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rDNS, how? (feddit.dk)
submitted 2 years ago by to c/selfhosted@lemmy.world
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I'm on at least 2 blocklists at this point for the crime of not having reverse DNS set up. I don't know how rDNS works. No amount of reading Wikipedia is helping me understand what I have to do.

  • I have a domain at a registrar which gives me bog standard DNS.
  • I have Apache running on my network.
  • I have PiHole running on my network.

My understanding is that rDNS is not set up at my registrar, but somewhere in my network. What do I do?

Thank you for your time.

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[–] 1 point 2 years ago (1 child)

Your ISP may block 80 / 443. Try moving your webserver to an alternate high port and ask the users to test with that.

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  • [–] [S] 1 point 2 years ago (1 child)

    But it's only very few people. If my ISP blocks these ports, why 99% of people have no issues?

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  • [–] 1 point 2 years ago (1 child)

    At this point I'd install wireshark and see if I'm getting their TCP connections at all.

    Given your other routing issues though, I would guess you have another config issue on your firewall.

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  • [–] [S] 1 point 2 years ago* (last edited 2 years ago) 
      5.186.33.87 > 89.150.135.135: ICMP echo request, id 1, seq 43476, length 40
12:38:19.843890 d0:50:99:81:48:17 > 4c:6d:58:4a:97:d4, ethertype IPv4 (0x0800), length 74: (tos 0x0, ttl 64, id 21715, offset 0, flags [none], proto ICMP (1), length 60, bad cksum 0 (->1dc0)!)
    89.150.135.135 > 5.186.33.87: ICMP echo reply, id 1, seq 43476, length 40
12:38:20.219177 d0:50:99:81:48:17 > 4c:6d:58:4a:97:d4, ethertype IPv4 (0x0800), length 43: (tos 0x0, ttl 64, id 32958, offset 0, flags [none], proto ICMP (1), length 29, bad cksum 0 (->3f6d)!)

    Packet capture from the router for 4 pings from him to me. 2 of 8 packets expected were captured and have bad checksums. Disregard, all 8 expected packets do show up

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