First commit

2022-02-06 16:47:35 +01:00
commit 6864ed7938
5 changed files with 107 additions and 0 deletions
--- a/README.md
+++ b/README.md
@@ -0,0 +1,107 @@
+# FTTH Tiscali without modem
+
+This is a short guide on how to connect your Linux box to the Internet using directly the GPON provided by Tiscali.
+
+## TL;DR
+
+You just need `pppd` and a virtual Ethernet device. The latter is created with:
+
+`ip link add link eth0 name eth0.835 type vlan id 835`
+
+assuming your ethernet device is `eth0`.
+
+Credentials for PPPoE can  be obtained [here for Tiscali](https://assistenza.tiscali.it/supporto/moduli/servizi/modem-libero/). You can also sniff the [CHAP](https://en.wikipedia.org/wiki/Challenge-Handshake_Authentication_Protocol) authentication and crack it, the password is just 6 numeric characters.
+
+To connect to the PPPoE server, install `pppd` and configure it
+
+##### /etc/ppp/peers/tiscali
+
+```
+plugin pppoe.so
+# rp_pppoe_ac 'your ac name'
+# rp_pppoe_service 'your service name'
+
+# network interface
+eth0.835
+# login name
+name "NAME.SURNAME@tiscali.it"
+usepeerdns
+persist
+# Uncomment this if you want to enable dial on demand
+#demand
+#idle 180
+defaultroute
+hide-password
+noauth
+```
+
+and
+
+##### /etc/ppp/chap-secrets
+
+```
+# Secrets for authentication using CHAP
+# client        server  secret                  IP addresses
+"NAME.SURNAME@tiscali.it"       *       "123456"
+```
+
+(replace 123456 with your password)
+
+Finally you can switch on the service like:
+
+```
+ppp call tiscali
+```
+
+you can use `journalctl -f` and check whether things are going fine.
+
+Systemd automatization can be created with the help of [these scripts](https://gitlab.com/jimdigriz/debian-clearfog-gt-8k/-/blob/master/README.md).
+
+## Long Story
+
+The FFTH service comes with a **GPON** ([gigabit-capable passive optical network](https://en.wikipedia.org/wiki/G.984)), and I wanted to connect the PC with my self hosted services directly to its ethernet port, bypassing the big black box (ZTE H388X a.k.a. ZTE Modem Tim Hub+) customized with some mysterious proprietary firmware from TISCALI (I asked, of course they don't share it).
+
+Needless to say, using the credentials that TISCALI gave me directly with `pppd` on my ethernet interface did not work. The logs and the error messages are
+
+```
+pppd[1336]: Plugin pppoe.so loaded.
+pppd[1336]: PPPoE plugin from pppd 2.4.9
+pppd[1337]: pppd 2.4.9 started by pie, uid 0
+kernel: NET: Registered PF_PPPOX protocol family
+pppd[1337]: Timeout waiting for PADO packets
+pppd[1337]: Unable to complete PPPoE Discovery
+```
+
+
+
+For some reason, nobody replied with an *Offer* (PADO) to my request for a PPP *Initiation* (PADI). Not much gained from the error message, so the only way to find how to talk to the PPPoE server is to collect a working setup.
+
+I managed to sniff the traffic between the modem and the GPON with this fantastic Ethernet Hub from the 90s!
+
+![HUB](README.assets/hub1.jpeg)
+
+The approach is [like this](https://wiki.wireshark.org/CaptureSetup/Ethernet#capture-using-an-ethernet-hub):
+
+![](README.assets/Capture-switch-hub-ws.png)
+
+
+
+The packets captured just after switching on the ZTE H388X are shown here:
+
+![packets](README.assets/packets.png)
+
+There are basically three steps:
+
+* Red box: a termination request. Probably to clean up everything before starting a new session.
+* Yellow box: the PPP Initialization starts from the ZTE and is followed by an Offer from the Cisco server.
+* Green box: the authentication, with CHAP protocol.
+
+When using `pppd` the first packet is a PADI, which looks exactly the same as the one in No. 7 above, except for the 802.1Q part shown by the blue arrow. That was indeed the trick: the server replies only is the PADI request comes from a VLAN with ID:835.
+
+Setting the PPP device to a newly created vlan with
+
+```
+`ip link add link eth0 name eth0.835 type vlan id 835`
+```
+
+makes the Cisco server happy and it promptly replies to our PADI packet.