Rename OpenGGSN to OsmoGGSN
Osmocom has maintained this program since about 7 years now, while
the original author / copyright holder has completely disappeared.
With the introduction of Osmocom-style CTRL and VTY interfaces,
the way how the program is used and configured has substantially
changed. In order to avoid confusion in terms of configuration file
format etc, let's rename it to OsmoGGSN.
Change-Id: I2da30f7d4828e185bfac1a4e2d8414b01cbe4f9d
diff --git a/doc/osmo-ggsn.8 b/doc/osmo-ggsn.8
new file mode 100644
index 0000000..b9f928f
--- /dev/null
+++ b/doc/osmo-ggsn.8
@@ -0,0 +1,173 @@
+
+.\" * OsmoGGSN - Gateway GPRS Support Node
+.\" * Copyright (C) 2002, 2003 Mondru AB.
+.\" *
+.\" * The contents of this file may be used under the terms of the GNU
+.\" * General Public License Version 2, provided that the above copyright
+.\" * notice and this permission notice is included in all copies or
+.\" * substantial portions of the software.
+.\" *
+.\" * The initial developer of the original code is
+.\" * Jens Jakobsen <jj@openggsn.org>
+.\" *
+.\" * Contributor(s):
+.\" *
+.\" Manual page for osmo-ggsn
+.\" SH section heading
+.\" SS subsection heading
+.\" LP paragraph
+.\" IP indented paragraph
+.\" TP hanging label
+
+.TH osmo-ggsn 8 "August 2017"
+.SH NAME
+osmo-ggsn \- Gateway GPRS Support Node.
+.SH SYNOPSIS
+.B osmo-ggsn
+\-\-help
+
+.B osmo-ggsn
+\-\-version
+
+.B osmo-ggsn
+[
+.BI \-\-help
+] [
+.BI \-\-daemonize
+] [
+.BI \-\-config-file " file"
+] [
+.BI \-\-version
+]
+.SH DESCRIPTION
+.B osmo-ggsn
+is part of the
+.B OsmoGGSN
+project, and implements a Gateway GPRS Support Node. It is used by
+mobile operators as the interface between the Internet and the rest of
+the mobile network infrastructure.
+
+The GPRS functionality and protocols has been standardised by the
+Third Generation Partnership Project (3GPP). According to the 3GPP
+specifications a GGSN has two interfaces: The Gn/Gp interface and the
+Gi interface.
+
+The Gn/Gp interface can be seen as the downlink interface of the
+GGSN. It is used for communicating with the Serving GPRS Support Node
+(SGSN) which again interfaces to the radio access network. The Gn/Gp
+interface uses the GPRS tunneling protocol (GTP). User data packets
+(typically IP packets) are tunneled over GTP, which again uses UDP
+over IP.
+
+The other interface can be thought of as the uplink interface, and
+interfaces the GGSN to an external data network. Gi is most often an
+interface to the Internet.
+.B osmo-ggsn
+uses the
+.B TUN/TAP driver
+for the Gi interface. A tun network interface is established when the
+.B osmo-ggsn
+is started.
+
+.B osmo-ggsn
+will accept incoming connections from mobile stations through the
+radio access network and the SGSN. When a connection request is
+received the ggsn will allocate a dynamic IP address for the mobile
+station, and allow the mobile station to access the Gi
+interface. Connections are terminated by either the mobile station or
+the SGSN. Runtime errors are reported using the Osmocom logging
+framework.
+
+Typically
+.B osmo-ggsn
+will be deployed with two Ethernet interfaces. One for the Gn/Gp
+interface, and one for the Gi interface. Policy routing and firewall
+rules should be used in order to separate Gi traffic from Gn/Gp
+traffic.
+
+.SH OPTIONS
+.TP
+.BI --help
+Print help and exit.
+
+.TP
+.BI --version
+Print version and exit.
+
+.TP
+.BI --daemonize
+Run in background as a daemon (default = off)
+
+.TP
+.BI --config-file " file"
+Read configuration
+.I file
+(default = ./openggsn.cfg)
+
+.SH FILES
+.I ./osmo-ggsn.cfg
+.RS
+The configuration file for
+.B osmo-ggsn.
+.RE
+.I /var/run/osmo-ggsn.pid
+.RS
+Process ID file.
+.RE
+.I /var/lib/osmo-ggsn
+.RS
+Directory holding nonvolatile data.
+.RE
+
+.SH BUGS
+Report all bugs to the OsmoGGSN bug tracking list at
+.I https://osmocom.org/projects/openggsn
+
+.B osmo-ggsn
+has very limited management support. Currently both SNMP as well as
+billing mechanisms are missing.
+
+
+.SH "SEE ALSO"
+.BR sgsnemu (8)
+
+.SH NOTES
+.LP
+
+Besides the long options documented in this man page
+.B osmo-ggsn
+also accepts a number of short options with the same functionality. Use
+.B osmo-ggsn --help
+for a full list of all the available options.
+
+The TUN/TAP driver is required for proper operation of
+.B osmo-ggsn.
+For linux kernels later than 2.4.7 the TUN/TAP driver is included in the kernel, but typically needs to be loaded manually with
+.B modprobe tun.
+For automatic loading the line
+.B alias char-major-10-200 tun
+can be added to
+.B /etc/modules.conf.
+For other platforms see
+.I http://vtun.sourceforge.net/tun/
+for information on how to install and configure the tun driver.
+
+.B osmo-ggsn
+uses the GPRS Tunneling Protocol (GTP) as specified by the Third
+Generation Partnership Project (3GPP). 3GPP protocols specifications
+can be found at
+.I http://www.3gpp.org
+
+.SH COPYRIGHT
+
+Copyright (C) 2002, 2003 by Mondru AB.
+Copyright (C) 2017 Harald Welte
+
+The contents of this file may be used under the terms of the GNU
+General Public License Version 2, provided that the above copyright
+notice and this permission notice is included in all copies or
+substantial portions of the software.
+
+.SH AUTHORS
+Jens Jakobsen <jj@openggsn.org>
+Harald Welte <laforge@gnumonks.org>