Update.

(This used to be commit ac83deb73049f055f0ef159a5f3e5ec29a28efda)

1 files changed, 168 insertions, 95 deletions

diff --git a/docs/Samba3-HOWTO/TOSHARG-Securing.xml b/docs/Samba3-HOWTO/TOSHARG-Securing.xml
index a35c48e807..00ac4591fc 100644
--- a/docs/Samba3-HOWTO/TOSHARG-Securing.xml
+++ b/docs/Samba3-HOWTO/TOSHARG-Securing.xml
@@ -12,10 +12,23 @@
 
 <sect1>
 <title>Introduction</title>
+
 <para>
-This note was attached to the Samba 2.2.8 release notes because it contains an
-important security fix. The information contained here applies to Samba
-installations in general.
+<indexterm><primary>security</primary></indexterm>
+<indexterm><primary>direct internet access</primary></indexterm>
+<indexterm><primary>firewall</primary></indexterm>
+<indexterm><primary>private network</primary></indexterm>
+<indexterm><primary>barriers</primary></indexterm>
+<indexterm><primary>deterents</primary></indexterm>
+<indexterm><primary>secured networks</primary></indexterm>
+The information contained in this chapter applies in general to all Samba installations. Security us
+everyone's concern in the information technology world. A surprising number of Samba servers are being
+installed on machines that have direct internet access, thus security is made more critical than had the
+server been located behind a firewall and on a private network. Paranoia regarding server security is causing
+some  network administrators to insist on the installation of robust firewalls even on server that are located
+inside secured networks. This chapter provides brief information to assist the administrator who understands
+how to create the needed barriers and deterents against <quote>the enemy</quote>, no matter where [s]he may
+come from.
 </para>
 
 <blockquote>
@@ -38,6 +51,10 @@ of knowledge with which we may unlock the secrets of the masters.
 <title>Features and Benefits</title>
 
 <para>
+<indexterm><primary>moderately secure</primary></indexterm>
+<indexterm><primary>perimeter firewall</primary></indexterm>
+<indexterm><primary>host security</primary></indexterm>
+<indexterm><primary>Samba security</primary></indexterm>
 There are three levels at which security principles must be observed in order to render a site
 at least moderately secure. They are the perimeter firewall, the configuration of the host
 server that is running Samba, and Samba itself.
@@ -49,16 +66,21 @@ the latest protocols to permit more secure MS Windows file and print operations.
 </para>
 
 <para>
-Samba may be secured from connections that originate from outside the local network. This may be
-done using <emphasis>host-based protection</emphasis>, using Samba's implementation of a technology
-known as <quote>tcpwrappers,</quote> or it may be done be using <emphasis>interface-based exclusion</emphasis>
-so &smbd; will bind only to specifically permitted interfaces. It is also
-possible to set specific share or resource-based exclusions, for example, on the <smbconfsection name="[IPC$]"/>
-autoshare. The <smbconfsection name="[IPC$]"/> share is used for browsing purposes as well as to establish
-TCP/IP connections.
+<indexterm><primary>host-based protection</primary></indexterm>
+<indexterm><primary>interface-based exclusion</primary></indexterm>
+<indexterm><primary>resource-based exclusion</primary></indexterm>
+Samba can be secured from connections that originate from outside the local network. This can be done using
+<emphasis>host-based protection</emphasis>, using Samba's implementation of a technology known as
+<quote>tcpwrappers,</quote> or it may be done be using <emphasis>interface-based exclusion</emphasis> so
+&smbd; will bind only to specifically permitted interfaces. It is also possible to set specific share or
+resource-based exclusions, for example, on the <smbconfsection name="[IPC$]"/> autoshare. The <smbconfsection
+name="[IPC$]"/> share is used for browsing purposes as well as to establish TCP/IP connections.
 </para>
 
 <para>
+<indexterm><primary>Access Control Entries</primary><see>ACE</see></indexterm>
+<indexterm><primary>ACL</primary></indexterm>
+<indexterm>controls<primary></primary></indexterm>
 Another method by which Samba may be secured is by setting Access Control Entries (ACEs) in an Access 
 Control List (ACL) on the shares themselves. This is discussed in
 <link linkend="AccessControls">File, Directory, and Share Access Controls</link>.
@@ -81,6 +103,9 @@ before someone will find yet another vulnerability.
 	<title>Using Host-Based Protection</title>
 
 	<para>
+<indexterm><primary>outside threat</primary></indexterm>
+<indexterm><primary>insecure</primary></indexterm>
+<indexterm><primary>Internet</primary></indexterm>
 	In many installations of Samba, the greatest threat comes from outside
 	your immediate network. By default, Samba accepts connections from
 	any host, which means that if you run an insecure version of Samba on
@@ -89,21 +114,25 @@ before someone will find yet another vulnerability.
 	</para>
 
 	<para>
+<indexterm><primary>allow access</primary></indexterm>
+<indexterm><primary>range of hosts</primary></indexterm>
 	One of the simplest fixes in this case is to use the <smbconfoption name="hosts allow"/> and
 	<smbconfoption name="hosts deny"/> options in the Samba &smb.conf; configuration file to
 	allow access to your server only from a specific range of hosts. An example might be:
+	<smbconfblock>
+	<smbconfoption name="hosts allow">127.0.0.1 192.168.2.0/24 192.168.3.0/24</smbconfoption>
+	<smbconfoption name="hosts deny">0.0.0.0/0</smbconfoption>
+	</smbconfblock>
 	</para>
 
-	<para><smbconfblock>
-<smbconfoption name="hosts allow">127.0.0.1 192.168.2.0/24 192.168.3.0/24</smbconfoption>
-<smbconfoption name="hosts deny">0.0.0.0/0</smbconfoption>
-	</smbconfblock></para>
-
 	<para>
+<indexterm><primary>localhost</primary></indexterm>
+<indexterm><primary>private networks</primary></indexterm>
+<indexterm><primary>called name</primary></indexterm>
 	The above will allow SMB connections only from <constant>localhost</constant> (your own
 	computer) and from the two private networks 192.168.2 and 192.168.3. All other
 	connections will be refused as soon as the client sends its first packet. The refusal
-	will be marked as <errorname>not listening on called name</errorname> error.
+	will be marked as <literal>not listening on called name</literal> error.
 	</para>
 
 	</sect2>
@@ -114,13 +143,13 @@ before someone will find yet another vulnerability.
 	<para>
 	If you want to restrict access to your server to valid users only, then the following
 	method may be of use. In the &smb.conf; <smbconfsection name="[global]"/> section put:
+	<smbconfblock>
+	<smbconfoption name="valid users">@smbusers, jacko</smbconfoption>
+	</smbconfblock>
 	</para>
 
-	<para><smbconfblock>
-<smbconfoption name="valid users">@smbusers, jacko</smbconfoption>
-	</smbconfblock></para>
-
 	<para>
+<indexterm><primary>smbusers</primary></indexterm>
 	This restricts all server access either to the user <emphasis>jacko</emphasis>
 	or to members of the system group <emphasis>smbusers</emphasis>.
 	</para>
@@ -132,6 +161,9 @@ before someone will find yet another vulnerability.
 	<title>Using Interface Protection</title>
 
 	<para>
+<indexterm><primary>network interface</primary></indexterm>
+<indexterm><primary>accept connections</primary></indexterm>
+<indexterm><primary>Internet</primary></indexterm>
 	By default, Samba accepts connections on any network interface that
 	it finds on your system. That means if you have an ISDN line or a PPP
 	connection to the Internet then Samba will accept connections on those
@@ -140,27 +172,46 @@ before someone will find yet another vulnerability.
 
 	<para>
 	You can change this behavior using options like this:
+	<smbconfblock>
+	<smbconfoption name="interfaces">eth* lo</smbconfoption>
+	<smbconfoption name="bind interfaces only">yes</smbconfoption>
+	</smbconfblock>
 	</para>
 
-	<para><smbconfblock>
-<smbconfoption name="interfaces">eth* lo</smbconfoption>
-<smbconfoption name="bind interfaces only">yes</smbconfoption>
-	</smbconfblock></para>
+	<para>
+<indexterm><primary>interfaces</primary></indexterm>
+<indexterm><primary>loopback interface</primary></indexterm>
+<indexterm><primary>Ethernet adapters</primary></indexterm>
+<indexterm><primary>listen for connections</primary></indexterm>
+	This tells Samba to listen for connections only on interfaces with a name starting with
+	<constant>eth</constant> such as <constant>eth0 or eth1</constant>, plus on the loopback interface called
+	<constant>lo</constant>. The name you will need to use depends on what OS you are using. In the above, I used
+	the common name for Ethernet adapters on Linux.
+	</para>
 
 	<para>
-	This tells Samba to only listen for connections on interfaces with a
-	name starting with <constant>eth</constant> such as <constant>eth0 or eth1</constant>, plus on the loopback
-	interface called <constant>lo</constant>. The name you will need to use depends on what
-	OS you are using. In the above, I used the common name for Ethernet
-	adapters on Linux.
+<indexterm><primary>PPP</primary></indexterm>
+<indexterm><primary>SMB</primary></indexterm>
+<indexterm><primary>cracker</primary></indexterm>
+<indexterm><primary>confirm address</primary></indexterm>
+	If you use the above and someone tries to make an SMB connection to your host over a PPP interface called
+	<constant>ppp0,</constant> then [s]he will get a TCP connection refused reply. In that case, no Samba code
+	is run at all, because the operating system has been told not to pass connections from that interface to any
+	Samba process. However, the refusal helps a would-be cracker by confirming that the IP address provides
+	valid active services.
 	</para>
 
 	<para>
-	If you use the above and someone tries to make an SMB connection to
-	your host over a PPP interface called <constant>ppp0,</constant> then he or she will get a TCP
-	connection refused reply. In that case, no Samba code is run at all because
-	the operating system has been told not to pass connections from that
-	interface to any Samba process.
+<indexterm><primary>ignore connection</primary></indexterm>
+<indexterm><primary>refusing connection</primary></indexterm>
+<indexterm><primary>exploitation</primary></indexterm>
+<indexterm><primary>denial of service</primary></indexterm>
+<indexterm><primary>firewall</primary></indexterm>
+	A better response would be to ignore the connection (from, e.g., ppp0) altogether. The
+	advantage of ignoring the connection attempt, as compared with refusing it, is that it foils those who
+	probe an interface with the sole intention of finding valid IP addresses for later use in exploitation
+	or denial of service attacks. This method of dealing with potential malicious activity demands the
+	use of appropriate firewall mechanisms.
 	</para>
 
 	</sect2>
@@ -169,36 +220,45 @@ before someone will find yet another vulnerability.
 	<title>Using a Firewall</title>
 
 	<para>
-	Many people use a firewall to deny access to services they do not
-	want exposed outside their network. This can be a good idea,
-	although I recommend using it in conjunction with the above
-	methods so you are protected even if your firewall is not active
-	for some reason.
+<indexterm><primary>deny access</primary></indexterm>
+<indexterm><primary>exposed</primary></indexterm>
+<indexterm><primary>firewall active</primary></indexterm>
+	Many people use a firewall to deny access to services they do not want exposed outside their network. This can
+	be a good idea, although I recommend using it in conjunction with the above methods so you are protected even
+	if your firewall is not active for some reason.
 	</para>
 
 	<para>
-	If you are setting up a firewall, you need to know what TCP and
-	UDP ports to allow and block. Samba uses the following:
+	If you are setting up a firewall, you need to know what TCP and UDP ports to allow and block. Samba uses
+	the following:
+<indexterm><primary>Port 135/TCP</primary></indexterm>
+<indexterm><primary>Port 137/UDP</primary></indexterm>
+<indexterm><primary>Port 138/UDP</primary></indexterm>
+<indexterm><primary>Port 139/TCP</primary></indexterm>
+<indexterm><primary>Port 445/TCP</primary></indexterm>
 	</para>
 
 	<simplelist>
-		<member>UDP/137 - used by nmbd</member>
-		<member>UDP/138 - used by nmbd</member>
-		<member>TCP/139 - used by smbd</member>
-		<member>TCP/445 - used by smbd</member>
+		<member>Port 135/TCP - used by smbd</member>
+		<member>Port 137/UDP - used by nmbd</member>
+		<member>Port 138/UDP - used by nmbd</member>
+		<member>Port 139/TCP - used by smbd</member>
+		<member>Port 445/TCP - used by smbd</member>
 	</simplelist>
 
 	<para>
-	The last one is important because many older firewall setups may not be
-	aware of it, given that this port was only added to the protocol in
-	recent years. 
+<indexterm><primary>firewall setups</primary></indexterm>
+	The last one is important because many older firewall setups may not be aware of it, given that this port
+	was only added to the protocol in recent years.
 	</para>
 
 	<para>
-	When configuring a firewall, the high order ports (1024-65535) are often
-	used for outgoing connections and therefore should be permitted through the
-	firewall. It is prudent to block incoming packets on the high order ports
-	except for established connections.
+<indexterm><primary>configuring a firewall</primary></indexterm>
+<indexterm><primary>high order ports</primary></indexterm>
+<indexterm><primary>block incoming packets</primary></indexterm>
+	When configuring a firewall, the high order ports (1024-65535) are often used for outgoing connections and
+	therefore should be permitted through the firewall. It is prudent to block incoming packets on the high order
+	ports except for established connections.
 	</para>
 
 	</sect2>
@@ -207,37 +267,41 @@ before someone will find yet another vulnerability.
 	<title>Using IPC$ Share-Based Denials </title>
 
 	<para>
-	If the above methods are not suitable, then you could also place a
-	more specific deny on the IPC$ share that is used in the recently
-	discovered security hole. This allows you to offer access to other
-	shares while denying access to IPC$ from potentially untrustworthy
-	hosts.
+<indexterm><primary>IPC$</primary></indexterm>
+<indexterm><primary>deny</primary></indexterm>
+<indexterm><primary>security hole</primary></indexterm>
+	If the above methods are not suitable, then you could also place a more specific deny on the IPC$ share that
+	is used in the recently discovered security hole. This allows you to offer access to other shares while
+	denying access to IPC$ from potentially untrustworthy hosts.
 	</para>
 
 	<para>
 	To do this you could use:
+	<smbconfblock>
+	<smbconfsection name="[IPC$]"/>
+	<smbconfoption name="hosts allow">192.168.115.0/24 127.0.0.1</smbconfoption>
+	<smbconfoption name="hosts deny">0.0.0.0/0</smbconfoption>
+	</smbconfblock>
 	</para>
 
-	<para><smbconfblock>
-<smbconfsection name="[IPC$]"/>
-<smbconfoption name="hosts allow">192.168.115.0/24 127.0.0.1</smbconfoption>
-<smbconfoption name="hosts deny">0.0.0.0/0</smbconfoption>
-	</smbconfblock></para>
-
 	<para>
-	This instructs Samba that IPC$ connections are not allowed from
-	anywhere except the two listed network addresses (localhost and the 192.168.115
-	subnet). Connections to other shares are still allowed. Because the
-	IPC$ share is the only share that is always accessible anonymously,
-	this provides some level of protection against attackers who do not
-	know a valid username/password for your host.
+<indexterm><primary>IPC$</primary></indexterm>
+<indexterm><primary>protection against attackers</primary></indexterm>
+<indexterm><primary>valid username/password</primary></indexterm>
+	This instructs Samba that IPC$ connections are not allowed from anywhere except the two listed network
+	addresses (localhost and the 192.168.115 subnet). Connections to other shares are still allowed. Because the
+	IPC$ share is the only share that is always accessible anonymously, this provides some level of protection
+	against attackers who do not know a valid username/password for your host.
 	</para>
 
 	<para>
-	If you use this method, then clients will be given an <errorname>`access denied'</errorname>
-	reply when they try to access the IPC$ share. Those clients will not be able to
-	browse shares and may also be unable to access some other resources.  This is not
-	recommended unless for some reason you cannot use one of the other methods just discussed.
+<indexterm><primary>access denied</primary></indexterm>
+<indexterm><primary>IPC$</primary></indexterm>
+<indexterm><primary>browse shares</primary></indexterm>
+	If you use this method, then clients will be given an <literal>`access denied'</literal> reply when they try
+	to access the IPC$ share. Those clients will not be able to browse shares and may also be unable to access
+	some other resources.  This is not recommended unless for some reason you cannot use one of the other methods
+	just discussed.
 	</para>
 
 	</sect2>
@@ -246,6 +310,7 @@ before someone will find yet another vulnerability.
 	<title>NTLMv2 Security</title>
 
 	<para>
+<indexterm><primary>NTLMv2</primary></indexterm>
 	To configure NTLMv2 authentication, the following registry keys are worth knowing about:
 	</para>
 
@@ -281,10 +346,13 @@ before someone will find yet another vulnerability.
 <title>Upgrading Samba</title>
 
 <para>
-Please check regularly on <ulink noescape="1" url="http://www.samba.org/">http://www.samba.org/</ulink> for updates and
-important announcements. Occasionally security releases are made, and 
-it is highly recommended to upgrade Samba when a security vulnerability
-is discovered. Check with your OS vendor for OS-specific upgrades.
+<indexterm><primary>updates</primary></indexterm>
+<indexterm><primary>important announcements</primary></indexterm>
+<indexterm><primary>security vulnerability</primary></indexterm>
+Please check regularly on <ulink noescape="1" url="http://www.samba.org/">http://www.samba.org/</ulink> for
+updates and important announcements. Occasionally security releases are made, and it is highly recommended to
+upgrade Samba promptly when a security vulnerability is discovered. Check with your OS vendor for OS-specific
+upgrades.
 </para>
 
 </sect1>
@@ -293,17 +361,17 @@ is discovered. Check with your OS vendor for OS-specific upgrades.
 <title>Common Errors</title>
 
 <para>
-If all of Samba and host platform configurations were really as intuitive as one might like them to be, this
-section would not be necessary. Security issues are often vexing for a support person to resolve, not
-because of the complexity of the problem, but because most administrators who post what turns
-out to be a security problem request are totally convinced that the problem is with Samba.
+If all Samba and host platform configurations were really as intuitive as one might like them to be, this
+chapter would not be necessary. Security issues are often vexing for a support person to resolve, not because
+of the complexity of the problem, but because most administrators who post what turns out to be a security
+problem request are totally convinced that the problem is with Samba.
 </para>
 
 	<sect2>
 	<title>Smbclient Works on Localhost, but the Network Is Dead</title>
 
 	<para>
-	This is a common problem. Red Hat Linux (and others) installs a default firewall.
+	This is a common problem. Linux vendors tend to install a default firewall.
 	With the default firewall in place, only traffic on the loopback adapter (IP address 127.0.0.1)
 	is allowed through the firewall.
 	</para>
@@ -317,36 +385,41 @@ out to be a security problem request are totally convinced that the problem is w
 	</sect2>
 
 	<sect2>
-	<title>Why Can Users Access Home Directories of Other Users?</title>
+	<title>Why Can Users Access Other Users Home Directories?</title>
 
 	<para>
 	<quote>
-	We are unable to keep individual users from mapping to any other user's
-	home directory once they have supplied a valid password! They only need
-	to enter their own password. I have not found any method to configure
-	Samba so that  users may map only their own home directory.
+<indexterm><primary>mapping home directory</primary></indexterm>
+<indexterm><primary>own home directory</primary></indexterm>
+	We are unable to keep individual users from mapping to any other user's home directory once they have
+	supplied a valid password! They only need to enter their own password. I have not found any method to
+	configure Samba so that  users may map only their own home directory.
 	</quote>
 	</para>
 
 	<para><quote>
-	User xyzzy can map his home directory. Once mapped, user xyzzy can also map
-	anyone else's home directory.
+	User xyzzy can map his home directory. Once mapped, user xyzzy can also map anyone else's home directory.
 	</quote></para>
 
 	<para>
-	This is not a security flaw, it is by design. Samba allows users to have
-	exactly the same access to the UNIX file system as when they were logged
-	onto the UNIX box, except that it only allows such views onto the file 
+<indexterm><primary>security flaw</primary></indexterm>
+<indexterm><primary>defined shares</primary></indexterm>
+	This is not a security flaw, it is by design. Samba allows users to have exactly the same access to the UNIX
+	file system as when they were logged onto the UNIX box, except that it only allows such views onto the file
 	system as are allowed by the defined shares.
 	</para>
 
 	<para>
+<indexterm><primary>UNIX home directories</primary></indexterm>
+<indexterm><primary>permissions</primary></indexterm>
 	If your UNIX home directories are set up so that one user can happily <command>cd</command>
 	into another user's directory and execute <command>ls</command>, the UNIX security solution is to change file
 	permissions on the user's home directories so that the <command>cd</command> and <command>ls</command> are denied.
 	</para>
 
 	<para>
+<indexterm><primary>security policies</primary></indexterm>
+<indexterm><primary>permissions</primary></indexterm>
 	Samba tries very hard not to second guess the UNIX administrator's security policies and
 	trusts the UNIX admin to set the policies and permissions he or she desires.
 	</para>
@@ -360,11 +433,11 @@ out to be a security problem request are totally convinced that the problem is w
 	The <smbconfoption name="only user"></smbconfoption> works in conjunction with the <smbconfoption name="users">list</smbconfoption>,
 	so to get the behavior you require, add the line:
 	<smbconfblock>
-<smbconfoption name="users">%S</smbconfoption>
-</smbconfblock>
+	<smbconfoption name="users">%S</smbconfoption>
+	</smbconfblock>
 	This is equivalent to adding
 	<smbconfblock>
-<smbconfoption name="valid users">%S</smbconfoption>
+	<smbconfoption name="valid users">%S</smbconfoption>
 	</smbconfblock>
 	to the definition of the <smbconfsection name="[homes]"/> share, as recommended in
 	the &smb.conf; man page.