Saturday, June 20, 2015

Printing from Android Phones to Epson printers

The problem of printing from mobile devices is somewhat involved. The main problem is that standards like WiFi Direct or bluetooth printing are still in early stages of deployment. Some vendors have their own solutions that work pretty well with their devices, but they tend to be islands. Google has cloud print, but that requires a dedicated print server on the local network running headless Chrome to route the print jobs. I don't know the details of Apple Cloud Print, but it probably works in a similar way, with some local device acting as the print server.

On my Samsung Galaxy S6, I decided to download the Epson Print Enabler from the Play Store. Once it was installed and enabled, I took the phone to close proximity of my printer, and Epson WF-3520 multi-purpose wireless inkjet and tried to print a web page from Chrome. Chrome defaults to printing to a PDF document, but I was able to select the Epson from a drop down list, deselect the pages I did not want to print and send a single page of the web site to the printer. It worked like magic.

This is one of the island solutions that might only work with Android phones and Epson wireless printers, but it does work without any print server set up or routing through the Internet. The Epson printer is the best wireless inkjet I've owned and is highly recommended whether you want to use the Android printing features or not.

Saturday, June 6, 2015

Limiting connections to port 80

The Linux software firewall, iptables, has the ability to limit the number of concurrent connections on a specific port. This could be used as a crude DDOS defense. It won't save a web site, but it might save the server from becoming overwhelmed and unresponsive. Here is an example of limiting the number of connections on port 80 to 25. After 25 open connections, the next connection is dropped.

iptables -A INPUT -p tcp --syn --dport 80 -m connlimit --connlimit-above 25 -j REJECT --reject-with tcp-reset