Port recognition withnmapor you can use recon

┌──(root@ghost)-[/home/ghost]
└─# recon meow.htb

    .o oOOOOOOOo                                            OOOo
    Ob.OOOOOOOo  OOOo.      oOOo.                      .adOOOOOOO
    OboO"""""""""""".OOo. .oOOOOOo.    OOOo.oOOOOOo.."""""""""'OO
    OOP.oOOOOOOOOOOO "POOOOOOOOOOOo.   `"OOOOOOOOOP,OOOOOOOOOOOB'
    `O'OOOO'     `OOOOo"OOOOOOOOOOO` .adOOOOOOOOO"oOOO'    `OOOOo
    .OOOO'            `OOOOOOOOOOOOOOOOOOOOOOOOOO'            `OO
    OOOOO                 '"OOOOOOOOOOOOOOOO"`                oOO
   oOOOOOba.                .adOOOOOOOOOOba               .adOOOOo.
  oOOOOOOOOOOOOOba.    .adOOOOOOOOOO@^OOOOOOOba.     .adOOOOOOOOOOOO
 OOOOOOOOOOOOOOOOO.OOOOOOOOOOOOOO"`  '"OOOOOOOOOOOOO.OOOOOOOOOOOOOO
 "OOOO"       "YOoOOOOMOIONODOO"`  .   '"OOROAOPOEOOOoOY"     "OOO"
    Y           'OOOOOOOOOOOOOO: .oOOo. :OOOOOOOOOOO?'         :`
    :            .oO%OOOOOOOOOOo.OOOOOO.oOOOOOOOOOOOO?         .
    .            oOOP"%OOOOOOOOoOOOOOOO?oOOOOO?OOOO"OOo
                 '%o  OOOO"%OOOO%"%OOOOO"OOOOOO"OOO':
                      `$"  `OOOO' `O"Y ' `OOOO'  o             .
    .                  .     OP"          : o     .
                              :
                              .

[R3C0N] by 0bfxgh0st 4 WWA with ❤
Let's do some rev engees turn on radare, can you read me that red thing? :P YoungerMaster

[OS] Linux (99%)
Starting Nmap 7.92 ( https://nmap.org ) at 2022-07-19 11:19 EDT
NSE: Loaded 1 scripts for scanning.
NSE: Script Pre-scanning.
Initiating NSE at 11:19
Completed NSE at 11:19, 0.00s elapsed
Initiating Ping Scan at 11:19
Scanning meow.htb (10.129.133.8) [4 ports]
Completed Ping Scan at 11:19, 0.07s elapsed (1 total hosts)
Initiating SYN Stealth Scan at 11:19
Scanning meow.htb (10.129.133.8) [65535 ports]
Discovered open port 23/tcp on 10.129.133.8
Completed SYN Stealth Scan at 11:20, 14.26s elapsed (65535 total ports)
NSE: Script scanning 10.129.133.8.
Initiating NSE at 11:20
Completed NSE at 11:20, 0.00s elapsed
Nmap scan report for meow.htb (10.129.133.8)
Host is up (0.078s latency).
Not shown: 65533 closed tcp ports (reset), 1 filtered tcp port (no-response)
Some closed ports may be reported as filtered due to --defeat-rst-ratelimit
PORT   STATE SERVICE
23/tcp open  telnet

NSE: Script Post-scanning.
Initiating NSE at 11:20
Completed NSE at 11:20, 0.00s elapsed
Read data files from: /usr/bin/../share/nmap
Nmap done: 1 IP address (1 host up) scanned in 14.60 seconds
           Raw packets sent: 70900 (3.120MB) | Rcvd: 70393 (2.816MB)

recon reports telnet service on port 23

┌──(root@ghost)-[/home/ghost]
└─# telnet meow.htb 23
Trying 10.129.133.8...
Connected to meow.htb.
Escape character is '^]'.

  █  █         ▐▌     ▄█▄ █          ▄▄▄▄
  █▄▄█ ▀▀█ █▀▀ ▐▌▄▀    █  █▀█ █▀█    █▌▄█ ▄▀▀▄ ▀▄▀
  █  █ █▄█ █▄▄ ▐█▀▄    █  █ █ █▄▄    █▌▄█ ▀▄▄▀ █▀█


Meow login: root
Welcome to Ubuntu 20.04.2 LTS (GNU/Linux 5.4.0-77-generic x86_64)

 * Documentation:  https://help.ubuntu.com
 * Management:     https://landscape.canonical.com
 * Support:        https://ubuntu.com/advantage

  System information as of Tue 19 Jul 2022 03:29:59 PM UTC

  System load:           0.0
  Usage of /:            41.7% of 7.75GB
  Memory usage:          4%
  Swap usage:            0%
  Processes:             138
  Users logged in:       0
  IPv4 address for eth0: 10.129.133.8
  IPv6 address for eth0: dead:beef::250:56ff:fe96:f506

 * Super-optimized for small spaces - read how we shrank the memory
   footprint of MicroK8s to make it the smallest full K8s around.

   https://ubuntu.com/blog/microk8s-memory-optimisation

75 updates can be applied immediately.
31 of these updates are standard security updates.
To see these additional updates run: apt list --upgradable


The list of available updates is more than a week old.
To check for new updates run: sudo apt update

Last login: Tue Jul 19 15:29:24 UTC 2022 on pts/0
root@Meow:~# cat flag.txt
b40abdfe23665f766f9c61ecba8a4c19