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Setting Up a Nethack 3.6.6 Server

A guide on how to compile Nethack 3.6.6 and Dgamelaunch, and to configure them to serve game sessions via telnet.
This guide details how to set up a Nethack 3.6.6 server on CentOS 7 or 8. If you are using a different distribution, the required packages may have different names, and the commands used to install them will differ depending on your package manager.

The steps to setup a Nethack 3.6.6 server are as follows:

  1. Installing Requisite Packages
  2. Configuring Nethack for the Chroot Environment
  3. Compiling Nethack
  4. Compiling Dgamelaunch
  5. Creating the Chroot
  6. Configuring Dgamelaunch
  7. Testing Nethack and Dgamelaunch
  8. Setting up the Telnet Server

Here are the directories we will be using in this example:

  • Nethack will be configured before compiling in /home/nethack-temp/
  • The chroot location will be /home/nethack/
  • Dgamelaunch will be compiled into /home/dgamelaunch/

Installing Requisite Packages

The commands that you will run to install all required packages:

yum install gzip make gcc ncurses-libs ncurses-devel byacc flex autoconf automake git sqlite sqlite-devel xinetd telnet-server
dnf config-manager --set-enabled powertools #If CentOS8
yum install flex-devel

Required packages for compiling nethack:

yum install gzip make gcc ncurses-libs ncurses-devel byacc flex

Required packages for compiling dgamelaunch:

yum install git autoconf automake sqlite sqlite-devel
dnf config-manager --set-enabled powertools #If CentOS8
yum install flex-devel

Required packages for the telnet server:

yum install xinetd telnet-server

Downloading Nethack

Download the tarball and unpack it.

mkdir /home/nethack-temp/ && cd /home/nethack-temp/

wget http://nethack.org/download/3.6.6/nethack-366-src.tgz

tar -xzf nethack-366-src.tgz

cd NetHack-NetHack-3.6.6_Released

Configuring Nethack for the Chroot Environment

  1. Edit src/cmd.c

    2. Change function enter_explore_mode() so users cannot do that; comment it out. Here's what that function will look like when commented out:

    enter_explore_mode(VOID_ARGS)
{
/*    if (wizard) {
*        You("are in debug mode.");
*    } else if (discover) {
*        You("are already in explore mode.");
*    } else {
*#ifdef SYSCF
*#if defined(UNIX)
*        if (!sysopt.explorers || !sysopt.explorers[0]
*            || !check_user_string(sysopt.explorers)) {
*            You("cannot access explore mode.");
*            return 0;
*        }
*#endif
*#endif
*        pline(
*        "Beware!  From explore mode there will be no return to normal game.");
*        if (paranoid_query(ParanoidQuit,
*                           "Do you want to enter explore mode?")) {
*            clear_nhwindow(WIN_MESSAGE);
*            You("are now in non-scoring explore mode.");
*            discover = TRUE;
*        } else {
*            clear_nhwindow(WIN_MESSAGE);
*            pline("Resuming normal game.");
*        }
*    }
*/    return 0;
}

  2. Edit sys/unix/hints/linux

    3. PREFIX=/ #PREFIX=$(wildcard ~)/nh/install HACKDIR=$(PREFIX)/nh366 #SHELLDIR = $(PREFIX)/games

Compiling Nethack

  1. Run the setup script and `make all`.

    2. cd sys/unix/ sh setup.sh hints/linux cd ../.. make all make install

    This will (unfortunately) install nethack under /
    When I tried to install nethack using a different prefix, I couldn't get it to run after it had been moved into the chroot. So, we will be moving the compiled nethack into the chroot manually.

  2. Execute nethack and make sure it works.

    3. /nh366/nethack

Compiling Dgamelaunch

  1. Download the latest version from GitHub

    2. mkdir /home/dgamelaunch/ && cd /home/dgamelaunch/ git clone https://github.com/paxed/dgamelaunch.git

  2. Run autogen.sh, making sure to use an etc/dgamelaunch.conf file location within the chroot directory you'll be using.

    3. cd dgamelaunch ./autogen.sh --enable-sqlite --enable-shmem --with-config-file=/home/nethack/etc/dgamelaunch.conf

  3. Compile it.

    4. make

Creating the Chroot

  1. Edit these lines in dgl-create-chroot, as follows:

    2. CHROOT="/home/nethack/"
    NHSUBDIR="/nh366/"
    NH_VAR_PLAYGROUND="/nh366/var/"
    NH_PLAYGROUND_FIXED="/home/nethack-compiled/nh366"

    Also in dgl-create-chroot, change all references to "343" to "366". Here they are:

    mkdir -p "$CHROOT/dgldir/inprogress-nh343"

chown "$USRGRP" "$CHROOT/dgldir/inprogress-nh343"

cp "$CURDIR/dgl-default-rcfile" "dgl-default-rcfile.nh343"

chmod go+r dgl_menu_main_anon.txt dgl_menu_main_user.txt dgl-banner dgl-default-rcfile.nh343

  2. Setup the Chroot

    3. ./dgl-create-chroot

    Move /nh366 into /home/nethack/

    mv /home/nethack/nh366/var/ /home/nethack/
    mv -f /nh366 /home/nethack/
    chown -R games:games nh366/
    rm /games/nethack

Configuring Dgamelaunch

Edit these lines in /home/nethack/etc/dgamelaunch.conf as follows:

chroot_path (enter full chroot path) "/home/nethack/" #The backslash at the end matters
maxusers (set the maximum number of registered users, not simultaneous users)
SERVERID (your server name)
shed_uid (UID of user "games")
shed_gid (GID of group "games")
menu_max_idle_time (uncomment)

Also in dgamelaunch.conf, change all references to "343" to "366". Here they are:

commands["o"] = ifnxcp "/dgl-default-rcfile.nh343" "%ruserdata/%n/%n.nh343rc",

exec "/bin/virus" "%ruserdata/%n/%n.nh343rc"

commands["p"] = play_game "NH343"

game_path = "/nh343/nethack"

short_name = "NH343"

game_args = "/nh343/nethack", "-u", "%n"

rc_template = "/dgl-default-rcfile.nh343"

rc_fmt = "%ruserdata/%n/%n.nh343rc"

inprogressdir = "%rinprogress-nh343/"

commands = cp "/nh343/var/save/%u%n.gz" "/nh343/var/save/%u%n.gz.bak",

setenv "NETHACKOPTIONS" "@%ruserdata/%n/%n.nh343rc",

Testing Nethack and Dgamelaunch

  1. Make sure that you can run nethack inside the chroot environment.

    2. Try the following as root:

    cd /home/nethack/ chroot ./ nh366/nethack

    If you get an error like this...

    # cd /home/nethack/ # chroot ./ nh366/nethack nh366/nethack: error while loading shared libraries: libncurses.so.6: cannot open shared object file: No such file or directory

    ..then manually copy the file into the chroot directory, and try running nethack again

    # cp -v /lib64/libncurses.so.6 /home/nethack/lib64/ '/lib64/libncurses.so.6' -> '/home/nethack/lib64/libncurses.so.6'

  2. Make sure that dgamelaunch works.

    3. cd /home/nethack/ ./dgamelaunch

    If you do not get any output when running dgamelaunch, something is wrong.

Setting up the Telnet Server

  1. Install the required packages if you have not already.

    2. yum install xinetd telnet-server

  2. Set up the telnetd to accept incoming connections

    3. If you're using xinetd like we are in this example, you can put this in /etc/xinetd.d/dgl:

    service telnet
{
socket_type     = stream
protocol        = tcp
user            = root
wait            = no
server          = /usr/sbin/in.telnetd
server_args     = -h -L /home/nethack/dgamelaunch
rlimit_cpu      = 120
}

  3. Start the telnet server

    4. service xinetd start chkconfig xinetd on

Testing the Telnet Server

Try connecting locally using 'telnet 127.0.0.1'.
If you get an immediate "connection closed by foreign host", then something is probably wrong with dgamelaunch. A common issue is that the dgamelaunch config file was not specified correctly, and dgamelaunch is looking for it in /etc/dgamelaunch.conf and not in the chroot.

Customizing the Dgamelaunch Menus

  • Edit dgl-banner
  • Edit dgl_menu_*

In particular, change the menu option in dgl_menu_main_user.txt from "Play NetHack 3.4.3" to 3.6.6.

Cleaning Up

/home/nethack-temp/ can be removed if you don't need it.

External Links and References Used to Compile This Guide