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Thread: Weird things happening with a server

  1. #11
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    Re: Weird things happening with a server

    Quote Originally Posted by soamz View Post
    I have a server, which has 2 ports only.
    1 port is connected directly to the router to give it the public IP access.
    2nd port is connected to my access network switch, which has more than 100+ devices, which are on private IP, 7.7.7.xxx , 10.10.10.xxx , 10.10.11.xxx
    I agree completely with @volkswagner. I don't think you understand TCP/IP networking at all. In this instance you do not understand alias IP addressing of NIC interfaces. Here is the rule you have to follow
    After the primary interface IP address (e.g. eth0 ipaddr) all additional network IP address must be in same subnet. For example if your eth0 using 10.0.0.7 IP address then alias must be setup using a subnet in the same network range as determined by the subnet mask.
    You simply can't do this
    Code:
    7.7.7.xxx , 10.10.10.xxx , 10.10.11.xxx
    -BAB1

  2. #12
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    Re: Weird things happening with a server

    Quote Originally Posted by volkswagner View Post
    In my opinion, it's unreasonable to come to this or any forum (even paid support) and expect help after sound advise has been given, but ignored.

    If this were paid support for software, the simple response would be, "we don't support public ip ranges as private subnets".

    It's not like you asked for networking help, and got marital advise.

    Regardless of the fact that using 7.X.X.X address space MAY not be your problem, it's bad practice and MAY be causing this or other problems.
    Until this is fixed, I wouldn't offer any advise.

    Again, my opinions.
    Sir, we have removed 7.7.7.x now.
    Now only left is 10.10.11.xx and 10.10.10.xx

    Can you help suggest ?

    Quote Originally Posted by bab1 View Post
    I agree completely with @volkswagner. I don't think you understand TCP/IP networking at all. In this instance you do not understand alias IP addressing of NIC interfaces. Here is the rule you have to follow
    You simply can't do this
    Code:
    7.7.7.xxx , 10.10.10.xxx , 10.10.11.xxx
    bab, eth0 is the public IP.
    And eth1 is where the switch is connected which has all devices connected.
    It has devices like 10.10.11.xx and 10.10.10.xx

    And I read, we should add virtual interfaces for eth1 if we have multiple subnets using.

    What did I miss ?
    Last edited by howefield; May 11th, 2016 at 08:16 AM. Reason: posts combined.

  3. #13
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    Re: Weird things happening with a server

    Quote Originally Posted by soamz View Post
    bab, eth0 is the public IP.
    And eth1 is where the switch is connected which has all devices connected.
    It has devices like 10.10.11.xx and 10.10.10.xx

    And I read, we should add virtual interfaces for eth1 if we have multiple subnets using.

    What did I miss ?
    Everything. You should start with understanding the basic principles of IP addressing. There are thousands of pages on the Internet that provide information on this. Where did you read " we should add virtual interfaces for eth1 if we have multiple subnets using"?

    Regardless of what the NIC name is (eth0 or eth1 etc) you don't seem to understood what the point really is. That being; all alias IP addresses of any interface must be in the same subnet as the base IP address of that interface. These are alias IP addresses, not virtual; meaning they are alternatives to the base IP address of the interface.
    -BAB1

  4. #14
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    Re: Weird things happening with a server

    Quote Originally Posted by bab1 View Post
    Everything. You should start with understanding the basic principles of IP addressing. There are thousands of pages on the Internet that provide information on this. Where did you read " we should add virtual interfaces for eth1 if we have multiple subnets using"?

    Regardless of what the NIC name is (eth0 or eth1 etc) you don't seem to understood what the point really is. That being; all alias IP addresses of any interface must be in the same subnet as the base IP address of that interface. These are alias IP addresses, not virtual; meaning they are alternatives to the base IP address of the interface.
    http://askubuntu.com/questions/54920...-not-permanent

  5. #15
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    Re: Weird things happening with a server

    I'm not going to debate this with you. Read the literature.

    You have to be able to discuss what you are doing, rather than using an unrelated hyperlink as your entire reply.
    -BAB1

  6. #16
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    Re: Weird things happening with a server

    I'm not sure I agree with @bab1, I believe you can use alias interfaces for multiple subnets on same interface.
    You definitely don't want to have multiple gateways though. Multiple gateways are a whole different animal, which I have yet to tackle.

    I believe I've used virtual interfaces much like shown in the legacy model here.

    @soamz, please don't use screenshots to paste text results. Use the
    HTML Code:
    [code][/code]
    tags to wrap pasted text.

    You should be able to use virtual interfaces or have multiple ipAddreses/netmask configured inside one interface, which is also show in above link.

    The ping results shown on your earlier screen shot show pings to three hosts on same subnet, with two out of three not responding. This seems as it could
    easily be a remote host issue, firewall issue, or other. Since one host in the same subnet does respond, it seems your config is working.

    To update please post the following:

    Code:
    cat /etc/network/interfaces
    Code:
    route
    Code:
    iptables -L
    In my experience "weird" or unexpected/unpredictable networking results was almost always related to some firewall rule or typo in network config.

    Please also take the time to explain your environment/topology, hosts, switch(s), router, firewalls, etc. A network diagram may be helpful.
    Nothing is ever easy, but if it is difficult you must be doing it wrong.

  7. #17
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    Re: Weird things happening with a server

    Before I start typing the reply, Im looking for the THANK YOU BUTTON!!

    Where is it ??

    Quote Originally Posted by volkswagner View Post
    I'm not sure I agree with @bab1, I believe you can use alias interfaces for multiple subnets on same interface.
    You definitely don't want to have multiple gateways though. Multiple gateways are a whole different animal, which I have yet to tackle.

    I believe I've used virtual interfaces much like shown in the legacy model here.

    @soamz, please don't use screenshots to paste text results. Use the
    HTML Code:
    [code][/code]
    tags to wrap pasted text.

    You should be able to use virtual interfaces or have multiple ipAddreses/netmask configured inside one interface, which is also show in above link.

    The ping results shown on your earlier screen shot show pings to three hosts on same subnet, with two out of three not responding. This seems as it could
    easily be a remote host issue, firewall issue, or other. Since one host in the same subnet does respond, it seems your config is working.

    To update please post the following:

    Code:
    cat /etc/network/interfaces
    Code:
    route
    Code:
    iptables -L
    In my experience "weird" or unexpected/unpredictable networking results was almost always related to some firewall rule or typo in network config.

    Please also take the time to explain your environment/topology, hosts, switch(s), router, firewalls, etc. A network diagram may be helpful.


    Okay here are the output :

    HTML Code:
    jetnms@jetnms:~$ cat /etc/network/interfaces# This file describes the network interfaces available on your system# and how to activate them. For more information, see interfaces(5).
    # The loopback network interfaceauto lo eth0 eth1:1 eth1:2 eth1:3iface lo inet loopback
    # The primary network interfaceiface eth0 inet static        address 103.194.232.9        netmask 255.255.255.240        network 103.194.232.0        broadcast 103.194.232.15        gateway 103.194.232.1        # dns-* options are implemented by the resolvconf package, if installed        dns-nameservers 8.8.8.8jetnms@jetnms:~$
    jetnms@jetnms:~$ cat /etc/network/interfaces# This file describes the network interfaces available on your system# and how to activate them. For more information, see interfaces(5).
    # The loopback network interfaceauto lo eth0 eth1:1 eth1:2 eth1:3iface lo inet loopback
    # The primary network interfaceiface eth0 inet static        address 103.194.232.9        netmask 255.255.255.240        network 103.194.232.0        broadcast 103.194.232.15        gateway 103.194.232.1        # dns-* options are implemented by the resolvconf package, if installed        dns-nameservers 8.8.8.8jetnms@jetnms:~$
    HTML Code:
    
    jetnms@jetnms:~$ routeKernel IP routing tableDestination     Gateway         Genmask         Flags Metric Ref    Use Ifacedefault         103.194.232.1   0.0.0.0         UG    0      0        0 eth07.7.7.0         *               255.255.255.0   U     0      0        0 eth110.10.10.0      *               255.255.255.0   U     0      0        0 eth110.10.11.0      *               255.255.255.0   U     0      0        0 eth1localnet        *               255.255.255.240 U     0      0        0 eth0jetnms@jetnms:~$
    HTML Code:
    jetnms@jetnms:~$ iptables -Lmodprobe: ERROR: could not insert 'ip_tables': Operation not permittediptables v1.4.21: can't initialize iptables table `filter': Table does not exist (do you need to insmod?)Perhaps iptables or your kernel needs to be upgraded.
    Attached screenshot.
    Screenshot_8.png


    Screenshot_9.png

    The problem is,
    the devices ping from the server command line now, then stops after 5-10 mins, then again pings.

    I even monitor the ping every second, you can see how it comes and goes.
    Screenshot_12.png

    And there is absolutely no issue with the devices, or remote hosts.
    IM able to ping them all continuous without fail.

    But they play tricks within the server only, dont know whats really happening.
    Its ghost effect!!!!

    For example, if I have a device, and I have set it to static IP 10.10.11.27 / 255.255.255.0 subnet / 10.10.11.1 default gateway.

    It doesnt ping when I connect.
    While connected, I simply change the subnet to 255.0.0.0 or change gateway IP to 10.10.11.0 or something.
    Then immediately the ping starts working.

    Then again it stops after 5-10 mins, then again works, then if I refresh or change it to 255.255.255.0 , then again works, then again stops.
    It feels like, everytime the device gets restarted, ping works, then stops, vice versa.

    GHOST!!

    I have removed the entries from /etc/network/interfaces , still I see the data inside the ifconfig command.
    Dont know, where it got hard coded.

    Screenshot_13.png
    Last edited by howefield; May 11th, 2016 at 08:17 AM. Reason: posts combined.

  8. #18
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    Re: Weird things happening with a server

    @soamz, please read the FAQs and learn about proper posting.

    Perhaps my request to enter text in code tags was not easy to understand. I wrapped the request in html tags because
    it was the easiest way to display. As a beginner you should avoid using "post quick reply" and use "go advanced". This way
    you'll see the different tags to wrap you information. The code tags will properly format your text. As you can see in your html wrapped
    paste, the info is not easily readable (not properly formatted).

    I'll repeat, please don't use screenshots to post text based info. If you need a reason to follow this request I'll say this... For me, opening
    a screenshot is inconvenient, the text contents can't be copied an pasted into my own searches to easily help you, it's also not searchable/indexable
    by forum search or search engine bots. This means if someone has similar problem, config, or mis-config, it won't reference your post.
    Nothing is ever easy, but if it is difficult you must be doing it wrong.

  9. #19
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    Re: Weird things happening with a server

    Quote Originally Posted by soamz View Post
    I have removed the entries from /etc/network/interfaces , still I see the data inside the ifconfig command.
    Dont know, where it got hard coded.

    Screenshot_13.png
    Did you restart networking or reboot after making changes?

    Also you'll need to use sudo for your iptables command. I didn't write sudo, because your previous posts showed you were logged in as root.

    Code:
    sudo iptables -L
    Last edited by volkswagner; May 9th, 2016 at 12:41 AM.
    Nothing is ever easy, but if it is difficult you must be doing it wrong.

  10. #20
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    Re: Weird things happening with a server

    yes, I had restarted and even restarted the server 3-4 times.

    Here is the output of iptables -L

    Code:
    jetnms@jetnms:~$ sudo -i[sudo] password for jetnms: 
    root@jetnms:~# iptables -L
    Chain INPUT (policy ACCEPT)
    target     prot opt source               destination         
    
    
    Chain FORWARD (policy ACCEPT)
    target     prot opt source               destination         
    
    
    Chain OUTPUT (policy ACCEPT)
    target     prot opt source               destination         
    root@jetnms:~#

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