saned - SANE network daemon

saned [-d|-s [n]]

saned is the SANE (Scanner Access Now Easy) daemon that allows remote clients to access image acquisition devices available on the local host.

The -d and -s flags request that saned run in debug mode (as opposed to inetd(8) mode). In this mode, saned explicitly waits for a connection request. When compiled with debugging enabled, these flags may be followed by a number to request debug info. The larger the number, the more verbose the debug output. E.g., -d128 will request printing of all debug info. Debug level 0 means no debug output at all. The default value is 2. If flag -d is used, the debug messages will be printed to stderr while -s requests using syslog.

If saned is run from inetd or xinetd, no option can be given.

First and foremost: saned is not intended to be exposed to the internet or other non-trusted networks. Make sure that access is limited by tcpwrappers and/or a firewall setup. Don't depend only on saned's own authentification. Don't run saned as root if it's not necessary. And do not install saned as setuid root.

The contents of the saned.conf file is a list of host names, IP addresses or IP subnets (CIDR notation) that are permitted to use local SANE devices. IPv6 addresses must be enclosed in brackets, and should always be specified in their compressed form. Connections from localhost are always permitted. Empty lines and lines starting with a hash mark (#) are ignored. A line containing the single character ``+'' is interpreted to match any hostname. This allows any remote machine to use your scanner and may present a security risk, so this shouldn't be used unless you know what you're doing. A sample configuration file is shown below:

scan-client.somedomain.firm

# this is a comment

192.168.0.1

192.168.2.12/29

[::1]

[2001:7a8:185e::42:12]/64

The case of the host names does not matter, so AHost.COM is considered identical to ahost.com.

For saned to work properly, it is also necessary to add a configuration line to /etc/inetd.conf. Note that your inetd must support IPv6 if you want to connect to saned over IPv6 ; xinetd and openbsd-inetd are known to support IPv6, check the documentation for your inetd daemon.

The configuration line normally looks like this:

sane-port stream tcp nowait saned.saned /usr/sbin/saned saned

However, if your system uses tcpd(8) for additional security screening, you may want to disable saned access control by putting ``+'' in saned.conf and use a line of the following form in /etc/inetd.conf instead:

sane-port stream tcp nowait saned.saned /usr/sbin/tcpd /usr/sbin/saned

Note that both examples assume that there is a saned group and a saned user. If you follow this example, please make sure that the access permissions on the special device are set such that saned can access the scanner (the program generally needs read and write access to scanner devices).

If xinetd is installed on your system instead of inetd the following example for xinetd.conf may be helpful:

# default: off
# description: The sane server accepts requests 
# for network access to a local scanner via the
# network.
service sane-port
{
   port        = 6566
   socket_type = stream
   wait        = no
   user        = saned
   group       = saned
   server      = /usr/sbin/saned
}

Finally, it is also necessary to add a line of the following form to /etc/services:

sane-port 6566/tcp # SANE network scanner daemon

The official IANA short name for port 6566 is "sane-port". The older name "sane" is now deprecated.

In addition to the control connection (port 6566) saned also uses a data connection. The port of this socket is selected by the operating system and can't be specified by the user currently. This may be a problem if the connection must go through a firewall (packet filter). If you must use a packet filter, make sure that all ports > 1024 are open on the server for connections from the client.

/etc/hosts.equiv

The hosts listed in this file are permitted to access all local SANE devices. Caveat: this file imposes serious security risks and its use is not recommended.

/etc/sane.d/saned.conf

Contains a list of hosts permitted to access local SANE devices (see also description of SANE_CONFIG_DIR below).

/etc/sane.d/saned.users

If this file contains lines of the form

user:password:backend

access to the listed backends is restricted. A backend may be listed multiple times for different user/password combinations. The server uses MD5 encryption if supported by the client.

SANE_CONFIG_DIR

This environment variable specifies the list of directories that may contain the configuration file. Under UNIX, the directories are separated by a colon (`:'), under OS/2, they are separated by a semi-colon (`;'). If this variable is not set, the configuration file is searched in two default directories: first, the current working directory (".") and then in /etc/sane.d. If the value of the environment variable ends with the directory separator character, then the default directories are searched after the explicitly specified directories. For example, setting SANE_CONFIG_DIR to "/tmp/config:" would result in directories "tmp/config", ".", and "/etc/sane.d" being searched (in this order).

sane(7), scanimage(1), xscanimage(1), xcam(1), sane-dll(5), sane-net(5), sane-"backendname"(5)

http://www.penguin-breeder.org/?page=sane-net

David Mosberger