Hotspot Server and NoCatAuth

This is the quick-and-dirty guide to getting a wireless gateway running with
the NoCatAuth system. If you simply want to “run a NoCat node”, this should
get you going.

For detailed instructions on how to set up your own Authentication Service
(and a good overall view of how this whole thing works), check out
Introduction.txt and AuthService.txt in the doc/ directory.

We don’t recommend running the gateway and the authservice on the same machine,
but if you’re dead-set on doing it, be sure to read doc/SameMachine.txt *first*.

## Installing a Gateway

For the terminally impatient

Check your prerequisites as below. Then, try the following:

$ su –
# tar zvxf NoCatAuth-x.xx.tar.gz
# cd NoCatAuth-x.xx
# make gateway
# cd /usr/local/nocat
# vi nocat.conf
# bin/gateway

If you see something to the effect of:

[2001-12-28 20:38:27] Resetting firewall.
[2001-12-28 20:38:27] Binding listener socket to

…then you’re up! Watch the progress in ‘nocat.log’, and give it a try.

Step by step

Currently, the gateway is designed to run on a standalone box. If you
have other firewall rules defined, THEY WILL BE OVERWRITTEN by the gateway
process when it starts. See the end of this file for how to get around
this, but please first consider running the gateway on its own machine.

Also, remember that running a gateway requires root permissions.

1. Make sure you have the prerequisites installed:

* Linux 2.4.x with iptables. You’ll find a sample kernel configuration
in etc/linux-2.4.config. Support for other OSes is planned,
especially FreeBSD. Support for ipchains is beta, and is currently
broken. Patches welcome.

* gpgv, a PGP signature verifier. gpgv comes with the gnupg package,
which can be downloaded from

* You’ll probably also want to run dhcpd on this machine, but DHCP
can in some cases be served from your access point or elsewhere on
your local network.

* If you want to try the bandwidth throttling rules, you’ll also need a
copy of the ‘tc’ tool from the iproute2 package. Get it at

* Optionally (and recommended), a local caching DNS server.

2. Unpack the NoCatAuth tarball. You probably already did this if you’re
reading this file.

$ tar zvxf NoCatAuth-x.xx.tar.gz

3. Edit the Makefile, if necessary. The only real option at present is
INST_PATH, which determines where NoCatAuth gets installed to. The default
is ‘/usr/local/nocat’, so if that’s okay with you, you can skip this step.

4. From the NoCatAuth directory, run ‘make gateway’. This will install the
important pieces of the gateway software.

5. Edit the /usr/local/nocat/nocat.conf file to suit. These parameters are

* InternalDevice must be set to the interface name of your wireless card,
or the ethernet card that talks to your AP (e.g., eth0. See
docs/Introduction.txt for more details.)

* ExternalDevice must be set to the name of the network interface
that talks to the Internet. (probably the ethernet card connected to
your DSL or cable modem, or your dialup device: eth1, ppp0, etc.)

* LocalNetwork needs to be set to the network address and mask of your
internal (wireless) network. This typically takes the form
111.222.333.444/, or, etc.

* DNSAddr needs to be set to the same domain name server address that
your DHCP server hands out, if and only if you’re using a DNS
outside your LocalNetwork (as specified above). Otherwise, if you’re
using a caching DNS server on the gateway or anywhere else on your
wireless network, leave this option commented out.

* GatewayMode toggles between Open and Captive mode. An Open gateway
just displays the html file specified in SplashForm for acceptance.
Captive mode implements the whole authentication process. If you
want people to have to login, use Captive mode.

* AuthServiceAddr, AuthServiceURL, and LogoutURL depend on your chosen
auth service (assuming you’re using Captive as your GatewayMode.)
Check with your local auth service admins for these values (or leave
the defaults to use our auth service.)

* IncludePorts and ExcludePorts can be set to restrict ports that public
users can access (say, to disallow email traffic.) If you use
IncludePorts, only the ports listed will be allowed. Using
ExcludePorts makes all ports available *except* the ports listed.
Currently, only TCP ports are supported.

## Starting the gateway

You should now be able to start the portal by running bin/gateway as root.
You’ll see a message to the effect of:

[2001-12-28 20:38:27] Resetting firewall.
[2001-12-28 20:38:27] Binding listener socket to

If it doesn’t start cleanly, read on.

The portal needs to know where to find (a) its perl libraries, and (b) its
nocat.conf configuration file. NoCatAuth tries very hard to figure out these
values on its own. If you installed to /usr/local/nocat, you should have no

Otherwise, you *may* need to add the following variables to the
shell environment before running the gateway script:

$ export PERL5LIB=/path/to/nocat/lib:$PERL5LIB
$ export NOCAT=/path/to/nocat/nocat.conf

Utilities like iptables, modprobe, and gpgv need should be in your $PATH
somewhere (if they aren’t already). For example:

$ export PATH=$PATH:/sbin:/usr/sbin:/usr/local/sbin

Starting the gateway is then as simple as: (from a root prompt)

# /path/to/nocat/bin/gateway

NOTE: You MUST run the gateway program as root, in order for it to be able to
update the firewall rules as needed. Arguably, this is a bug. Patches welcome.

To start the gateway service automatically at boot time, check out the
etc/nocat.rc script. Install it by copying it to /etc/rc.d/init.d, and
either add a call to it in your rc.local, or symlink it to your runlevel,
like this:

# ln -s /etc/rc.d/init.d/nocat.rc /etc/rc.d/rc3.d/S99nocat

Congratulations. You’re now running a gateway.

## Important Notes for the Gateway

* Make sure that your dhcp server hands out the same DNS address listed in
nocat.conf (if you’re using external DNS). Otherwise, your wireless
clients won’t be able to resolve hostnames.

* We have designed this software to be run on very modest hardware (a 486/50
with 32MB ram should be plenty.) Please consider running the gateway on a
dedicated machine before simply installing it on your existing firewall.

IP security is a complicated enough already… NoCat adds to the
complexity by introducing dynamic firewall rules that are triggered by
completely anonymous users (via the wireless.) While no security system is
foolproof, risk can be minimized by isolating your wireless node from the
rest of your network.

Please read docs/Introduction.txt (and a good book on firewalls) for more

### Thanks for using NoCatAuth. GOOD LUCK! PATCHES WELCOME!


About ngengeh

Nama gw ndry

Posted on February 17, 2007, in Belajar, Linux. Bookmark the permalink. Leave a comment.

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