Internet Services
This help page is incomplete
Introduction
This module allows you to manage and setup internet services such as
telnet, ftp and finger. Every internet service
has a name, port number and protocol (such as telnet on
tcp port 23). Many services also have a server program to handle
network connections to that services.
Services with an associated program are controlled by the Unix
inetd daemon, which listens for network connections on behalf of
all its services. When a connection is received, the server program is
started to handle data from the new connection.
Not all internet services are managed by this module. Servers that receive
many connections such as HTTPD, SMB or NFS are run separately to avoid
having to start a new process for each request. These services can be
configured using other Webmin modules, such as Samba
or Apache.
The main page for this module lists all the internet and RPC services
on your system. Services with a program assigned are displayed in bold.
The list of internet services, RPC services and programs are taken from
the files /etc/services, /etc/rpc and
/etc/inetd.conf.
Creating a New Service
To create a new internet service, click on the Create New Service
link below the list of active services. This will take you to a form
in which the details of the new service can be entered :
- Service Name
Every service must have a unique name and protocol pair.
This means that two services can have the same name only
if they use different protocols.
- Protocol
The communications protocol used by this service. Almost all
internet services use the TCP protocol, and the rest
use UDP.
- Port
Every service has a port number which must be unique within
the protocol used by the service. The port number must be between
0 and 65535 for both TCP and UDP.
- Aliases
A list of alternative names used to refer to this service. An
alias cannot be already used as the name or alias of an existing
service with the same protocol.
Internet service names can be used instead of hostnames in commands
such as telnet. For example, you can type telnet foo.bar.com smtp to connect to port 25 on the host foo.bar.com, assuming
the smtp internet service is defined correctly.
For services with an associated program, you must choose the Use the
program below option ???
- Program
Some rare services are handled internally by inetd.
However, for almost all new services that you create the full
path to the program to execute for the service should be given
here.
- Arguments
Command line arguments to pass to the program above. The first
argument should be the program name, and the rest other parameters
to pass.
- Wait mode
This determines if inetd will wait until the program
is complete before starting any others or not. For most services,
this should be Don't wait.
- Execute as
The username of the user the server program should be run as.
Most servers will need to be run as root.
When a new service is added, it will not take effect immediately. You must
click the Restart Inetd button on the main page for the addition
to be applied.
Editing an Existing Service
To edit a service, click on the service name from the list on the main page.
This will display the same form used for creating a service to allow you
to edit the service details. You can also click on the Delete
button at the bottom of the page to delete the service.
Be careful when editing or deleting existing system services such as
telnet or ftp. Changing these may make it impossible
to login to your machine (or worse).
When a service is modified, it will not take effect immediately. You must
click the Restart Inetd button on the main page for the changes
to be applied.
Creating and Editing RPC Programs
In general, you will never need to create or edit RPC programs on your
system. However, if you do the procedure is similar to creating and
editing internet services.
The form for editing and creating RPC programs will always contain at
least the following fields :
- Program Name
A unique name for this RPC program (within the same protocol).
- Number
Every RPC program has a unique program number, determined when
the program is written.
- Aliases
Other names that can be used to refer to this RPC program.
Some operating systems (such as Solaris) allow a server program to be
associated with an RPC service. This program will be run by inetd
when it receives a request for the program.
If your system supports RPC server programs started by inetd, the following
fields will also be visible :
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