danted.conf - Dante server configuration file syntax

The configuration file for the Dante server controls both access controls and logging. It is divided into two parts, server settings and rules. A line can be commented using the standard comment character #.

The server settings control the generic behaviour of the server. Each keyword is separated from it's value by a ':' character.

child.maxidle

Maintains a maximum on how many children of each type can remain idle. Used to reduce the amount of idle processes after a "client burst" has occured. The default is 0 (no maximum).

compatibility

With the sameport keyword, the server attempts to use the same port on the server and the client. This functionality is the default, but when this option is given it will also be done with privileged ports. The reuseaddr keyword might solve problems when the bind extension is used but the effects of enabling reuseaddr is currently unknown, do not enable it unless you understand the effects.

connecttimeout

The number of seconds a client has to send the request after a connect. Set it to 0 for forever.

external

The address to be used for outgoing connections. The address given may be either a IP address or a interfacename. Can be given multiple times for different addresses.

external.rotation

If more than one external address is given, this governs which address is selected. Valid values are none (the default) and route. The latter might require you to set user.privileged to root.

Note that route might create problems for ftp-clients using active ftp if the Dante bind extension is enabled for the ftp-client.

internal

The internal addresses. Connections will only be accepted on these addresses. The address given may be either a IP address or a interfacename.

iotimeout

The number of seconds an established connection can be idle. Set it to 0 for forever.

logoutput

This value controls where the server sends logoutput. It can be either syslog[/facility], stdout, stderr, a filename, or a combination.

method

A list of acceptable authentication methods for socks-rules, in order of preference. Supported values are username, none, rfc931 and pam. This list is used as the default for all coming rules until changed. Then the changed list is used as the default for the next rules.

If a method is not set in this list it will never be selected.

See the section on methods for a explanation of the different methods.

clientmethod

A list of acceptable authentication methods for client-rules, in order of preference. These are the authenticationmethods that can provide authentications based on just the client's TCP connection. Supported values are none, rfc931 and pam. This list is used as the default for all coming rules until changed. Then the changed list is used as the default for the next rules. The default value is none.

If a method is not set in this list it will never be selected.

srchost

With the nomismatch keyword, the server will not accept connects from addresses having a mismatch between DNS address and hostname. Default is to accept them. With the nounknown keyword, the server will not accept connects from addresses without a DNS record. Default is to accept them.

user.privileged

Username which will be used for doing privileged operations.

user.notprivileged

User which the server runs as most of the time.

user.libwrap

User used to execute libwrap commands.

The following modules are supported by Dante. Modules are purchased separately from Inferno Nettverk A/S. See the Dante homepage for more information.

redirect

The redirect module gives you control over what addresses the server will use on behalf of the client and allows you to both redirect client requests to a different addresses aswell as control the range of addresses and ports to be used on behalf of the client.

It can also be used to restrict the number of concurrent sessions from each client.

bandwidth

The bandwidth module gives you control over how much bandwidth the Dante server uses on behalf of different clients.

The Dante server supports the following methods. Some installations of Dante may support only a subset of these.

none

The method requires no form of authentication.

username

The method requires the client to provide a username and password. This must match the username and password given in the system passwordfile.

rfc931

The method requires the client host to provide a rfc931 ("ident") reply for the connecting client. The name given in the reply must be present in the password database.

pam

The method requires the available clientdata to match against the pam database.

Each address field can consist of a IP address (and where meaningful, a netmask, separated from the IP address by a '/' sign.), a hostname, or a domainname (designated so by the leading '.'). Each address can be followed by a optional port specifier.

There are two sets of rules and they work at different levels. Rules prefixed with client are checked first and are used to see if the client is allowed to connect to the Dante server. We will call them "client-rules". It is especially important that these do not use hostnames but only IP addresses, both for security and performance reasons. These rules work at the TCP/IP level.

The other rules, which we will call "socks-rules" are a level higher and are checked after the client connection has been accepted by the client-rules. The socks-rules are used to evaluate the socks request that the client sends. They thus work at the socks protocol level.

Both set of rules start with a pass/deny keyword (the client-rules have "client" prefixed to the pass/deny keyword) which determines if connections matching the rule are to pass or be blocked. Both set of rules also specify a from/to address pair which gives the addresses the rule will match.

In both contexts, from means the clients address.

In the client-rule context, to means the address the request is accepted on, i.e. the address the Dante server listens on.

In the socks-rule context, to means the client's destination address, as formulated in the client's proxy request.

In addition to the addresses there is a set of optional keywords which can be given. There are two forms of keywords, conditions and actions. For each rule, all conditions are checked and if they match the request, the actions are executed.

The list of condition keywords is: from, to, command, method, protocol, proxyprotocol, user.

The list of actions keywords is: bandwidth, libwrap, log and redirect.

The format and content of the rules is identical, but client-rules may contain only a subset of the socks-rules. More concrete, they may not contain any keywords related to the socks protocol.

The contents of a client-rule is:

from

The rule applies to requests coming from the address given as value.

to

The rule applies to requests going to the address given as value.

port

Parameter to from, to and via. Accepts the keywords eq/=, neq/!=, ge/>=, le/<=, gt/>, lt/< followed by a number. A portrange can also be given as "port <start #> - <end #>", which will match all port numbers within the range <start #> and <end #>.

libwrap

The server will pass the line to libwrap for execution.

log

Used to control logging. Accepted keywords are connect, disconnect, data, error and iooperation.

user

The server will only accept connections from users matching one of the names given as value. If no user value is given, everyone in the passwordfile will be matched. The rule must also allow usernamebased methods.

method

Require that the connection be "authenticated" using one of the given methods.

pam.servicename

Which servicename to use when involving pam. Default is "sockd".

The contents of a socks-rule is:

from

The rule applies to requests coming from the address given as value.

to

The rule applies to requests going to or using the address given as value. Note that the meaning of this address is affected by command.

port

Parameter to from, to and via. Accepts the keywords eq/=, neq/!=, ge/>=, le/<=, gt/>, lt/< followed by a number. A portrange can also be given as "port <start #> - <end #>", which will match all port numbers within the range <start #> and <end #>.

bandwidth

The clients matching this rule will all share this amount of bandwidth.

command

The rule applies to the given commands. Valid commands are bind, bindreply, connect, udpassociate and udpreply. Can be used instead of, or to complement, protocol.

libwrap

The server will pass the line to libwrap for execution.

log

Used to control logging. Accepted keywords are connect, disconnect, data and iooperation.

method

Require that the connection be established using one of the given methods. method always refers to the source part of the rule. Valid values are the same as in the global method line.

pam.servicename

What servicename to use when involving pam. Default is "sockd".

protocol

The rule applies to the given protocols. Valid values are tcp and udp. It is recommended that the command form is used since it provides more accuracy in defining rules.

proxyprotocol

The rule applies to requests using the given proxyprotocol. Valid proxyprotocols are socks_v4 and socks_v5.

redirect

The source and/or destination can be redirected using the redirect statement. The syntax of the statement is as follows:

redirect from: ADDRESS

redirect to: ADDRESS

The semantics of from and to vary according to command and should be intuitive enough.

user

The server will accept connections from users matching one of the names given as value. If no user value is given, everyone in the passwordfile will be matched. The rule must also allow usernamebased methods.

See the example directory in the distribution.

/etc/danted.conf	Dante server configuration file.
/etc/passwd	file used when checking username/passwords.

For Inferno Nettverk A/S, Norway: Michael Shuldman <michaels@inet.no>: Design and implementation. Karl-Andre' Skevik <karls@inet.no>: Autoconf and porting.

danted(8), hosts_access(5)

Information about new releases and other related issues can be found on the Dante WWW home page at http://www.inet.no/dante.