85 lines
3.8 KiB
Markdown
Executable File
85 lines
3.8 KiB
Markdown
Executable File
- By default, access is denied.
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- Traffic destined for anywhere but to a select few services (i.e., TCP
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or UDP ports) is blocked by the local firewall.
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- NTP
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- IMAP(S)
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- POP(S)
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- OpenVPN
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- IPsec
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- HTTP(S) traffic caught by firewall, redirected to the mesh node's
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client IP and port.
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- **iptables -t nat -A PREROUTING -i wlan0 -p tcp --dport 80 -j
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REDIRECT --to-port 31337**
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- **iptables -t nat -A PREROUTING -i wlan0 -p tcp --dport 443 -j
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REDIRECT --to-port 31338**
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- We'd have to add an extra bit in there **--destination 10.x.x.1**
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- A web server listening on the redirect ports (31337/TCP and 31338/TCP)
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uses URI rewriting to point everything to a special URI:
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` <VirtualHost *:31337>`
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` RewriteEngine On`
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` RewriteRule .* `[`https://byzantium.mesh/`](https://byzantium.mesh/)` [R,L]`
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` `</VirtualHost>
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` `
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` <VirtualHost *:31338>`
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` RewriteEngine On`
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` RewriteRule .* `[`https://byzantium.mesh/`](https://byzantium.mesh/)` [R,L]`
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` `</VirtualHost>
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- The web server listening on ports 31337/TCP and 31338/TCP serves a
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page to the client. The client reads the text ("This is a wireless
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mesh, stuff about OPSEC, click here to pass through to the directory
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of services.") and clicks a button.
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- It'd be nice if the page also optionally displayed a message "There
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is a gateway to the public Net, so you can browse outside of this
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mesh." if a gateway route existed and had been propagated.
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- When the button is clicked the firewall is updated to permit that MAC
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address to send traffic.
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- **[ipset](http://ipset.netfilter.org/) -A capo_sessions_ipset
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CLIENT_IP,CLIENT_MAC**
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- Yes, MAC spoofing to bypass this is trivial. This isn't to prevent
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people from getting online if they don't have a valid room number,
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it's to force them to see a message from the admin and then kick
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them over to a directory of services curated by the node's software.
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- Set a timeout on the client IP? 10 minutes? 60 minutes? 5 minutes
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(same as DHCP lease time)?
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- **ipset -D capo_sessinos_ipset CLIENT_IP**
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- Captive::Portal includes a script (capo-ctl.pl) which already does
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this. In fact, you're supposed to run it from cron every ten minutes
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or so to clean out idle sessions.
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- Captive::Portal requires iptables (have it), ipset (need to compile
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and install it), and a rule in */etc/sudoers* so it can run without
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privileges but still carry out privileged tasks.
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- fping is used to test idle sessions (have it).
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- A CGI script that implements a captive portal is included in
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Captive::Portal, it's called capo.cgi and runs under Apache.
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- Basics of coding with this module:
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` my $capo = Captive::Portal->new(cfg_file=>$cfg_file);`
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` while (my $eq = CGI::Fast->new){`
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` $capo->run($q);`
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` }`
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- capo-ctl.pl is included with the module and manipulates the currently
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running IPtables rules (as well as backing store of Captive::Portal)
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with the ipset utility
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- Everything Captive::Portal relies on the same configuration file (by
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default, config.pl).
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- mock-server.pl is a script that pulls the HTML from a URI (say, a web
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server listening on wlan0) and spits it to stdout for testing.
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- Used for testing your setup without needing a client.
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- test-server.pl implements a very simple HTTP server so you can test
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your capi.cgi script without having to configure Apache.
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<!-- -->
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- We might have to modify capo.cgi to use the DBI Perl module to access
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the SQLite databases that hold the directories of services users can
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reach.
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- We may have either modify or subclass the Captive::Portal class and
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add support for extracting and using the IP address of the client
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interface (wlan0:1) rather than just the physical interface (wlan0).
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It's been a long time since I've done OO under Perl but it's certainly
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possible.
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- config.pl should be configured for no authentication (i.e., just a
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click-through). |