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dfdumont
Contributor
Contributor

Bizzare network behavior, Win 10, Wrkstn 15.5, bridged

I don't even know how to describe this.  Case in point, I bring up a naked, minimal CentOS 8.1 server from ISO.  Upon reboot after install I then wget two files from the same internet location.  One, a text file works.  The other a TGZ ball does not.  It just  hangs.  If I trace things out I can see that the machine actually gets the "200" message from the server, it just never initiates the transfer.

If I then do the normal "dnf (yum) -y update" which is typically step 2 of any install (or apt update) and the thing can't find any repositories.  Or it can, but it can't maintain a connection with them and they time out. 

Now for all of you who are going to say something like "The firewall in your environment.." take note of this.  I have a beefy laptop running Ubuntu which is configured to be KVM server.  I can bring up that same naked minimal CentOs 8.1 server from the same ISO file I used on Workstation, and it works just fine there.  No issues.  Blows through a 'dnf -y update' quickly.  Can download either file upon reboot after install. (Can you see now why I set this test up?) This isn't environmental.  These two machines are under the same environment.

It behaves like a misconfigured firewall.  So it COULD be something in the Win10 firewall, since the laptop running Ubuntu wouldn't suffer under that.  I just don't know where to even look.  At the moment I can't produce any viable instances in Workstation.  They are all bad, even old ones that used to work.  I can't even consistently SSH into old VMs.  It's got to be a network thing somewhere.

I don't even know what to post.  What do you want to help figure this out?  All ideas welcome.

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3 Replies
dfdumont
Contributor
Contributor

Here's something at least.  These are the PCAP from the two file downloads I mentioned above.  This is from an old server that used to work.  'tcpdump' isn't available on a naked, minimal install.

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Alex_Romeo
Leadership
Leadership

Hi,

I had a hard time understanding the problem.

I wanted to ask you if you can install vmware-tools and then check if it improves.

https://linuxconfig.org/how-to-install-vmware-tools-on-rhel-8-centos-8

https://linuxhint.com/install_vmware_tools_centos8_rhel8_vmware/

ARomeo

Blog: https://www.aleadmin.it/
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dariusd
VMware Employee
VMware Employee

Thanks for posting the capture.  When downloading the .tgz, the client has done everything correctly and it is waiting for the remote server to follow up with the HTTP content, but it never arrives.

From what I've seen so far, I suspect you have a Path MTU Discovery blackhole along the route between the path between your host and the server, and mixed MTUs.  It's basically a guess, but the symptoms broadly match.

If you slightly lower the guest's interface MTU (e.g. sudo ifconfig en### mtu 1400), do things start to work properly again?

--

Darius

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