Junos supports a variety of routing protocols. With the introduction of the SRX and J-series (past version 9.3) platforms, it also supports "flow mode", which includes stateful firewalling, NAT, and IPSec. Its a flexible routing policy language that is used for controlling route advertisements and path selection.
Junos operating system is primarily based on FreeBSD. Because FreeBSD offers a Unix-like environment, customers can access a Unix shell and execute normal Unix commands. Junos runs on most or all Juniper hardware systems. After Juniper acquired NetScreen, it integrated ScreenOS security functions into its own Junos network operating system.
The Junos CLI is a text-based command interface for configuring, troubleshooting, and monitoring the Juniper device and network traffic associated with it. It supports two types of command modes.
The functions of Operational Mode include control of the CLI environment, monitoring of hardware status, and display of information about network data that passes though or into the hardware. The Configuration mode is used for configuring the Juniper router, switch, or security device, by adding, deleting, or modifying statements in the configuration hierarchy.
Through the Juniper Developer Network (JDN) Juniper Networks provides the Junos SDK to its customers and 3rd-party developers who want to develop applications for Junos-powered devices such as Juniper Networks routers, switches, and service gateway systems. It provides a set of tools and application programming interfaces (APIs), including interfaces to Junos routing, firewall filter, UI and traffic services functions. Juniper Networks also employs the Junos SDK internally to develop parts of Junos and many Junos applications such as OpenFlow for Junos, and other traffic services.
This section is outdated. Please update this article to reflect recent events or newly available information.(October 2015)
Juniper as of June 13, 2008 had 5 percent of the $4.2 billion enterprise-router market, 18 percent of the $4.7 billion service-provider edge-router market and 30 percent of the $2.7 billion service-provider core-router market, according to the Dell'Oro Group.
^ abiXsystems. "Juniper’s JUNOS FreeBSD based router operating system". FreeBSDNews.com. Retrieved 2008-11-12. The first version of Junos was available on 7 July 1998 and since then Juniper has been updating it with new features every quarter. The release of JUNOS 9.1 in May this year was the 38th consecutive release.