dns forwarder not working when target server restarts

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This topic contains 4 replies, has 0 voices, and was last updated by  matiasurbieta 8 years, 6 months ago.

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  • #42668

    Hi, i have set a vpn gateway (192.168.0.3) using vpnc (cisco client) in a linux box that has also running dnsmasq for resolving vpn’s hosts from my intranet.
    In the other hand, i have running ZS as my main router y default gateway (192.168.0.2) of the intranet which also has configured the target domain,in example vpndomain.com, as a forwarder thats point to the vpngateway and routing rules for forwarding request.
    Every thing works well in such a way i can resolve vpndomain from my intranet and also access hosts. For example, i can resolve the by invoking from intranet:

    dig host.vpndomain.com 

    The request goes to the ZS router, and the name resolution is forwarder to the vpn gateway where dnsmasq daemon forward to the vpn the request.
    The problem arises when the vpn gateway is rebooted and the dns forwarder at ZS stop working but the vpngateway does. For instance:

    dig host.vpndomain.com #doesn't work
    dig @192.168.0.3 host.vpndomain.com #it does!

    Thanks in advance

    #51140

    ppalias
    Member

    From which client are you querying the dns? What is the sequense of dns servers it uses?

    #51141

    Hi, thanks for the quick response. Each host in the intranet has as default gateway and nameserver a zeroshell router which(192.168.0.2). If t any resolution request matches with a registered forwarder, it forwards the dns requirement to my vpngateway (192.168.0.3). There, dnsmask forward the request thru vpn where it is finally resolved. The dnsmask uses vpn configuration that is automatically set by vpnc (cisco client.) For example an scenario can be:
    A hosts (192.168.0.111) request a dns resolution
    ZS router check if it matches with a forwarder
    The request is forwarded to the vpn gateway(192.168.0.3)
    It is finally resolved

    Regards

    #51142

    ppalias
    Member

    It sounds like a problem of sending interesting traffic for the vpn to come up so that the DNS gets resolved. It is for sure an unorthodox approach of resolving 😀

    #51143

    Hi Fulvio, i noticed that when i make a minor change to bind configuration using the web frontend, forwarders start working due to bind service is rebooted. May be there is a way to reboot bind remotelly using ssh when the forwarder is rebooted.
    Which is the command-line for rebooting bind?
    if a make a call remotely using ssh , will console frontend (that is shown when login) be a problem? and how can i disable it?
    regards

    #51144

    ppalias
    Member

    You can restart dns from command line with the command

    /etc/init.d/dns restart
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