ISPConfig Perfect Server - Open DNS Resolver

Discussion in 'General' started by crypter, Feb 10, 2014.

  1. crypter

    crypter New Member

    Hey guys,

    I followed this guide (Perfect Server CentOS 6.4 | Apache) exactly, no more and no less. However I just got an email from my host saying that they have detected my server is acting as an open resolver. They asked that I update my DNS server to not be an open resolver.

    My questions are, how did this happen if I followed the guide exactly? Also how exactly do I fix this?

    Any help would be greatly appreciated. Thank you!
  2. srijan

    srijan New Member HowtoForge Supporter

    Hi Crypter,

    ISPconfig comes with its own Antivirus capability. Open resolver remains safe from external attack& spoofings from the antivirus clamav. I think that there could be issues with the clamav service.

    Please check the clamav service status.
    /etc/init.d/clamd.amavisd status

    Case1:If it is not running then please start the service.
    /etc/init.d/clamd.amavisd start

    Case2:If it is not present then please install the service.
    then just download the ispconfig 3 tar.gz again, unpack it and run the update.php in the install folder. Choose to reconfigure services during update.

  3. till

    till Super Moderator Staff Member ISPConfig Developer

    Please check that your named.conf looks exactly as described in the guide in chapter 17:

    // named.conf
    // Provided by Red Hat bind package to configure the ISC BIND named(8) DNS
    // server as a caching only nameserver (as a localhost DNS resolver only).
    // See /usr/share/doc/bind*/sample/ for example named configuration files.
    options {
            listen-on port 53 { any; };
            listen-on-v6 port 53 { any; };
            directory       "/var/named";
            dump-file       "/var/named/data/cache_dump.db";
            statistics-file "/var/named/data/named_stats.txt";
            memstatistics-file "/var/named/data/named_mem_stats.txt";
            allow-query     { any; };
            recursion no;
            allow-recursion { none; };
    logging {
            channel default_debug {
                    file "data/";
                    severity dynamic;
    zone "." IN {
            type hint;
            file "";
    include "/etc/named.conf.local";
    important are these two lines:

    recursion no;
    allow-recursion { none; };
  4. Clouseau

    Clouseau Member

    Last edited: Dec 27, 2014
  5. till

    till Super Moderator Staff Member ISPConfig Developer

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