How does a computer create a 'Response' packet? - Infosec.Pub
  • "Initials" by "Florian Körner", licensed under "CC0 1.0". / Remix of the original. - Created with dicebear.comInitialsFlorian Körnerhttps://github.com/dicebear/dicebearDR
    driftWood
    Now 100%

    I added more comments on the original post which describes the situation a bit more.

    Don't know what's a good way to get the comments linked to this post.

    Do take a look if you are interested.

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  • How does a computer create a 'Response' packet? - Infosec.Pub
  • "Initials" by "Florian Körner", licensed under "CC0 1.0". / Remix of the original. - Created with dicebear.comInitialsFlorian Körnerhttps://github.com/dicebear/dicebearDR
    driftWood
    Now 100%

    Standards are set of rules. But still different vendors implement them separately. For e.g. TCP/IP stack implementation is a bit different in Windows and Linux but end user generally never realises this because it's close enough that things still work. I want to know what is the sequence of events when Linux creates a Response packet for a ping Request it received.

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  • How does a computer create a 'Response' packet?
  • "Initials" by "Florian Körner", licensed under "CC0 1.0". / Remix of the original. - Created with dicebear.comInitialsFlorian Körnerhttps://github.com/dicebear/dicebearDR
    driftWood
    Now 100%

    I recently tested this using wireshark. When I run packet capture on nic1 of dstPC I see ping request packets coming, but no response packets leaving the interface. On nic2 I don't see any packets leaving either. So kind of stumped what is happening. It seems the computer just drops the response packet and it never makes it till any nic. But still don't have a good explanation of WHY the packet gets dropped.

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  • How does a computer create a 'Response' packet?
  • "Initials" by "Florian Körner", licensed under "CC0 1.0". / Remix of the original. - Created with dicebear.comInitialsFlorian Körnerhttps://github.com/dicebear/dicebearDR
    driftWood
    Now 100%

    OK this is what I was thinking too. So consider this scenario:

    srcPCnic1 - 192.168.1.100/24 DG: 192.168.1.1 dstPCnic1 - 192.168.2.100/24 dstPCnic2 - 192.168.1.101/24 DG: 192.168.1.1

    Topology: srcPCnic1 -> RTR -> dstPCnic1 Assume srcPCnic1 is also connected to dstPCnic2 via a switch. (Sorry if its difficult to imagine with the crude description)

    On srcPC execute: ping 192.168.2.100 RTR will route the packet to dstPC. dstPC receives the packet on nic1. dstPC sends the Response packet via nic2.

    Is the above understanding correct?

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  • https://infosec.pub/post/15458682

    Reposting here since want to know how a Linux computer handles this scenario.

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    Consider a Ping Request packet arriving on a computer with 2 NICs (multi-homed PC). The packet is received on 1 of the interfaces. Now the computer has to send the Ping Response packet. To fill the source IP and source MAC address the computer does which of the following? - Computer first determines which interface should be used as the egress interface by looking at the Destination IP address. Destination IP address was taken from source IP address field of Ping Request packet. Once it determines egress port, it will enter that interface's IP and MAC address in the Ping Response packet. - Computer takes the destination IP and MAC address of the Ping Request packet and just flips them over to fill source IP and MAC address in Ping Response packet.

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    Suggestions for cheap enterprise grade hardware to run linux headless.
  • "Initials" by "Florian Körner", licensed under "CC0 1.0". / Remix of the original. - Created with dicebear.comInitialsFlorian Körnerhttps://github.com/dicebear/dicebearDR
    driftWood
    Now 100%

    Not really. Just has to run till at least 5years at least. Since this will be deployed at customer site, pine64 and android both are not feasible. Thanks for the suggestion though.

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  • Suggestions for cheap enterprise grade hardware to run linux headless.
  • "Initials" by "Florian Körner", licensed under "CC0 1.0". / Remix of the original. - Created with dicebear.comInitialsFlorian Körnerhttps://github.com/dicebear/dicebearDR
    driftWood
    Now 100%

    I have one in the lab at office. Were abt to be thrown out. Nursed it back to life somehow. Good to play around plus company foots the electricity bill so win-win.

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  • Suggestions for cheap enterprise grade hardware to run linux headless.
  • "Initials" by "Florian Körner", licensed under "CC0 1.0". / Remix of the original. - Created with dicebear.comInitialsFlorian Körnerhttps://github.com/dicebear/dicebearDR
    driftWood
    Now 100%

    I know. I felt while writing the post that this feels wrong writing those words in same sentence. The scenario is that we would deploy the hardware on customer premises so it has to be supported and very reliable(hence enterprise grade). But i personally think that all enterprise grade hardware is way overkill for running ansible playbooks. So was trying to see if there is an intersection point between these opposite requirements.

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  • Suggestions for cheap enterprise grade hardware to run linux headless.
  • "Initials" by "Florian Körner", licensed under "CC0 1.0". / Remix of the original. - Created with dicebear.comInitialsFlorian Körnerhttps://github.com/dicebear/dicebearDR
    driftWood
    Now 100%

    So this will be deployed for customer sites. I dont think they will be happy with second hand stuff from ebay 😀 For my personal stuff i would have been happy with that though.

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  • Suggestions for cheap enterprise grade hardware to run linux headless.
  • "Initials" by "Florian Körner", licensed under "CC0 1.0". / Remix of the original. - Created with dicebear.comInitialsFlorian Körnerhttps://github.com/dicebear/dicebearDR
    driftWood
    Now 100%

    Budget is not an issue actually. This is going to be deployed for customers but i want to it to be as cheap aspossible to get them maximum value for their money. Software stack is going to be minimal. Probably alpine linux or ubuntu server. Spec wise i think even an i3 level cpu is fine. Ram 8gb, hard disk 256 gb ssd should be more than enough. Dont require any fancy wireless stuff like wifi and Bluetooth.

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  • Basically what it says in the title. I did a lot of searching in Internet. I think small form factor computers are mt best bet. But I still feel they are costly for my purpose. I am going to be running some ansible playbooks periodically on the machine. SBCs i looked at either had very high specs for this use case and thus higher price or they had other fratures i dont want like - wifi, graphics card etc. I am preferring enterprise hardware because this would eventually be used in business where people will not settle for anything less.

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    *Permanently Deleted*
  • "Initials" by "Florian Körner", licensed under "CC0 1.0". / Remix of the original. - Created with dicebear.comInitialsFlorian Körnerhttps://github.com/dicebear/dicebearDR
    driftWood
    Now 88%

    One of the KDE devs sharing why it is 'Mega Release' from their perspective. Quite interesting to hear about all the things that go on in the background in software development. https://tube.kockatoo.org/videos/watch/e6e8f177-22f1-432a-9c7f-ab76b17a5b54

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  • XCP-NG with XOSTOR working?
  • "Initials" by "Florian Körner", licensed under "CC0 1.0". / Remix of the original. - Created with dicebear.comInitialsFlorian Körnerhttps://github.com/dicebear/dicebearDR
    driftWood
    Now 100%

    Figured it out. I had created 3 VMs but was trying to created shared storage between 2 xcp-ng instances. I assumed that this can be done and the 3 instance will only act as witness without contributing to the storage.

    After going through many replies on the forum thread I understood that you need minimum 3 hosts participating in the storage. Modified my setup to match the requirements (was easy since they are just VMs) all the instructions worked correctly.

    The error about missing linstor python module was that I hadn't installed necessary packages on 3rd host in the pool since I assumed it doesn't require XOSTOR instructions to be run on it since it would not be participating in shared storage. This is my understanding though and I can be wrong.

    Having written above I think I can still have only 2 hosts participating in storage but just need to install necessary packages on third host also. Will try and see how it goes.

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  • I have started trying out xcp-ng as an alternative to VMWare solutions for virtualization. Currently I have setup 3 VMs of xcp-ng v8.2.1. I have also setup Xen Orxhestra build from source. I wanted to try out XOSTOR solution for shared storage. I have followed instructions mentioned in the forum: https://xcp-ng.org/forum/topic/5361/xostor-hyperconvergence-preview I am getting errors at the storage creation step which is step 4 in the forum post I linked. The error I get is "Missing python module 'linstor'." Anyone has got xcp-ng working with XOSTOR here?

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    "Initials" by "Florian Körner", licensed under "CC0 1.0". / Remix of the original. - Created with dicebear.comInitialsFlorian Körnerhttps://github.com/dicebear/dicebearDR
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    driftWood

    driftWood@ infosec.pub