Unable to reach server on port 53

psytanium

• May 24, 2019 10:21

Hello, Recently i had a problem with Godaddy when all user where blocked and unable to reach my server on port 53 when using UDP protocol. After few hours the problem was fixed and all users where able to connect again. But 1 user is still unable to reach the server. This is the 3rd day, he tried another ISP, it worked for few hours and down again. It is working only when he use VPN. He tried to telnet my ip on port 25: 220-We do not authorize the use of this system to transport unsolicited, 220 and/ or bulk email. I tried to whitelist his ip in cPhulk and allow it on iptables firewall. All packets timeout when he ping my server ip. Any idea how can we identify where is the problem coming from ? Thanks

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  cPanelLauren

  • May 24, 2019 16:29

  He tried to telnet my ip on port 25: 220-We do not authorize the use of this system to transport unsolicited, 220 and/ or bulk email.

  
  This shows he was able to connect. If you've tried whitelisting him locally and ruled out the firewall you may need to check with your provider to determine if they've got him blocked on their network. You'd be able to determine where the failure occurs by having him run a traceroute locally most likely.

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  psytanium

  • May 25, 2019 18:30

  Hi, Yes i whitelisted his IPs in cPhulk, and added them to "Quick Allow" in "ConfigServer Security & Firewall". He traced rout the server IP, the result is the attached image. Regards,

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  cPanelLauren

  • May 28, 2019 16:00

  He times out at what looks to be a private IP from what I can see in the screenshot after hitting your provider's network. If you're NAT routed it could be a block on the appliance in front of the server but ultimately this isn't something we're able to troubleshoot, you'll need to work with your provider to resolve this.

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