IRC Hacks [Electronic resources] نسخه متنی

Hack 95 Set Up Your Own IRC Server for Unix/Linux

Whether it's for testing bots
or chatting with your mates, set up your own server for the ultimate
power and sense of achievement.

At some point you may want
to run your own servermaybe to test a bot without disturbing
other users, to learn how the IRC operator commands work, or as a
place for your friends to chat. It isn't easy to run
your own server, as there is a lot to understand and configure, but
it is a good learning experience and quite good fun too!

IRC servers are often called IRC daemons, which are also typically
abbreviated as ircds. The code that most IRC servers are based on
dates back to the original ircd. Jarkko Oikarinen wrote this in 1988
at the University of Oulu in Finland. The code is licensed under the
GPL, and therefore developers are free to extend it under that
license.

You have a large choice of ircds. Many of these are listed on
http://directory.google.com/Top/Computers/Software/Internet/Servers/Chat/IRC.
A lot of IRC networks have their own ircd. Some make small
modifications to another ircd, while others may add major new
features. Although the server-to-server communication format is
documented in RFC 1459, modern IRC servers do not strictly adhere to
it, as many extensions have been made (and continue to be made). If
you are connecting to an existing IRC network, you will have to use
an ircd that is compatible.

One of the most popular and full-featured ircds is Unreal. It has versions for both Windows
and Unix operating systems. This hack will guide you through
installing and configuring it. There is a lot to learn, so this hack
will just help you with the basicssetting up a single server
with the most basic configuration needed to run. You should read the
Unreal documentation and learn about all the features if you are
serious about running an ircd for public use.

15.2.1 Installing Unreal

Download Unreal from http://www.unrealircd.com. If you have
downloaded the version for Windows, it should be already compiled,
and you can skip to the configuration stage. Although you can compile
it under Windows, it is much easier to use the precompiled version,
so this section will focus on Unix-based systems.

You may need to change some of the filenames depending on which
version you download. Extract the source with the
tar command:

% tar zxvf Unreal3.2.tar.gz

Then change directory to the extracted directory:

% cd Unreal3.2

To compile the ircd, you first need to configure it. This is so you
can choose where to install it and set some compile-time options:

% ./Config

This will ask you some questions and then run the configure script
for you. Accepting the defaults is fine, unless you want one of the
features that are disabled by default.

Then to compile the ircd:

% make

Normally, the ircd is run from within the source directory; however,
if you specified a different location when you ran the
./Config command, you will also need to run
make install like so:

% make install

Traditional ircd configuration files have followed a format in which
each line is identified by a single letter and followed by fields
separated by colons. The advantage of this is it is easy to write the
parser for the file. Unfortunately, it leads to rather cryptic
configuration files, because you need to know what each letter stands
for and what order the fields should be in. Some of these are easy to
remember, as some letters are commonly usedeven by users who
may have no idea of their true origin. For example, K-lines (server
bans on an address) are named after their format in the configuration
file.

Fortunately, Unreal 3.2 has a new-style configuration format that is
much more verbose, allowing a clearer configuration file.

To make a configuration file, copy the file
doc/example.conf to
unrealircd.conf. Open this file with your
favorite text editor. The configuration file may seem very long and
scary at first. Well, it is a bit scary, but a lot of the file is
full of comments that explain what all of the options do. Comments
are text enclosed with /* */, like C comments.

Each part of the configuration is separated into blocks. A block is a
set of configuration variables that are related. Taking the
"me" block as an example, the
format of the configuration file can be explained:

me {
name "irc.example.com";
info "An example server";
numeric 1;
};

The first line has the name of the block and a {
symbol to show it is the start of the block. The next line sets the
variable name to the string
irc.example.com. Strings must be enclosed in
quotation marks, as shown in the code block. All statements must end
with a semicolon. Numbersunlike stringsshould not be
quoted, as shown by the numeric variable
1. A closing } is used to end
the blocknotice that the block requires a semicolon at the
end. Each line with a variable on it is indented for clarity. While
not essential, this makes it much easier to read the file when you
have blocks nested within other blocks.

The first block in the example configuration file is the previously
mentioned "me" block. The name
should be a valid DNS hostname. This could be the hostname of the
machine the ircd will run on or a name such as irc.example.com. The
info is a description of the server and can be seen by clients when
they execute the /whois command on a connected
user, among other places. The numeric is a number between 1 and 255
that is unique to this server in a network; 1 is fine if this is the
only or the first server in a network. You should change the value of
these to ones suitable for your network.

The "admin" block specifies what
gets shown when a user runs the /admin command. It
is common practice to put contact information here.

Class blocks define various values such as times and the number of
clients that can connect. They are referred to by other blocks, such
as server connections and client allow blocks. They are the first
blocks that can exist more than oncethey must also be given a
name on the same line as the block name. However, this name is not
quoted like other strings. The default classes should be fine to
start with, so there is no need to change anything.

The "allow" blocks allow clients to
connect. Unless you want to limit your server to specific users, the
default is fine.

Each IRC operator on the server must have an
"oper" block; you can edit the
example for the first operator. The account name goes after the oper
in the block name. The "from" is a
list of user hosts allowed to use this operator block. This is a
standard IRC host mask (without a nickname) and can include the
* wildcard. It is a good idea to change the
password to something more secure. Flags specify what the operator is
allowed to doa netadmin is allowed to do most things and is
probably what you want for yourself. It's up to you
what permissions you give to other users. To become an IRC operator,
you should connect with your IRC client and type:

/oper  account-name password 

The "listen" block defines the
ports the IRC server will listen on. Port 6667 is the standard IRC
port and what most people expect to connect to, so
it's a good idea to leave this as it is. Obviously,
you can open extra ports for whatever reasonmaybe some
institutions block traffic on port 6667, so you can be kind and open
up another port number as well. If you chose to enable SSL during the
./Config process, you will also need to specify an
SSL port.

The "link" and
"ulines" blocks are used for
linking other servers and Services to the server. The link defines
the password and remote address of the server and will be covered in
the next hack on Services, so you can comment out the link block for
now. A ulines block allows Services to change modes on channels.

The "drpass" block defines
passwords for the /restart and
/die commands, which restart and stop the ircd,
respectively. The main purpose of each password is merely to prevent
accidental usage of the commands, as the user must be an IRC operator
to be able to run these commands.

Several other blocks provide extra functionality. The defaults for
these should be fine, so don't worry too much. These
options cover logging, aliases, tld (display different MOTDs to
different users), banning, exceptions, deny (block some DCC file
types), and vhost (allow users to change host via a password system).
You should comment out features you don't intend to
useat the very least, you will need to remove tld or create
the files it needs and remove the default exception.

At the end of the example configuration file, you'll
find the "set" blocks. There are
some very important settings to make here. The first set block is
network settings. The network settings in the example configuration
file are for a network called ROXnet, and you should change the names
to something more appropriate. It's best to use a
valid domain name for the hostnames. However, apart from the
default-server setting, the hostnames themselves do not need to be
valid hostnames, as they are used only within IRC. The cloak-keys
should be set to three different random values greater than
10000they are needed so that Unreal's masked
hosts are secure.

The second set block deals with settings specific to the server. The
"kline" address should be set to
something valid, and the DNS server should be set to the IP address
of your DNS server. If you are unsure what the IP address of your DNS
server is, look at the file /etc/resolv.conf on
a Unix system. On Windows 2000 and later versions, you can open a
command prompt and run the command ipconfig /all.
Older Windows machines will display their IP address and DNS server
if you run winipcfg.

Now you have most of the settings sorted out, so the server should be
ready to run. To test it on a Unix system, run:

% ./unreal start

When the server starts up, you should see something like Figure 15-1.

Figure 15-1. Running Unreal under Linux

Windows users can just start the Unreal ircd program on Windows. When
it starts, it will display a control panel as in Figure 15-2. If there is an error, it should give you some
idea of the problem, so check the configuration file carefully to see
if you can fix it. If the server has started correctly, you should be
able to connect to the server by connecting to localhost:6667 with
any IRC client.

Figure 15-2. Unreal for Windows has a control panel when running

Once you have connected, you should be able to become an IRC operator
using the /oper command, with the username and password
that you set in the file. There are lots of IRC operator
commands. Typing /helpop opercmd will show a
listing, and then /helpop
command will show help on that particular

command.

David Leadbeater