System information

C Application of the CHARM
The following descriptions list the most important programs of the CHARM card. They
are divided into third parts programs which were adapted to run on the CHARM and the
CHARM specific applications.
C.1 Third Party Application
Web server The CHARM card uses two web servers: boa and axTLS [111]. Boa is a small
embedded web server without access control features. It will be replaced by axTLS
in a newer revision of the CHARM card. AxTLS supports access control features and
encrypted connections. It has a very small footprint which is therefore particularly
suitable for embedded systems. Furthermore, it is actively maintained. The web pages
and CGI scripts are stored in the directory /usr/www.
DHCP Client The default IP address of a CHARM card is 192.168.1.10. However, the
CHARM card starts a DHCP client at boot time to get dynamically its IP address.
Therefore the DHCP client udhcpc is used which is part of the BusyBox function. Ev-
ery DHCP response is forwarded to a script located in /usr/share/udhcpc/ directory.
Among other things, this script is responsible for mounting an NFS share at start-up
for additional storage space.
SSH Server The CHARM card uses the SSH server dropbear. It supports SSH1 and SSH2.
Dmidecode Prints out the DMI information of the host computer.
C.2 CHARM Specific Application
keyb_cmd This program emulates keystrokes to the host computer. There are two pos-
sibilities to sent keystrokes to the host computer: via USB or PCI. The key_cmd
can use both interfaces. In the case using the USB interface, the program sends the
keystrokes via the emulated HID keyboard. Section 5.1.3 describes the HID interface
of the CHARM card. But the key_cmd can also use the PCI interface. More infor-
mation about emulating a keyboard via the PCI interface can be obtained in section
5.2.
terminal The terminal program provides the textual content of the host screen if the host
runs an alphanumeric video mode. Furthermore, the program generates either a
screenshot or it runs in an interactive mode which provides a console based access to
the host computer.
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