user66568: Is there any tutorial for altcoin fork creation?
I've found only tutorials for the very old versions, and any for the current ones.

user19338: I created an Altcoin based on this article. https://medium.com/@jordan.baczuk/how-to-fork-bitcoin-c39139506443
The article mentions 13 steps but I changed only the message prefix.
$ git branch
* v0.17.1

$ git diff
+++ b/src/chainparams.cpp
+        pchMessageStart[0] = 0xf1;
+        pchMessageStart[1] = 0xb2;
+        pchMessageStart[2] = 0xb3;
+        pchMessageStart[3] = 0xd4;

I started 3 processes; two forked bitcoind and one original bitcoind. forkA tries to connect to both original and forkB bitcoind. 
# forkA
/home/zono/bitcoinA/src/bitcoind -server -listen -port=17591 -rpcuser=bitcoinrpc -rpcpassword=bitcoinrpcpass -rpcport=16591 -datadir=$HOME/regtest/A/ -connect=localhost:17592 -connect=localhost:17593 -regtest -pid=$HOME/regtest/A/.pid -daemon -debug -listenonion=0

# original
/home/zono/bitcoinB/src/bitcoind -server -listen -port=17592 -rpcuser=bitcoinrpc -rpcpassword=bitcoinrpcpass -rpcport=16592 -datadir=$HOME/regtest/B/ -regtest -pid=$HOME/regtest/B/.pid -daemon -debug -listenonion=0

# forkB
/home/zono/bitcoinC/src/bitcoind -server -listen -port=17593 -rpcuser=bitcoinrpc -rpcpassword=bitcoinrpcpass -rpcport=16593 -datadir=$HOME/regtest/C/ -regtest -pid=$HOME/regtest/C/.pid -daemon -debug -listenonion=0

As you can see, forkA is connecting to forkB (port=17593)
$ ./bitcoinA/src/bitcoin-cli -rpcuser=bitcoinrpc -rpcpassword=bitcoinrpcpass -rpcport=16591 -regtest getpeerinfo
[
  {
    "id": 2,
    "addr": "localhost:17593",
    "addrbind": "127.0.0.1:37256",
    "services": "000000000000040d",
  ...
  }
]

You can see that original bitcoind refused to connect from forkA. (INVALID MESSAGESTART)
# forkA
2019-02-14T14:52:33Z trying connection localhost:17592 lastseen=0.0hrs
2019-02-14T14:52:33Z Added connection peer=2685
2019-02-14T14:52:33Z sending version (102 bytes) peer=2685
2019-02-14T14:52:33Z send version message: version 70015, blocks=0, us=[::]:0, peer=2685
2019-02-14T14:52:33Z socket closed
2019-02-14T14:52:33Z disconnecting peer=2685
2019-02-14T14:52:33Z Cleared nodestate for peer=2685

# original
2019-02-14T14:52:33Z Added connection peer=2684
2019-02-14T14:52:33Z connection from 127.0.0.1:54808 accepted
2019-02-14T14:52:33Z PROCESSMESSAGE: INVALID MESSAGESTART version peer=2684
2019-02-14T14:52:33Z disconnecting peer=2684
2019-02-14T14:52:33Z Cleared nodestate for peer=2684

A generated block on forkA is propagated to only forkB. 
# generate 1 block on forkA
./bitcoinA/src/bitcoin-cli -rpcuser=bitcoinrpc -rpcpassword=bitcoinrpcpass -rpcport=16591 -regtest generate 1

# forkA. current block = 1
$ ./bitcoinA/src/bitcoin-cli -rpcuser=bitcoinrpc -rpcpassword=bitcoinrpcpass -rpcport=16591 -regtest getblockchaininfo
{
  "chain": "regtest",
  "blocks": 1,

# original. current block = 0
$ ./bitcoinA/src/bitcoin-cli -rpcuser=bitcoinrpc -rpcpassword=bitcoinrpcpass -rpcport=16592 -regtest getblockchaininfo
{
  "chain": "regtest",
  "blocks": 0,

# forkB. current block = 1
$ ./bitcoinA/src/bitcoin-cli -rpcuser=bitcoinrpc -rpcpassword=bitcoinrpcpass -rpcport=16593 -regtest getblockchaininfo
{
  "chain": "regtest",
  "blocks": 1,


66568: <p>Is there any tutorial for altcoin fork creation?
I've found only tutorials for the very old versions, and any for the current ones.</p>
 19338: <p>I created an Altcoin based on this article. <a href="https://medium.com/@jordan.baczuk/how-to-fork-bitcoin-c39139506443" rel="nofollow noreferrer">https://medium.com/@jordan.baczuk/how-to-fork-bitcoin-c39139506443</a></p>

<p>The article mentions 13 steps but I changed only the message prefix.</p>

<pre><code>$ git branch
* v0.17.1

$ git diff
+++ b/src/chainparams.cpp
+        pchMessageStart[0] = 0xf1;
+        pchMessageStart[1] = 0xb2;
+        pchMessageStart[2] = 0xb3;
+        pchMessageStart[3] = 0xd4;
</code></pre>

<p>I started 3 processes; two forked bitcoind and one original bitcoind. forkA tries to connect to both original and forkB bitcoind. </p>

<pre><code># forkA
/home/zono/bitcoinA/src/bitcoind -server -listen -port=17591 -rpcuser=bitcoinrpc -rpcpassword=bitcoinrpcpass -rpcport=16591 -datadir=$HOME/regtest/A/ -connect=localhost:17592 -connect=localhost:17593 -regtest -pid=$HOME/regtest/A/.pid -daemon -debug -listenonion=0

# original
/home/zono/bitcoinB/src/bitcoind -server -listen -port=17592 -rpcuser=bitcoinrpc -rpcpassword=bitcoinrpcpass -rpcport=16592 -datadir=$HOME/regtest/B/ -regtest -pid=$HOME/regtest/B/.pid -daemon -debug -listenonion=0

# forkB
/home/zono/bitcoinC/src/bitcoind -server -listen -port=17593 -rpcuser=bitcoinrpc -rpcpassword=bitcoinrpcpass -rpcport=16593 -datadir=$HOME/regtest/C/ -regtest -pid=$HOME/regtest/C/.pid -daemon -debug -listenonion=0
</code></pre>

<p>As you can see, forkA is connecting to forkB (port=17593)</p>

<pre><code>$ ./bitcoinA/src/bitcoin-cli -rpcuser=bitcoinrpc -rpcpassword=bitcoinrpcpass -rpcport=16591 -regtest getpeerinfo
[
  {
    "id": 2,
    "addr": "localhost:17593",
    "addrbind": "127.0.0.1:37256",
    "services": "000000000000040d",
  ...
  }
]
</code></pre>

<p>You can see that original bitcoind refused to connect from forkA. (INVALID MESSAGESTART)</p>

<pre><code># forkA
2019-02-14T14:52:33Z trying connection localhost:17592 lastseen=0.0hrs
2019-02-14T14:52:33Z Added connection peer=2685
2019-02-14T14:52:33Z sending version (102 bytes) peer=2685
2019-02-14T14:52:33Z send version message: version 70015, blocks=0, us=[::]:0, peer=2685
2019-02-14T14:52:33Z socket closed
2019-02-14T14:52:33Z disconnecting peer=2685
2019-02-14T14:52:33Z Cleared nodestate for peer=2685

# original
2019-02-14T14:52:33Z Added connection peer=2684
2019-02-14T14:52:33Z connection from 127.0.0.1:54808 accepted
2019-02-14T14:52:33Z PROCESSMESSAGE: INVALID MESSAGESTART version peer=2684
2019-02-14T14:52:33Z disconnecting peer=2684
2019-02-14T14:52:33Z Cleared nodestate for peer=2684
</code></pre>

<p>A generated block on forkA is propagated to only forkB. </p>

<pre><code># generate 1 block on forkA
./bitcoinA/src/bitcoin-cli -rpcuser=bitcoinrpc -rpcpassword=bitcoinrpcpass -rpcport=16591 -regtest generate 1

# forkA. current block = 1
$ ./bitcoinA/src/bitcoin-cli -rpcuser=bitcoinrpc -rpcpassword=bitcoinrpcpass -rpcport=16591 -regtest getblockchaininfo
{
  "chain": "regtest",
  "blocks": 1,

# original. current block = 0
$ ./bitcoinA/src/bitcoin-cli -rpcuser=bitcoinrpc -rpcpassword=bitcoinrpcpass -rpcport=16592 -regtest getblockchaininfo
{
  "chain": "regtest",
  "blocks": 0,

# forkB. current block = 1
$ ./bitcoinA/src/bitcoin-cli -rpcuser=bitcoinrpc -rpcpassword=bitcoinrpcpass -rpcport=16593 -regtest getblockchaininfo
{
  "chain": "regtest",
  "blocks": 1,
</code></pre>
