or L3 switch that sites at the very edge of your network infrastructure. Beyond the firewall, and usually acts a as either layer 2 or 3 transit devices for your ISP interconnect uplinks for public or untrusted segments. Distinguishing a dedicated drop devices in your infrastructure interconnected chain of paths can enhance and offload many irrelevant packet transactions from ever hitting your Firewall mitigation appliances. The thought around this approach is to remove processing cycles away from your more expensive security appliances such as firewalls or IPS, allowing said devices to dedicate their efforts toward more complicated session and/or application driven attacks.
**This article is old, see new Blocklist2ACL 2.0 project.**
Hi folks! A little script I wrote with VBscript that pulls in IP blocklists from different third party URLs and converts them in to well-formatted Cisco ASA access-lists. The idea stemed from the old days of running PeerGuardian and Moblock to inhibit known malicious or unwanted IP address from attempting to connect and stopping them right then and there on your computer’s firewall. It is similar to URL Blocklists that focus on URLs and Domain Names, but instead filering is done by IPs only. I wanted to take this IP Blocklist concept that has primarly been done at the Desktop Fireweall layer and abstract it to the Network Firewall. In this case a Cisco ASA that way all traffic that any connection that crosses the Firewall will be filtered by this list.
The script is fairly straightforward and the source code is below so you may look through it. Feel free to improve upon it and share it with others. I have a few years of writing vbscripts, but am in no way a professional coder. Also, if you by any chance know Linux Shell or Qt and could potentially port this to Linux or even better JAVA for platform independence, let me know!! That would be sweet.
Most firewalls in the consumer world are ones that are either bought at Bestbuy or supplied by your ISP as an all-in-one type of network device. These devices, such as the Linksys WRT54GL, are good enough for most user’s home setups. Providing Wireless and Wired network access with built in Firewall security. Blocking most inbound network threats , and other unwanted requests that are not pre-established (i.e. return path from an outbound request). Some of these consumer routers can be even further enhance with a rich set of plugins and network tools by using custom firmwares. DD-WRT, Tomato, or openWRT are all interdependent communities, who develop custom firmware to be used with these consumer all-in-one routers. You can check your devices compatibility with their firmware at each of their websites.
I for one own a Linksys WRT54GL router and have used both DD-WRT and Tomato. Both of these custom firmwares as well as the stock firware(Linksys) provide enough security, accessibly, and capacity for a typical consumer. However, that’s not what this article is about! This article is how to setup your own Network Firewall using a standalone Linux box! Woot!.
Why build a standalone Network Firewall?