Unable to access internet when firewall on

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This topic contains 9 replies, has 2 voices, and was last updated by  yathindra 7 years ago.

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  • #5329

    yathindra
    Participant

    Hi,
    This post is not related to this site but asking since i need some help related to this problem. Actually my problem is when my firewall is on i am unable to access the internet. Actual problem according to my firewall reports IE(inernet explorer) sends data through one port but it is getting reply on some other port hence firewall is blocking the internet. In general when application send data through one port it will get reply on the same port. But here it is different where the problem might be? please give reply for this if any body knows otherwise suggest me where can i get solution for this or provide some site where i can get help related to this. Actually i use broaband router to access the internet. Generally this case is not occuring for all cases only for few i am facing this problem. OS is windows XP just for information. Please give reply as soon as possible. I am not getting reply in some other forums hence posted here.

    Thanking you,

    Regards,
    Yathindra.

    #6946

    Vadim Smirnov
    Moderator

    Something similar is possible if you use IE to download from FTP server:

    FTP protocol normally uses two connections, first is control channel for FTP commands and second data channel to send the actual data. In active mode FTP client creates a local listening socket and sends PORT command to FTP server specifying local IP address and port. Then FTP server connects this IP:port and requested file is transferred over this TCP connection. Thus request for file is sent over one TCP connection but file is sent over another one. In passive mode both control and data channels are initiated by FTP client (this mode is easier for NAT traversal), but once again request is sent by client over control channel but data are sent from server over data channel. This is very similar to what you have reported. If I remember fine normally IE uses FTP in passive mode.

    #6947

    yathindra
    Participant

    Hi,

    Thanks for your response. But for normal browsing any browser uses HTTP protocol instead of FTP in that case where might the problem will be?

    #6948

    Vadim Smirnov
    Moderator

    HTTP is more straightforward and should not behave like that.

    #6949

    yathindra
    Participant

    Hi,

    Then where might the problem will be? I need some help regarding this suggestions needed regarding this issue. I am having this problem from so many days.

    #6950

    Vadim Smirnov
    Moderator

    Difficult to say as this issue needs a deep analyses. May be this is just a software bug in firewall.

    #6951

    yathindra
    Participant

    Hi,
    How to rectify this. As you said deep analysis can you say in which things i need to look in to for analysis to identify the problem. Also as you said software bug in firewall where it might be? any idea?

    Thanking you,

    Regards,
    Yathindra.

    #6952

    Vadim Smirnov
    Moderator

    I’m not aware much about you firewall code, but I would start with loging data out of your firewall solkution and running network sniffer in parallel in order to catch the situation and analyze what hapens.

    #6953

    yathindra
    Participant

    Hi,

    Thanks for your suggestion.

    #6954

    yathindra
    Participant

    Hi,

    I downloaded EtherDetect packet sniffer tool to trace for packet flow. While installing it it also installs WinPCap tool also. Now i have both winpkfilter and winpCap network drivers. When i run the sniffer tool and then access the internet i am unable to access the internet. When i not capture i am able to access the internet. What could be the problem. Is there any compatability issue with both drivers or what else? Please reply. Otherwise suggest a packet sniffer tool which is compatible with winpkfilter also and able to work when try to capture packets with the sniffer tool. Waiting for reply.

    Thanking you,

    Regards,
    Yathindra.

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