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Puzzling SMTP SolusVM
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Puzzling SMTP SolusVM

Ok, so this problem was reported to me about 8 hours ago and I can't seem to find the cause of it.

when I run $ nc -4 -t mail.anyhost.com 25 I've been getting 220 smtp.passthru on both client VMs and on the host, I've verified there is no rules in iptables, Dacentec has done some voodoo magic and said that they could verify it was sending on their end. I'm out of ideas. Does anyone else have any?

Comments

  • jarjar Patron Provider, Top Host, Veteran
    edited October 2015

    Dacentec intercepts traffic over port 25. Try to nmap (-Pn) a down IP address and notice port 25 shows open.

  • I could of sworn not even two months ago I was messing with telnet and able to connect over port 25... Maybe I'm thinking of a different datacenter...

  • jarjar Patron Provider, Top Host, Veteran
    edited October 2015

    @VPSSoldiers said:
    I could of sworn not even two months ago I was messing with telnet and able to connect over port 25... Maybe I'm thinking of a different datacenter...

    Yeah I was using a server there to test whether other servers were reachable. After a few days I noticed that no matter how much the other servers appeared to be down, I could always see 25 up and telnet to it. I think they run a content filtering relay locally.

  • VPSSoldiers said: I could of sworn not even two months ago I was messing with telnet and able to connect over port 25...

    If you have a cPanel server outside there, just relay off it on port 26, there is more than one way to skin this cat

  • Jar said: I think they run a content filtering relay locally.

    The answer I got from them before they did their voodoo.

    We use an SMTP firewall that prevents blacklisted IP addresses from sending mail.

    This filter sometimes interferes with normal SMTP operation. If you are having problems with the firewall you can try using proxy.dacentec.com as a smarthost.

    Thanked by 1jar
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