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Device Profile: Opengear CM4000 remote console servers

Feb 14, 2005 — by LinuxDevices Staff — from the LinuxDevices Archive — 56 views

Opengear's CM4000 remote console servers come in 8-, 16-, and 48-port models, and are powered by an ARM-based system-on-chip processor running an embedded uClinux kernel along with software from the Open KVM (okvm) and other open source projects.

CM4000 family portrait

According to CEO Bob Waldie, Opengear plans to offer standard and customized devices that enable secure, non-intrusive remote access and control of “human interface devices” — providing remote KVM (keyboard/video/mouse) functions and power recycling, for example. Other applications will include remote monitoring and control of routers, gateways, PBXs, and other devices.

According to Waldie, the CM4008 (photo), CM4116 (photo), and CM4148 (shown below) enable administrators to securely monitor and manage hundreds of serial consoles remotely, via the Internet.

Opengear's CM4148 provides 48 serial ports
(Click image for larger view)

The devices can be accessed either “in band,” via LAN- or WAN-based TCP/IP, or “out-of-band,” via a direct connection over a dial-up modem port. Both connections provide secure, encrypted access to the remote resources using up to 128-bit AES encryption, Opengear says. The devices also include a variety of filtering and access logging functions, including the ability to archive console logs off-line. For added security, administrators can restrict device access by IP address, password, or account.

CEO Bob Waldie claims that Opengear's new console servers “deliver the highest quality console server solutions affordably priced for the smaller office.” The CM4000 offerings are priced at $30 to $40 per port, in contrast to “unaffordable [competitive offerings] at $100-$200 per port,” Waldie said.

Another unique feature of Opengear's console server products is the ability to customize their embedded software. The units incorporate software from the Opengear-supported okvm open source console and KVM management software project, and they ship with full source code, Waldie says.

In developing its console server family, “the main goal was to achieve a design with the lowest price that delivered premium performance using a relatively small memory footprint,” according to Waldie. “This required a highly integrated CPU with embedded network ports, memory, and general purpose I/O interfaces, [and] which was well supported by uCLinux.” It was particularly important that the serial port controllers to be well supported by uCLinux, Waldie adds.

The CM4000 console servers include a simple Web browser that allows easy configuration of the device including its access security and console interface ports. The devices can also be configured directly from the command line of the embedded Linux kernel.


The CM4000 console servers are based on a 166MHz Micrel KS8695P (“Centaur”) system-on-chip processor, which integrates a 166MHz ARM9TM core along with a memory management unit (MMU), 5-port managed Ethernet switch (1 for WAN, 4 for LAN switching), and 33MHz PCI bridge (see block diagram). For memory resources, the 8-port CM4008 includes 16MB SDRAM and 8MB Flash memory, while the 16-port CM4116 and 48-port CM4148 come with 64MB SDRAM and 16MB Flash.

The CM4008's uClinux-based embedded computer
(Click image for larger view)

All of the devices' RJ-45 RS-232 serial ports support 2400 to 230,400 bps data rates. In addition, each server also includes one DB-9 RS-232 serial port (supporting 2400 to 115,200 bps) for out-of-band local or modem connection, as well as an RJ-11 10/100Base-T Ethernet port for LAN or WAN connection.

The serial ports are implemented by means of one or more EXAR 17D158 PCI octal UARTs, which are backward-compatible with PC-standard 16550 COM ports, but provide 64-byte TX and RX FIFOs and automatic RTS/CTS or DTR/DSR Hardware Flow Control, according to Waldie. Each port can communicate at up to 230Kbps, and when operating at 166MHz, the CPU can easily transfer data on 48 serial ports at 115.2Kbps, Waldie says. The EXAR 17D158 is supported by uCLinux, he adds.

Although the KS8695P CPU includes five 10/100 Ethernet transceivers and five MACs, the CM4000 family only uses one of the interfaces, for a fast Ethernet connection to the network (LAN or WAN). The chip is capable of routing IP traffic at over 40 Mbps when running uCLinux, according to Waldie.


The CM4000 console servers are powered by uClinux, an embedded Linux implementation initially developed to support microcontroller-like processors that lacked memory management units (MMUs).

In addition to uClinux, other open source software used in Opengear's CM4000 console servers includes uClibc, busybox, fnord http server, bash, STLport, OpenSSH, OpenNTPD (network time protocol server), and a “smattering of minor opensource libraries and utilities,” according to Waldie.

Busybox is used for most command line utilities, Waldie says. OpenSSH is used for secure access to the serial ports: “When users ssh to a TCP port of 3000+serial-port-number, they are connected to that serial port via the portmanager. We use XML to store all our config, and Expat and libscew to do the parsing and generation of the config,” he added.

“The system includes a Web-based UI (user interface), built as a CGI written in C++ using the VBMcgi library. In addition, scp client and servers are included in the device, enabling administrators to save, restore, and/or generate a custom XML configuration and distribute it to multiple console servers,” continued Waldie.

“The imaginatively named portmanager handles I/O with all the serial ports, and provides a history buffer, and proxies simultaneous access from multiple clients to the same serial port. pcre is used to do pattern based alerts and logging, so matches can be more complex than simple keywords, and can use Perl regular expressions. The system also uses PAM with pam_radius and pam_tacplus to authenticate against Radius or TACACS+ servers,” Waldie said.

The out-of-band console port supports automatic detection of PPP, enabling it to be used as both a text-only login when the network is down, or to accessed via a modem for emergency network access.

Currently, the CM4000 devices are running a 2.4.x uClinux kernel, based mainly on the standard uClinux distribution, according to Waldie. “Any changes we have needed to make to the Linux kernel to support hardware, etc. are being folded back into the mainline uClinux release,” he said. “Some of the modifications we made to libraries or programs from the uClinux-dist tree have been pretty specific to the okvm situation, so at this stage it probably isn't useful to roll them back into the mainstream uClinux-dist. Irrespective, all changes we make are available via our source releases, even if they aren't pushed back to the mainstream uClinux sources.”

Regarding the benefit of using uClinux in the design of the console servers, Waldie adds: “Opengear only formed and got some engineers onboard mid last year, and we'll be shipping volume product this quarter . . . and we were able to do this by leveraging the extremely flexible uClinux distribution. The uClinux distribution already provided a large number of 'ready for embedded use' applications to setup a base system. This allowed us to focus on just the software that is Opengear product specific. The distribution allowed us to have a full operating system running on the new hardware as soon as the hardware was operational. The freely available uClinux distribution and associated tools as feature rich, flexible and easy to use, starting from scratch just doesn't make sense.”

No stranger to uClinux

Opengear founder Bob Waldie is no stranger to Linux-based gadgets and open-source software. Waldie formerly founded Moreton Bay, a hardware-oriented embedded company based in Brisbane, Australia, that specialized in uClinux-based security solutions. In the spring of 2000, Moreton Bay was acquired by Lineo, where Waldie served as COO. The company was subsequently spun back out as Snapgear — a company that has played a major role in maintaining uClinux and offering free uClinux distribution — in the fall of 2001. Snapgear, in turn, was acquired by Cyberguard in May 2004.

Opengear's executive team also includes President Tony Merenda, former CTO of Stallion Technologies, the remote connectivity hardware company that Waldie founded prior to founding Moreton Bay.

Opengear cites an IDC study that projected worldwide revenues of $925 million for the 2005 KVM market, up from $725 million in 2004. Other vendors marketing Linux-powered KVM equipment include Avocent, Cyclades, and Digi International, according to Opengear.


Opengear's Linux-powered CM4000 console servers are priced at $495, $795, and $1495, for the 8-port CM4008, 16-port CM4116, and 48-port CM4148, respectively. The devices will be showcased in Opengear's booth at LinuxWorld this week. Opengear says it will also preview KVM-over-IP products that are slated to be released later this year.

Waldie says that Opengear's products are manufactured in China, and that the company anticipates that a large portion of its business will be based on building customized versions of its products for OEMs.

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