Update 15_1_i2p_service.md

Author: shannona

15_1_i2p_service.md

@@ -1,32 +1,63 @@
 # 15.1: Bitcoin Core as an I2P (Invisible Internet Project) service
 
-Users should consider different trade-offs involved in using i2p with other networks in Bitcoin Core for better privacy:
+> :information_source: **NOTE:** This section has been recently added to the course and is an early draft that may still be awaiting review. Caveat reader.
 
-- Sybil Attacks and Network Partitioning is possible with `onlynet=i2p`
-- Running Onion service with i2p service is experimental for now.
+Rather than using the proxy-based Tor service to ensure the privacy of your Bitcoin communications, you may instead wish to use i2p, which is designed to act as a private network within the internet, rather than simply offering private acecss to internet services.
+
+## Understand the Differences
+
+Tor and i2p both offer private access to online services, but with different routing and databases, and with different architectures for relays. Since hidden services (such as Bitcoin access) are core to the design of i2p, they have also been better optimized:
+
+|  | Tor | i2p |
+| :---         |     :---:      |          ---: |
+| Routing   | [Onion](https://www.onion-router.net/)     | [Garlic](https://geti2p.net/en/docs/how/garlic-routing)    |
+| Network Database     | Trusted [Directory Servers](https://blog.torproject.org/possible-upcoming-attempts-disable-tor-network)       | [Distributed network database](https://geti2p.net/en/docs/how/network-database)      |
+| Relay     | **Two-way** encrypted connections between each Relay       | **One-way** connections between every server in its tunnels      |
+| Hidden services     | Slow       | Fast      |
+
+A more detailed comparison may be found at [geti2p.net](https://geti2p.net/en/comparison/tor).
+
+### Understand Tradeoffs for Limiting Outgoing Connections
+
+There are [tradeoffs](https://bitcoin.stackexchange.com/questions/107060/tor-and-i2p-tradeoffs-in-bitcoin-core) if you choose to support only i2p, only Tor, or both. These configurations, which limit outgoing clearnet connections, are made in Bitcoin Core using the `onlynet` argument in your `bitcoin.conf`.
+
+* `onlynet=onion`, which limits outgoing connections to Tor, can expose a node to Sybil attacks and can create network partitioning, because of limited connections between Tornet and the clearnet.
+* `onlynet=onion` and `onlynet=i2p` in conjunction, which runs Onion service with i2p service is experimental for now.
+
+## Install i2p
+
+To install i2p, you should make sure your ports are correctly set up and then you can continue with your setup process.
+
+### Prepare Ports
+
+To use i2p, you will need to open the following ports, which are required by i2p:
+
+1. **Outbound (Internet facing):** a random port between 9000 and 31000 is selected. It is best if all these ports are open for outbound connections, which doesn't affect your security. 
+- You can check firewall status using `sudo ufw status verbose`, which shouldn't deny outgoing connections by default.
+2. Inbound (Internet facing): optional. A variety of inbound ports are listed in the [i2p docs](https://geti2p.net/en/faq#ports).
 - For maximum privacy, it is preferable to disable accepting incoming connections.
 
-Read more: https://bitcoin.stackexchange.com/questions/107060/tor-and-i2p-tradeoffs-in-bitcoin-core
+### Run i2p
 
-Follow the below steps to run Bitcoin Core i2p service:
+The following will run Bitcoin Core i2p services:
 
-1. You can install `i2pd` on Ubuntu with below commands:
+1. Install `i2pd` on Ubuntu:
 
    ```
    sudo add-apt-repository ppa:purplei2p/i2pd
    sudo apt-get update
    sudo apt-get install i2pd
    ```
 
-   For installing on other OS: https://i2pd.readthedocs.io/en/latest/user-guide/install/
+   For installing on other OSes, see [these docs](https://i2pd.readthedocs.io/en/latest/user-guide/install/)
 
-2. Then [run](https://i2pd.readthedocs.io/en/latest/user-guide/run/) it and check if its running:
+2. [Run](https://i2pd.readthedocs.io/en/latest/user-guide/run/) the i2p service:
 
    ```
    $ sudo systemctl start i2pd.service
    ```
 
-   You should see it running on port 7656:
+3. Check that i2p is running. You should see it on port 7656:
 
    ```
    $ ss -nlt
@@ -36,29 +67,32 @@ Follow the below steps to run Bitcoin Core i2p service:
    LISTEN  0        4096           127.0.0.1:7656           0.0.0.0:*
    ```
 
-3. Add the following lines in `bitcoin.conf`. Config logging option `debug=i2p` is used to have additional information in the debug log about your I2P configuration and connections (Default location on Linux: ~/.bitcoin/bitcoin.conf):
+4. Add the following lines in `bitcoin.conf`: 
 
    ```
    i2psam=127.0.0.1:7656
    debug=i2p
    ```
+   The logging option, `debug=i2p`, is used to record additional information in the debug log about your i2p configuration and connections. The default location for this debugging file on Linux is: `~/.bitcoin/bitcoin.conf`:
 
 5. Restart `bitcoind`
 
    ```
    $ bitcoind
    ```
 
-6. Check `debug.log`if i2p was setup correctly or any errors printed in logs.  I2P address is mentioned in the logs and ends with _b32.i2p_:
+6. Check `debug.log` to see if i2p was setup correctly, or if any errors appeared in the logs.  
    ```
    2021-06-15T20:36:16Z i2paccept thread start
    2021-06-15T20:36:16Z I2P: Creating SAM session with 127.0.0.1:7656
 
    2021-06-15T20:36:56Z I2P: SAM session created: session id=3e0f35228b, my address=bmwyyuzyqdc5dcx27s4baltbu6zw7rbqfl2nmclt45i7ng3ul4pa.b32.i2p:18333
    2021-06-15T20:36:56Z AddLocal(bmwyyuzyqdc5dcx27s4baltbu6zw7rbqfl2nmclt45i7ng3ul4pa.b32.i2p:18333,4)
    ```
+   
+   The i2p address is mentioned in the logs, ending with _b32.i2p_. For example `bmwyyuzyqdc5dcx27s4baltbu6zw7rbqfl2nmclt45i7ng3ul4pa.b32.i2p:18333`.
 
-7. Confirm `i2p_private_key` was created in Bitcoin Core data directory. The first time Bitcoin Core connects to the I2P router, its I2P address (and corresponding private key) will be automatically generated and saved in a file named *i2p_private_key*:
+7. Confirm `i2p_private_key` was created in the Bitcoin Core data directory. The first time Bitcoin Core connects to the i2p router, its i2p address (and corresponding private key) will be automatically generated and saved in a file named *i2p_private_key*:
    ```
    ~/.bitcoin/testnet3$ ls
 
@@ -67,18 +101,20 @@ Follow the below steps to run Bitcoin Core i2p service:
    blocks       fee_estimates.dat  peers.dat
    ```
 
-8. `bitcoin-cli -netinfo` or `bitcoin-cli getnetworkinfo`returns i2p address:
+8. Check that `bitcoin-cli -netinfo` or `bitcoin-cli getnetworkinfo`returns the i2p address:
 
    ```
    Local addresses
    bmwyyuzyqdc5dcx27s4baltbu6zw7rbqfl2nmclt45i7ng3ul4pa.b32.i2p     port  18333    score      4
    ```
+  
+You now have your Bitcoin server accessible through the i2p network at your new local address.
 
 ## Summary: Bitcoin Core as an I2P (Invisible Internet Project) service
 
-It is always good to have alternatives for privacy and not depend only on Tor to run Bitcoin Core as hidden service. Since i2p was recently added in Bitcoin Core, not many people use it. Experiment with it and report bugs if you find any issues.
+It is always good to have alternatives for privacy and not depend solely on Tor for running Bitcoin Core as a hidden service. Since i2p was recently added in Bitcoin Core, not many people use it. Experiment with it and report bugs if you find any issues.
 
-> :information_source: **NOTE:** For the official i2prouter implementation in Java, visit [download](https://geti2p.net/en/download) page and follow the instructions for your Operating System. Once installed, open a terminal window and type `i2prouter start`. Then visit `127.0.0.1:7657` in your browser to enable SAM. To do so, select: "Configure Homepage", then "Clients", and finally select the "Play Button" next to SAM application Bridge. On the left side of the page, there should be a green light next to "Shared Clients".
+> :information_source: **NOTE:** For the official i2prouter implementation in Java, visit the [i2p download page](https://geti2p.net/en/download) and follow the instructions for your Operating System. Once installed, open a terminal window and type `i2prouter start`. Then visit `127.0.0.1:7657` in your browser to enable SAM. To do so, select: "Configure Homepage", then "Clients", and finally select the "Play Button" next to SAM application Bridge. On the left side of the page, there should be a green light next to "Shared Clients".
 
 Move on to "Programming with RPC" with [Chapter Sixteen: Talking to Bitcoind with C](16_0_Talking_to_Bitcoind.md).