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Feb
14
comment Does it make sense to create a “private” host-only network or vSwitch for VM-only communication on a VMware vSphere host?
Am I correct in understanding that the VMs are doing the VLAN tagging in your scenario for the VM to VM traffic?
Oct
3
comment Openvpn, forward packets very slowly
When I'm troubleshooting vpn issues like this, I basically get 4 packet captures (after checking that CPU isn't bound up anywhere): 1) client inside, 2) client outside, 3) server inside, 4) server outside. On the client side, if you are pushing all traffic through the tunnel, then capture all the traffic. On the server side, filter to just that client's internal and external IPs, but don't filter any further.
Oct
3
comment Openvpn, forward packets very slowly
Can you upload the tcpdump files in binary tcpdump format? This will make it easier to analyze in a tool such as wireshark (which makes this sort of debugging MUCH easier). Also, can you please tcpdump both the internal and external sides of the connection (simultaneously, if possible)? I.e. if you have packets to compare from tun0 and from eno1, it should be a piece of cake to figure out what is wrong.
Sep
30
comment Openvpn, forward packets very slowly
Can you add cpu information from the client and server while the traffic is being transferred?
Sep
30
comment Multiples ip address on interface. I want to specify one of them for output
Apparently I misread it. I thought you were saying the opposite (which was reinforced by Karma's comment). I'll edit the answer appropriately.
Sep
29
comment Multiples ip address on interface. I want to specify one of them for output
I'm not saying there is a typo, I'm saying that it is doing EXACTLY what it is configured to do: use source IP of 212.83.129.104 when routing via the default route. If the question is "why is my traffic sourced from 212.83.129.104 instead of 88.190.15.135?", then the answer is "because it is configured that way, and your provider has a static route to send it back to you via 88.190.15.135". If you don't want it to do that, then change the configuration so it doesn't source from that IP.
Sep
29
comment Multiples ip address on interface. I want to specify one of them for output
I don't see how the above implies they are doing funky stuff with routing. It seems to me that the provider simply has a route that says "212.83.129.104 goes to 88.190.15.135", so they route traffic to that IP via the 88.190.15.0/24 network. If he sources his packets from 212.83.129.104, as it is configured to do, then they will come back to him just fine, no tricks or funny business.
Jul
22
comment Allocated Memory difference in xen guests with Linux 2.6.18 and 2.6.32
On question 1, in the section below where you have the text "despite showing", you then go on to show that dmesg is reporting "500984k/524288k". That means "500984k is available out of 524288k total". The free command also shows 524288k total mem, as per your output.
Jul
22
comment Allocated Memory difference in xen guests with Linux 2.6.18 and 2.6.32
Centos 6.3 is also RedHat based, so will be different from Debian based (Ubuntu). Additionally, Centos 6.3 probably has different defaults compiled into the kernel than either 5.7 or Ubuntu, so it makes sense that it is different.
Jul
22
comment Why does OS X spend one more packet to establish and close a TCP connection?
tcpdump is perfectly valid for looking at this. The information is not easier to access in wireshark if you have to 1) install a GUI, 2) install wireshark.
Jul
22
comment Why VM cannot get the public IP I have from provider?
How about an ifconfig -a on the VM?
Jul
20
comment Reviewing firewall rules
RedSeal is more than just firewall rules, they do all kinds of stuff to help visualize your network security architecture, including determining if your current access control stance (implemented via firewalls, ACLs, etc.) is complaint with your desired company "policy" (or other standards, such as PCI-DSS, et al). As far as firewall rules go, they can analyze for a bunch of Best Practice checks, in addition to some firewall specific stuff such as unused rules, missing logging, etc. for a variety of different vendors.
Jun
11
comment How to restore Ubuntu server on a VMWare image after disk failure?
You probably need to mount specific partitions: "/dev/sdb3" or similar. Try "sudo fdisk -l /dev/sdb" to see what might be available.
Jun
10
comment How to restore Ubuntu server on a VMWare image after disk failure?
If you really have to "recover" it, i.e. make the actual same image bootable again, then yea, probably run the rescue process. Otherwise, just copy off your configs and data and you are all set (I've found that this tends to get much more reliable and consistent results, and I don't end up spending hours troubleshooting weird boot parameters and grub issues that I don't really understand.)
Jun
10
comment How does server handle multiple clients on the same port? Multiple sockets or multiple ports?
I second the recommendation for TCP/IP Illustrated.
May
28
comment How to connect the virtual networks of vmware guests running on different hosts?
Do the VMs all need to communicate with each other? Or just the host(s)?
May
28
comment How to connect the virtual networks of vmware guests running on different hosts?
Do the VMs all need to be on the same broadcast domain (i.e. subnet)?
May
26
comment GRE tunneling in vmware vsphere guest
The answer to this question is "Yes". But a one word answer is too short for a real answer, so I'm suggesting that you elaborate on your question with details on why you think it might not work and what your actual question is.
May
24
comment XenServer - Does the Hypervisor act as a router?
You could also create other vSwitches that aren't connected to a physical nic at all, to prevent broadcast or other traffic from being sent on the wire, although that clearly isn't the default configuration.
May
24
comment XenServer - Does the Hypervisor act as a router?
The default behavior is to create a virtual switch for each physical NIC in the system, and connect VMs to the first vSwitch that is created. If the VMs are just communicating with each other, and are on the same subnet, then the traffic won't leave this vSwitch (e.g. you could have the physical NIC disconnected and it would still work).