(Secret Internet Protocol Router Network) is a system of interconnected computer networks
used by the U.S. Department of Defense
and the U.S. Department of State
to transmit classified information
(up to and including information classified SECRET
) by packet switching
over the TCP/IP protocols
in a "completely secure" environment. It also provides services such as hypertext
documents and electronic mail
. In other words, the SIPRNet is the DoD’s classified version of the civilian Internet
together with its counterpart, the TOP SECRET
Joint Worldwide Intelligence Communications System, JWICS
. The NIPRNET
is used to exchange sensitive but unclassified (SBU) information.
Naming and history
SIPRNet and NIPRnet are referred to colloquially as SIPR (pronounced 'sipper') and NIPR (pronounced 'nipper'), respectively. SIPRNet supersedes the earlier DSNET 1, the SECRET level of the Defense Data Network
based on ARPANET
Comparisons to Internet
Except for existing within a secure environment, the SIPRNet is virtually indistinguishable from the Internet
to the user. Its chief visible difference is the domain name system, with almost all sites being under '.smil.mil'
. Among its many features, computers cleared for SIPRNet access connect to the network via secure dial-up
connections, access web pages
written in standard HTML
using a standard web browser
, can upload and download files via FTP
connections, and can send or receive email messages through SMTP
services using any standard email client
. All data transmitted on SIPRNet between secure facilities must be encrypted by approved NSA encryption systems
. While the public Internet can be used to transmit encrypted SIPRNet packets ("SIPR over NIPR"), no access is permitted between the two networks.
The network supports a variety of Defense Department networks and systems, such as:
and many other classified military applications.
SIPRNet hosts a forum called CAVNET which is used in Iraq to share Tactics, Techniques, and Procedures data.