It's the exact same as Keygen-1, but a little different. Let's just connect to the given port and see what does it want?
```
$ nc defcon.org.in 8083
Send me 10 keys for getting a match separated by \n, followed by a NULL/EOF character.
```
No executable is given for this challenge, and it's given that it's related to Keygen-1. So, we just send the key obtained in previous challenge, repeated 10 times, separated by \n.
```
$ echo "5976657559745958655976555564937857597575\n5976657559745958655976555564937857597575\n5976657559745958655976555564937857597575\n5976657559745958655976555564937857597575\n5976657559745958655976555564937857597575\n5976657559745958655976555564937857597575\n5976657559745958655976555564937857597575\n5976657559745958655976555564937857597575\n5976657559745958655976555564937857597575\n5976657559745958655976555564937857597575" | nc defcon.org.in 8083

Flag: d4rk{r0ck1ng_keyg3n_123}c0de
```