Denial of service

Rule of thumb: ‘If you can print, you can prevent others from printing’

Any network resource can be slowed down or even made completely unavailable to legitimate users by consuming its resources in terms of CPU/memory or bandwidth. Common techniques involve stressing services (for example, web servers and applications) or protocols on the network level (for example, SYN flooding or more advanced Slowloris attacks). While those generic attacks work against network printers too, this wiki focuses on printer-specific denial of service attacks and gives a brief overview of methods to cause loss of availability and show that this can be accomplished by very simple means.

While the business impact of unavailable printers might be limited in most offices, time-critical industries like overnight digital printing companies may suffer financial loss even for short-term outages.

Currently, the following denial of service techniques are discussed in this wiki:

• Transmission channel – Blocking others by keeping a connection to port 9100/tcp open
• Document processing – Using PostScript and PJL to break printing functionality
• Physical damage – Exhausting the NVRAM's limited number of write cycles