Ddos Threat

If you haven't done so already, you would need to file a complaint on him via the console in order for the enforcement team to investigate him. Calling out other gamers is not allowed on the forums.

Report them and block them via their profile.

i suggest reporting the player to xbox for threats of DDOS

Reporting a Player

Please also do not be name and shame. To report a player you will need to follow these steps.

• Press the Guide button and select Friends.
• Scroll right to Players, then select the user.
• From a game lobby: Select the user.
• Select View Profile.
• Select File Complaint.
• Review the information here and when you’re ready, select File Complaint again.
  
• Select one of the following reasons for filing the complaint: Text Message, Voice Message ,Voice Chat In-Game Voice , or others that may apply to the issue.
  

Also more information on the xbox report system can be found HERE.

To Mute and Block a Player / Avoid

To mute a player

1. Press the Guide button on your controller.
2. Select Friends, then go to the Players tab. Select the player’s gamertag.
3. Select Mute.
4. To block communications with a player
5. From the Xbox Dashboard, open a message from the player, and then select Block Communications. The player will not be able to send you any messages unless you send them one first.
   

To avoid a player

• Press the Guide button.
• Select Friends, then go to the Players tab. Select the player’s gamertag.
• Select Submit Player Review.
• Select Avoid This Player
• Select why you want to avoid the player: Communication, Game Behavior, or Player Skill.
  
• Select the specific reason why you want to avoid the player.

DOS or a DDoS Attack

Denial of service (DoS) or Distributed Denial of Service (DDoS) attacks

If you play games on Xbox LIVE, you could experience a denial of service (or DoS) attack or a distributed denial of service (or DDoS) attack. Such attacks may render your device (that is, your Xbox 360 console or your computer) temporarily unable to connect
to the Internet or to Xbox LIVE.

If you have an Xbox LIVE account, your Xbox 360 console could experience a DoS attack or DDoS attack from another Xbox LIVE account. DoS attacks and DDoS attacks are sometimes used as retaliation between Xbox LIVE gameplayers.

If you think you’ve experienced a DoS or DDoS attack, we recommend that you reset your Internet router and contact your Internet Service Provider (ISP). If you know who initiated the DoS or DDoS attack, you may also want to submit a player review to Xbox
LIVE and avoid the attacker in the future.

More info on these DOS and DDOS attack can be found
HERE.

Sounds like he provided his Console ID and the gtag of the "hacker". If this is your console ID, you really should get hacked because only someone that dumb would put their actual console ID on a public forum.

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I think you should check with Xbox Support Section of the forums or contact a moderator; he/she will tell you where to go. I suggest fyerball72.