Shellinabox/man

NAME

shellinaboxd - publish command line shell through AJAX interface

SYNOPSIS

DESCRIPTION

The shellinaboxd daemon implements a webserver that listens on the specified port. The web server publishes one or more services that will be displayed in a VT100 emulator implemented as an AJAX web application. By default, the port is 4200 and the default service URL is http://localhost:4200/.

If no particular service was requested, the server launches /bin/login querying the user for their username and password. It then starts the user's default login shell.

Any modern JavaScript and CSS enabled browser will be able to access the published service without requiring additional plugins.

CONFIGURATION

There are no configuration files or permanent settings for shellinaboxd.

A small number of run-time configuration options are available from a context menu that becomes available when clicking the right mouse button. These options get persisted in a browser cookie.

Many sites already have a web server running and would like to integrate shellinaboxd into their existing site. This is most commonly done by means of a reverse-proxy entry for the main web server. For Apache this would require adding an option such as: <Location /shell> ProxyPass http://localhost:4200/ Order allow,deny Allow from all </Location>

If you are using a different web server, refer to that server's documentation on how to configure reverse proxy operations.

When using a reverse proxy, the --localhost-only option would normally be enabled as well. In addition, the --disable-ssl might also be considered de‐ pending on the exact configuration details of the reverse proxy.

DIAGNOSTICS

The daemon returns a non-zero exit code in case of failure. With the exception of a small number of common error cases that are handled explicitly, most errors result in printing a "Check failed" message. This does not typically indicate a bug in the program but is instead its normal way of report‐ ing errors.

Common failure conditions are reusing a port that is already in use, lack of sufficient privileges to run a service, failure to find SSL/TLS certifi‐ cates, and failure to write newly generated certificates to the certification directory.

SECURITY

The daemon uses privilege separation techniques to allow it to drop privileges early. It is aware of setuid flags and restricts some operations when launched as a setuid application.

Despite these safety features, a bug could conceivably lead to a determined attacker gaining elevated privileges. It is therefore strongly discouraged to set the setuid flag on the binary.

The expected deployment would be from a system rc script launched by /sbin/init. For extra security, the --group and --user options should be used to change to a dedicated user.

BUGS

Due to browser limitations, some features might not be available to users of all browers.

Konqueror does not allow for reliable interception of CTRL keys. If you press a key together with the CTRL modifier, it continues performing the browser's predefined behavior for this particular key combination. In most cases, it also fails to report the correct key to the terminal emulator. As a work-around, pressing both the CTRL and the WINDOWS key sometimes works.

Some browsers, most notably IE on Windows, disallow interception of ALT keys and always interpret these keys as menu accelerators. As a work-around, many UNIX applications allow pressing ESC, instead of ALT.

When using non-US keyboard layouts, some browser do not allow for reliably determining shifted ALT keys. Please report these cases if they turn out to be a problem, as work-arounds might be possible.

Access to the native clipboard is typically not possible. Instead, an internal clipboard accessible from the right-button context menu is used for all but IE.

Some browsers restrict the number of concurrent connections to a server. This restricts how many AJAX terminals can be opened simultaneously. If this becomes a problem, users can typically reconfigure their browsers to raise the limit.

There have been reports of the VLC plugin on Linux/x86_64 crashing Firefox when the browser page gets reloaded. Setting the --no-beep option eliminates all references to VLC and thus appears to work around this crash.