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ProFTPD module mod_wrap2
ProFTPD module mod_wrap2
The mod_wrap2 package allows the proftpd daemon to
provide tcpwrapper-like access control rules while running
in standalone mode. It also allows for those access rules to be stored
in various formats, such as files (e.g. /etc/hosts.allow
and /etc/hosts.deny) or in SQL tables. Note that the
mod_wrap2 module does not require or use the
standard tcpwrappers libwrap library, and instead implements
the same functionality internally (in order to support SQL-based access rules).
Please read the usage documentation for more details.
This module is contained in mod_wrap2.c,
mod_wrap2.h, and in the submodules source files, for
ProFTPD 1.3.x. These modules are not enabled by default. Installation
notes follow the directive documentation.
The most current version of mod_wrap2's submodules supports
storage of access table information in various formats:
The most current version of mod_wrap2 is distributed with the
ProFTPD source code.
Author
Please contact TJ Saunders <tj at castaglia.org> with any
questions, concerns, or suggestions regarding this module.
Thanks
Many, many thanks to Wietse Venema for writing the tcpwrappers
package and its libwrap library, from which this module drew
much of its code.
2002-12-12: Thanks to Steve Grubb for pointing out a few cases where
interrupted functions were not being properly handled, and for reviewing
the module code.
Directives
Syntax: WrapAllowMsg mesg
Default: None
Context: server config, <VirtualHost, <Global>, <Anonymous>
Module: mod_wrap2
Compatibility: 1.3.1rc1 and later
The WrapAllowMsg directive configures a message that will be
added to proftpd's response to the connecting client when that
client is allowed by mod_wrap2's access check. In the
mesg parameter, the magic cookie '%u' is replaced with the username
specified by the client during login.
Example:
WrapAllowMsg "User '%u' allowed by access rules"
Syntax: WrapDenyMsg mesg
Default: None
Context: server config, <VirtualHost, <Global>, <Anonymous>
Module: mod_wrap2
Compatibility: 1.3.1rc1 and later
The WrapDenyMsg directive configures a message that will be
sent to the connecting client when that client is denied by
mod_wrap2's access check, and disconnected. In the mesg
parameter, the magic cookie '%u' is replaced with the username specified by
the client during login.
Example:
WrapDenyMsg "User '%u' denied by access rules"
Syntax: WrapEngine on|off
Default: None
Context: server config, <VirtualHost>, <Global>
Module: mod_wrap2
Compatibility: 1.3.1rc1 and later
The WrapEngine directive enables or disables the module's runtime
access control engine. If it is set to off this module does no runtime
processing at all. Use this directive to disable the module instead of
commenting out all mod_wrap2 directives.
Syntax: WrapGroupTables group-AND-expression source-type:allow-source-info source-type:deny-source-info [source-type:options-source-info]
Default: None
Context: server config, <VirtualHost, <Global>, <Anonymous>
Module: mod_wrap2
Compatibility: 1.3.1rc1 and later
The WrapGroupTables directive configures the information necessary
for mod_wrap2 to locate and use the tables containing the access
rules for specific groups.
The group-AND-expression parameter is a logical AND expression, which
means that the connecting user must be a member of all the groups
listed for this directive to apply. Group names may be negated with a
! prefix.
The next two parameters specify two tables, an allow and a deny table, each of
which contain the IP addresses, networks or host/network masks to be allowed or
denied.
Please consult the relevant submodule documentation
for details on that module's syntax for specifying tables. The service name
for which mod_wrap2 will look in the indicated access tables is
"proftpd" by default; this can be configured via the
WrapServiceName directive.
See also:
WrapServiceName,
WrapTables,
WrapUserTables
Syntax: WrapLog file|"none"
Default: None
Context: server config, <VirtualHost>, <Global>
Module: mod_wrap2
Compatibility: 1.3.1rc1 and later
The WrapLog directive is used to specify a log file for
mod_wrap2 reporting, and can be done a per-server basis.
The file parameter must be the full path to the file to use for
logging. Note that this path must not be to a world-writeable
directory and, unless AllowLogSymlinks is explicitly set to
on (generally a bad idea), the path must not be a symbolic
link.
If file is "none", no logging will be done at all; this
setting can be used to override a WrapLog setting inherited from
a <Global> context.
Syntax: WrapOptions opt1 ...
Default: None
Context: server config, <VirtualHost>, <Global>
Module: mod_wrap2
Compatibility: 1.3.4rc1 and later
The WrapOptions directive is used to configure various optional
behavior of mod_wrap2. Note: all of the configured
WrapOptions parameters must appear on the same line in the
configuration; only the first WrapOptions directive that appears
in the configuration is used.
Example:
WrapOptions CheckOnConnect
The currently implemented options are:
CheckAllNames
This causes mod_wrap2 to check all of the known
DNS names for the client IP address against the DNS names/patterns
in the access rules, rather than just checking the first DNS name
returned for the client IP address.
CheckOnConnect
This causes mod_wrap2 to check the allow/deny tables when
the client first connects, rather than waiting until the client has
authenticated before checking the access rules. This means that
per-user/group allow/deny tables, and the use of the tilde (~) notation
in table paths, is not supported when this option is used.
In addition, if mod_wrap2_sql is used, the order in
which that module is loaded is very important. The mod_sql
module must appear after the mod_wrap2 module
in the --with-modules configure option, e.g.:
--with-modules=mod_wrap2:mod_wrap2_sql:mod_sql:mod_sql_mysql
Or, if you are using shared/DSO modules, then you must ensure that
the modules are loaded in the correct order via LoadModule:
...
LoadModule mod_wrap2.c
LoadModule mod_wrap2_sql.c
...
LoadModule mod_sql.c
LoadModule mod_sql_mysql.c
...
You will also need to ensure that mod_sql creates a
database connection at connect time, using the PERCONNECTION
connection policy; see
SQLConnectInfo for
more details:
SQLConnectInfo database user password PERCONNECTION
Without this, the database connection will not be created at connect
time, and the mod_wrap2 module will be unable to check
any allow/deny rules stored in SQL tables when the client connects.
Syntax: WrapServiceName name
Default: WrapServiceName proftpd
Context: server config, <VirtualHost>, <Global>
Module: mod_wrap2
Compatibility: 1.3.1rc1 and later
WrapServiceName is used to configure the name of the service under
which mod_wrap2 will check the allow/deny tables. By default, this
is the name of the program started, i.e. "proftpd". However,
some administrators may want to use a different, more generic service name,
such as "ftpd"; use this directive for such needs. The lookup
using the configured name is case-sensitive.
Syntax: WrapTables source-type:allow-source-info source-info:deny-source-info
Default: None
Context: server config, <VirtualHost, <Global>, <Anonymous>
Module: mod_wrap2
Compatibility: 1.3.1rc1 and later
The WrapTables directive configures the information necessary
for mod_wrap2 to locate and use the tables containing the access
rules for all clients.
The two parameters specify two tables, an allow and a deny table, each of which
contain the IP addresses, networks or host/network masks to be allowed or
denied.
Please consult the relevant submodule documentation
for details on that module's syntax for specifying tables. The service name
for which mod_wrap2 will look in the indicated access tables is
"proftpd" by default; this can be configured via the
WrapServiceName directive.
See also:
WrapGroupTables,
WrapServiceName,
WrapUserTables
Syntax: WrapUserTables user-OR-expression source-type:allow-source-info source-type:deny-source-info [source-type:option-source-info]
Default: None
Context: server config, <VirtualHost, <Global>, <Anonymous>
Module: mod_wrap2
Compatibility: 1.3.1rc1 and later
The WrapUserTables directive configures the information necessary
for mod_wrap2 to locate and use the tables containing the access
rules for specific users.
The user-OR-expression parameter is a logical OR expression, which
means that the connecting user can be any the users listed for this
directive to apply. User names may be negated with a ! prefix.
The next two parameters specify two tables, an allow and a deny table, each of
which contain the IP addresses, networks or host/network masks to be allowed or
denied.
Please consult the relevant submodule documentation
for details on that module's syntax for specifying tables. The service name
for which mod_wrap2 will look in the indicated access tables is
"proftpd" by default; this can be configured via the
WrapServiceName directive.
See also:
WrapGroupTables,
WrapServiceName,
WrapTables
To use mod_wrap2's functionality, you must first define the tables
that together contain the access rules. Access rules are composed of
daemon lists, client lists, and optional options lists.
daemon lists are used so that the access rules can be configured for
multiple daemons; mod_wrap2 ignores all daemons except that
configured for proftpd. client lists are the heart of
the access rules, specifying the host names, IP addresses, etc to
be allowed or denied. The handling of options lists is done only if
mod_wrap2 is configured with the
--enable-wrapper-options option.
There is a built-in precedence to the WrapUserTables,
WrapGroupTables, and WrapTables directives, if all
are used. mod_wrap2 will look for applicable
WrapUserTables for the connecting user first. If no applicable
WrapUserTables are found, mod_wrap2 will search for
WrapGroupTables which pertain to the connecting user. If not
found, mod_wrap2 will then look for the server-wide
WrapTables directive. This allows for access control to be set
on a per-server basis, and allow for per-user or per-group access control
to be handled without interfering with the overall server access rules.
When checking the tables, mod_wrap2 always checks the allow
table first. If the client has been explicitly allowed by the rules in
that table, processing stops and mod_wrap2 allows the client
to continue the session. If not explicitly allowed, mod_wrap2
will then check the deny table's access rules. If the client has been
explicitly denied by rules in that table, mod_wrap2 will
disconnect the client. By default, if neither explicitly allowed or
explicitly denied, mod_wrap2 will allow the client to continue.
In addition to the various formats supported by the
submodules, there is a special source type:
"builtin". This is used in the situations where the administrator
wishes to configure "mostly closed" access rules, the most common
situation. For example, if all clients are to be denied by
mod_wrap2 by default, unless that client is granted access via an
allow table entry, then the administrator can use:
builtin:all
as the deny table parameter (e.g. in a WrapUserTables,
WrapGroupTables, or WrapTables directive), rather
than configuring a static deny table that always says ALL.
When checking access rules, the check terminates when the first match is
found. A client list is a list of one or more host names, host
addresses, patterns or wildcards (see below) that will be matched against the
client host name or address. The more complex daemon@host and
user@host forms are explained in the sections on server endpoint
patterns and on client username lookups, respectively. With the exception of
NIS/YP netgroup lookups, all access control checks are case insensitive.
Patterns
The access control language implements the following patterns:
- A string that begins with a `.' character. A host name is matched if the
last components of its name match the specified pattern. For example, the
pattern
.castaglia.org matches the host name
golem.devlan.castaglia.org.
- A string that ends with a `.' character. A host address is matched if its
first numeric fields match the given string. For example, the pattern
131.155. matches the address of (almost) every host on the
Eindhoven University network (131.155.x.x).
- A string that begins with an `@' character is treated as an NIS (formerly
YP) netgroup name. A host name is matched if it is a host member of the
specified netgroup. Netgroup matches are not supported for client user
names. Note that
mod_wrap2 must be configured for NIS
support for netgroup lookups to occur.
- An expression of the form n.n.n.n/m.m.m.m is interpreted as
an IPv4
net/mask pair. An IPv4 address is matched if the
net portion is equal to the bitwise AND of the address and the
mask portion. For example, the net/mask pattern
131.155.72.0/255.255.254.0 matches every address in the range
131.155.72.0 through 131.155.73.255.
- An expression of the form [address]/number is interpreted as
an IPv6
net/mask pair. An IPv6 address is matched if the
first number bits match the rule address. For example,
[3ffe:505:2:1::]/64 matches every address in the range
3ffe:505:2:1:: through 3ffe:505:2:1:ffff:ffff:ffff:ffff:.
- Wildcards `*' and `?' can be used to match hostnames or IP addresses.
This method of matching cannot be used in conjunction with
net/mask matching, hostname matching beginning with `.' or
IP address matching ending with `.'.
Wildcards
The access control language supports explicit wildcards:
- ALL
The universal wildcard, always matches.
- LOCAL
Matches any host whose name does not contain a dot character.
- UNKNOWN
Matches any user whose name is unknown, and matches any host whose name or
address are unknown. This pattern should be used with care: host names may
be unavailable due to temporary name server problems.
- KNOWN
Matches any user whose name is known, and matches any host whose name and
address are known. This pattern should be used with care: host names may be
unavailable due to temporary name server problems.
- PARANOID
Matches any host whose name does not match its address, before looking
at the access control tables.
Operators
- EXCEPT
Intended use is of the form:
list1 EXCEPT list2
This construct matches anything that matches list1 unless it
matches list2. The EXCEPT operator can be used in daemon
lists and client lists. The EXCEPT operator can be nested: if
the control language would permit the use of parentheses:
a EXCEPT b EXCEPT c
would parse as
(a EXCEPT (b EXCEPT c))
Server Endpoint Patterns
In order to distinguish clients by the network address that they connect to,
use patterns of the form:
process-name@host-pattern : client-list ...
Patterns like these can be used when the machine has different Internet
addresses with different Internet hostnames. Service providers can use this
facility to offer FTP, GOPHER or WWW archives with Internet names that may even
belong to different organizations. Some systems can have more than one
Internet address on one physical interface.
The host-pattern obeys the same syntax rules as host names and addresses
in client lists.
Client Username Lookup
When the client host supports the RFC 931 protocol, the proftpd
daemon can retrieve additional information about the owner of a connection.
Client username information, when available (i.e. when
IdentLookups are not disabled), is logged together with the client
host name, and can be used to match patterns like:
daemon-list : ... user-pattern@host-pattern ...
A user-pattern has the same syntax as a daemon pattern, so the same
wildcards apply (netgroup membership is not supported). One should not get
carried away with username lookups, though:
- The client username information cannot be trusted when it is needed
most, i.e. when the client system has been compromised. In
general, ALL and (UN)KNOWN are the only user name patterns that make sense.
- Username lookups are possible only when the client host runs a suitable
daemon; in all other cases the result is "unknown".
This section describes optional options list portion the access control
language described above. The options list syntax uses the following
format:
opt1 : opt2 ...
Any `:' characters within options should be protected with a backslash.
An option is of the form "keyword" or
"keyword value". Options are processed in the
specified order. For the sake of backwards compatibility with earlier
versions, a `=' is permitted between keyword and value.
- ALLOW
Grant service. This option must appear at the end of a rule.
- DENY
Deny service. This option must appear at the end of a rule.
The allow and deny keywords make it possible to keep all access control
rules within a single file, for example in the hosts.allow
file. To permit access from specific hosts only:
ALL: .friendly.domain: ALLOW
ALL: ALL: DENY
To permit access from all hosts except a few trouble makers:
ALL: .bad.domain: DENY
ALL: ALL: ALLOW
Notice the leading dot on the domain name patterns.
- nice [number]
Change the nice value of the process (default 10). Specify a positive
value to spend more CPU resources on other processes.
- setenv name=value
Place a name=value pair into the process environment. The
value may contain whitespace (but leading and trailing blanks are stripped
off).
Diagnostics
When a syntax error is found in an options list, the error is reported in the
WrapLog and the access option will be ignored.
Follow the usual steps for using third-party modules in ProFTPD:
$ ./configure --with-modules=wrap-modules
$ make
$ make install
where wrap-modules will depend on the types of access tables you wish
to support.
For file-based access tables, include the mod_wrap2_file
submodule, e.g.:
mod_wrap2:mod_wrap2_file
For SQL-based access tables, include the mod_wrap2_sql
submodule, e.g.:
mod_wrap2:mod_wrap2_sql
And, if you wish to support both file- and SQL-based access tables, use:
mod_wrap2:mod_wrap2_file:mod_wrap2_sql
Note that SQL tables require that a correct installation of mod_sql
(and any of its backend modules) also be used. Consult the mod_sql
documentation for installation instructions for that module.
© Copyright 2000-2016 TJ Saunders
All Rights Reserved
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