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Manual Pages for UNIX Operating System command usage for man hosts_options

File Formats HOSTS_OPTIONS(4)

NAME

hosts_options - host access control language extensions

DESCRIPTION

This document describes optional extensions to the language

described in the hosts_access(4) document. The extensions

are enabled at program build time. For example, by editing

the Makefile and turning on the PROCESS_OPTIONS compile-time

option. The extensible language uses the following format:

daemon_list : client_list : option : option ...

The first two fields are described in the hosts_access(4)

manual page. The remainder of the rules is a list of zero or more options. 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. Some options

are subjected to % substitutions. For the sake of

backwards compatibility with earlier versions, an "=" is permitted between keyword and value. LOGGING severity mail.info severity notice Change the severity level at which the event will be logged. Facility names (such as mail) are optional, and

are not supported on systems with older syslog imple-

mentations. The severity option can be used to emphasize or to ignore specific events. ACCESS CONTROL allow deny Grant (deny) service. These options 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: SunOS 5.10 Last change: 1

File Formats HOSTS_OPTIONS(4)

ALL: .bad.domain: DENY ALL: ALL: ALLOW Notice the leading dot on the domain name patterns. RUNNING OTHER COMMANDS

spawn shell_command

Execute, in a child process, the specified shell com-

mand, after performing the % expansions

described in the hosts_access(4) manual page. The com-

mand is executed with stdin, stdout and stderr con-

nected to the null device, so that it won't mess up the conversation with the client host. Example:

spawn (/some/where/safe_finger -l @%h | /usr/ucb/mail root) &

executes, in a background child process, the shell com-

mand "safe_finger -l @%h | mail root" after replacing

%h by the name or address of the remote host.

The example uses the "safe_finger" command instead of

the regular "finger" command, to limit possible damage

from data sent by the finger server. The "safe_finger"

command is part of the daemon wrapper package; it is a wrapper around the regular finger command that filters the data sent by the remote host.

twist shell_command

Replace the current process by an instance of the

specified shell command, after performing the %

expansions described in the hosts_access(4) manual

page. Stdin, stdout and stderr are connected to the client process. This option must appear at the end of a rule. To send a customized bounce message to the client instead of running the real ftp daemon: in.ftpd : ... : twist /bin/echo 421 Some bounce message For an alternative way to talk to client processes, see the banners option below. To run /some/other/in.telnetd without polluting its

command-line array or its process environment:

in.telnetd : ... : twist PATH=/some/other; exec in.telnetd

Warning: in case of UDP services, do not twist to com-

mands that use the standard I/O or the read(2)/write(2) routines to communicate with the client process; UDP

requires other I/O primitives. SunOS 5.10 Last change: 2

File Formats HOSTS_OPTIONS(4)

NETWORK OPTIONS keepalive Causes the server to periodically send a message to the client. The connection is considered broken when the client does not respond. The keepalive option can be useful when users turn off their machine while it is still connected to a server. The keepalive option is not useful for datagram (UDP) services.

linger number_of_seconds

Specifies how long the kernel will try to deliver not-

yet delivered data after the server process closes a connection.

USERNAME LOOKUP

rfc931 [ timeout_in_seconds ]

Look up the client user name with the RFC 931 (TAP, IDENT, RFC 1413) protocol. This option is silently ignored in case of services based on transports other than TCP. It requires that the client system runs an

RFC 931 (IDENT, etc.) -compliant daemon, and may cause

noticeable delays with connections from non-UNIX

clients. The timeout period is optional. If no timeout

is specified a compile-time defined default value is

taken. MISCELLANEOUS banners /some/directory Look for a file in `/some/directory' with the same name as the daemon process (for example in.telnetd for the telnet service), and copy its contents to the client.

Newline characters are replaced by carriage-return new-

line, and % sequences are expanded (see the

hosts_access(4) manual page).

The tcp wrappers source code distribution provides a sample makefile (Banners.Makefile) for convenient banner maintenance.

Warning: banners are supported for connection-oriented

(TCP) network services only. 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 environ-

ment. The value is subjected to % expansions

and may contain whitespace (but leading and trailing blanks are stripped off). SunOS 5.10 Last change: 3

File Formats HOSTS_OPTIONS(4)

Warning: many network daemons reset their environment before spawning a login or shell process. umask 022 Like the umask command that is built into the shell. An umask of 022 prevents the creation of files with group and world write permission. The umask argument should be an octal number. user nobody user nobody.kmem Assume the privileges of the "nobody" userid (or user "nobody", group "kmem"). The first form is useful with inetd implementations that run all services with root privilege. The second form is useful for services that need special group privileges only. DIAGNOSTICS When a syntax error is found in an access control rule, the error is reported to the syslog daemon; further options will be ignored, and service is denied.

ATTRIBUTES

See attributes(5) for descriptions of the following attri-

butes:

_______________________________________

| ATTRIBUTE TYPE | ATTRIBUTE VALUE|

|____________________|__________________|_

| Availability | SUNWtcpd |

|____________________|__________________|_

| Interface Stability| Committed |

|____________________|_________________|

NOTES

Source for tcp_wrappers is available in the SUNWtcpdS pack-

age. SunOS 5.10 Last change: 4

Manual Pages for UNIX Operating System command usage for man hosts_options

NAME

hosts_options - host access control language extensions

DESCRIPTION

USERNAME LOOKUP

SEE ALSO

ATTRIBUTES

| ATTRIBUTE TYPE | ATTRIBUTE VALUE|