2. Starting the deamon
3. Stopping the deamon
4. Portmapping Notes
5. Security Notes
First of all you will need the Intel Linux UPnP SDK which can be downloaded
from sourceforge here:
Untar the Intel UPnP SDK, but before you compile and install, you will need
to make one change for Windows Messenger to work properly. Under
the upnpsdk tree, the file src/ssdp/ssdplib.c, on line 406, the following
line needs to be changed from:
SelfAddr.sin_addr.s_addr = inet_addr(SSDP_IP);
SelfAddr.sin_addr.s_addr = htonl(INADDR_ANY);
Next download and untar the Linux IGD. Now just run "make" and "make install" in
the Linux IGD directory. This will copy the program files into /usr/bin/ and
the configuration files into /etc/linuxigd.
Also, you will need to make sure you have a route in your routing table for the
multicast address. The following line should work:
route add -net 22.214.171.124 netmask 255.0.0.0 int_if
Just replace int_if with the name of your internal interface
(i.e., route add -net 126.96.36.199 netmask 255.0.0.0 eth1)
NOTE: the file has /usr/sbin/iptables as the location of the iptables
executable. If yours is different, either add a symbolic link here for
it, or just change the references in gateway.h for the variable IPTABLES.
2. Starting the daemon
To run, type:
upnpd <extif> <intif>
Where <extif> and <intif> are the names of your external interface and internal
interface respectively. The daemon will fork into the background and begin
running. Debug messages go to /var/log/debug and Error messages go to
/var/log/messages. Upon successful start up, the last line you should see
in /var/log/debug is Advertisements Sent. This means the program is loaded
and the upnp service is initialized. Any other problems would most likely be
due to your existing firewall rules or routes. See the README included with this
distribution for more information on the details of running the daemon.
3. Stopping the daemon
To stop the upnpd process the easiest way is to run:
at a shell prompt. Also, it may be killed by doing:
where process_id is the inital process id of the program. However, since
there are many of them, it's usually just easiest to run killall. This
will cause all portmappings to be closed cleanly and advertisements to be
sent to clients telling them the daemon is no longer available.
4. Portmapping notes
NOTE: This program only creates DNAT (portmap) entries in you firewall on the
external interface (public ip). Any other firewall code must be set to allow
basically all tcp and udp through the FORWARD chain to your client machines,
and the client machines must be able to contact the firewall using tcp and udp
through the firewall's INPUT chain on it internal interface.
We will be adding some checks to see if FORWARD has a default policy of DROP or
REJECT, however placing rules once we determine this is a bit tricky.
At the moment there is no real way to check to see if a packet matching this rule will
pass through any additional rules that may be located above it. Also, we will
probably need to check for any rules below as well. Hopefully we can get this
In the meantime, please be aware of this fact, and if you are seeing
Advertisements sent in the /var/log/debug file (or whatever you have syslog
set to log DEBUG level messages to), but you are not seeing AddPortMaps,
your firewall configuration is most likely the problem, or it could be the following problem.
UPnP works with the 188.8.131.52/255.0.0.0 multicast addresses. Windows Messenger
may also send request to a Unicast address, and thus the reason for the patch
to the UPnP source code for this to work. Nevertheless, to add a route in
your box for the multicast address, just use the following command, replaceing
<int_if> with the interface name of your inside interface name (i.e., eth0).
route add -net 184.108.40.206 netmask 255.0.0.0 <int_if>
That's it, you'll want to make sure your iptables rules aren't blocking this as
well. Iptables has great strengths, but one of its weaknesses is no usespace
api at the moment to help with us intelligently adding rules. So most of
getting this to work requires you understanding how UPnP works, and being able
to adjust your firewall rules to this. The above should get you started,
however. It's rather simple.
5. Security notes
There are many opponents against UPnP.
However, we feel that Open Source is all about giving people choices, and
letting intelligent people make intelligent decisions about its use. A lot
of us really NEED this daemon, and can live with the consequences because we are
simply connecting a home network to the internet through one ip, and we
would have had the windows machines (or whatever internet device) connected
directly in the first place. That being said, here we go:
UPnP version 1.0, on which this program is based, is inherently flawed. As
with alot of Microsoft supported software, there was a lot of theory put out
there, but no code. What appears to have happened is that in Microsoft's first
UPnP implementation they weren't concerned with security or any advanced controls.
Simply all they wanted was connectivity. So we are stuck with this for now.
The UPnP server, by itself, does no security checking. If it recieves a UPnP
request to add a portmapping for some ip address inside the firewall, it just
does it. This program will attempt to verify the source ip contained in the
UPnP request against the source ip of the actual packet, but as always, these
can be forged. The UPnP server makes no attempt to verify this connection with
the caller, and therefore it just assumes that whoever asked is the person really
Theoretically this could open up ports on some other box than the caller to
the outside world, and this is where intelligent decision making comes in.
If you restrict the ability of this to happen with iptables rules, then this
becomes a non-issue, and only the machines that iptables allows to have stuff
go to will be allowed. But sure, everyone can come up with some way to get
around this so listen.
We are going to try to do the best we can to place source ip verification,
config files that say which machines can request portmappings, and which
machines can recieve portmappings, and any other things that come along.
This SOFTWARE IS AN BETA RELEASE AND NO CLAIMS ARE MADE TO ITS SECURITY OR
ITS FUNCTIONALITY. Just want to let you guys know that if you can think of
a way to screw the security up with this, we'd like to hear about it on the
mailing list. If you want to write in and tell us how totally off base we are
and how this is a useless, security plagued, Microsoft product driven piece
of software, let me just tell you what our mothers always say, "If you don't
have something nice to say, then don't say anything at all!". We appreciate
constructive criticism, but let's try to keep the flames to yourself.