networking – Discover IPMI IP address by scanning all possible direct LAN addresses

I have a Supermicro server board that powers on but wont post.

I have connected a LAN cable to the dedicated IPMI LAN port on the board and am trying to discover what the IPMI IP address of the board is.

I have tried scanning the local network via:

nmap -n -sP

However I as the server is not connected to anything other than a laptop via IPMI it does not know it’s on the local network, and I have seen SuperMicro IPMI addresses around 172.17.x.x.

I have not been able to find a list of all possible IPMI addresses to narrow down. How can I scan the entire 172.x.x.x address range using nmap? or any other ideas for finding this server via direct connection to an IPMI port.

networking – Drawbacks of having pruned and collapsed packets

I am a newbie in networking field, I come across a note that we should not have pruned packets and collapsed packets, if we have, we should have to optimize the system.

But the note (neither the internet) didn’t provide much context on why we shouldn’t have pruned and collapsed packets and what problems that it makes?

$ netstat -s | grep socket      
299 packets pruned from receive queue because of socket buffer overrun
2701 TCP sockets finished time wait in fast timer
5 delayed acks further delayed because of locked socket
92 packets collapsed in receive queue due to low socket buffer

Here, you can see I have 299 packets which were pruned and 92 packets were collapsed.

Is it bad? if yes, why? what issues I will face due to this?

networking – Multiplayer game server headerless (Unreal/Unity) vs Custom Maps

I’ve been pondering about different approaches that a multiplayer game server can be managed and programmed.

For instance some of the big engines like UE4 & Unity provide a ‘build’ flag that can enable them to run headless meaning it’ll just be the calculations that are enabled for that mode and will handle a ton of the game state sync, object references, hit detection, cool downs etc..But what I’m wondering is if this is the best approach? From my current understanding for each game running there would need to be a new instance of the headless game.exe running that will then create new connections for users into the game, sync up the players and start. This sounds very resource heavy (I might be overthinking it).

In the case of custom game server what would be a good approach into integrating the map data so that UE4 client map can be simulated on the back-end?

I can think of a simple solution looking at it from a 2D prospective, since it’s just X,Y we can create a bitmap/grid of position that are available, where walls are etc via simple tile tools that can be easily mapped 1:1 to the client and use that information. However when it comes to 3D I don’t see a solution on how to have a 3D map, collision detection and physics simulation.

networking – How do I get my modem’s IP address when using Google Wifi?

Occasionally I need to connect my ISP’s modem directly to initiate a restart.

Normally when I connect to my modem directly, I can either connect to the modem using the vanity URL provided by the ISP, or I can figure out the modem’s IP address, and connect to that (e.g. on macOS, option-click the network system menu icon, and observe the value for Router).

Problem is when I use Google Wifi as my router/access point, it’s no longer easy to find the IP address of the modem. Now the menu item shows me the IP address of the Google Router, and accessing it goes to a page that explains how to manage the Google Router.

How do I find the IP address of the modem which the Google Router is connected to?

linux networking – could not resolve hostname with ~/.ssh/config and aliases

I have a config file ~/.ssh/config that looks something like this:

Host *.texas
  User john

Host *.texas !gateway.texas
  ProxyJump gateway.texas

Host gateway.texas

Host dallas austin
  HostName %h.texas
  RemoteCommand zsh -l

In summary, I expect that ssh dallas resolves to something like ssh -J zsh -l while ssh houston.texas resolves to ssh -J The second example works as expected but not the first one (unresolved hostname). I suspect that it has something to do with the %h.texas which should in turn be resolved as

Could anyone help?


networking – How to set static ip on Hyper-V vm when host has one network card?

I am running Hyper-V on Windows 10 and created an Ubuntu server vm running postgresql. My pc has a single nic card.
There is a single network adapter on the VM that is connected to the Default switch in Hyper-V. I am able to connect to the internet from the vm and can connect to the instance of Postgresql on the VM from the host and everything works fine.
But each time I reboot the VM it gets a new IP address so everyday I have to reconfigure the connection string on my app that makes calls to the Postgresql instance on the vm.
How can I configure the ip addresses that are assigned to the devices on the vlan (not sure if that is the correct term) that are sitting behind the Default Switch? I am guessing there is a DHCP server somewhere but I can’t find anything.

I just want to have the same ip always assigned to the VM or be able to set the ip manually and know that it is not going to be assigned to another VM, but am at a loss as to how to do what seems like should be a super simple thing.

networking – Ping ip works but got “Temporary failure in name resolution” error pinging hosts

I have two Debian virtual machines named “server” and “client”. The settings are mostly the same.

When I ping “” on “server” I got no issue, but when I try pinging “client”, I got the “Temporary failure in name resolution” error. However pinging the ip addresses works.

My setings on “client”:

hans@client:~$ ip a s enp1s0
2: enp1s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast    state UP group default qlen 1000
link/ether 52:54:00:2b:40:ab brd ff:ff:ff:ff:ff:ff
inet brd scope global dynamic enp1s0
   valid_lft 3273sec preferred_lft 3273sec
inet6 fe80::5054:ff:fe2b:40ab/64 scope link 
   valid_lft forever preferred_lft forever
hans@client:~$ ip r
default via dev enp1s0 dev enp1s0 proto kernel scope link src 
hans@client:~$ cat /etc/resolv.conf
hans@client:~$ ls -l /etc/resolv.conf 
-rw-r--r-- 1 root root 25 May 28 06:46 /etc/resolv.conf

My settings on “server”:

hans@server:~$ ip a s enp1s0
2: enp1s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
link/ether 52:54:00:fa:5f:f7 brd ff:ff:ff:ff:ff:ff
inet brd scope global dynamic enp1s0
   valid_lft 2905sec preferred_lft 2905sec
inet6 fe80::5054:ff:fefa:5ff7/64 scope link 
   valid_lft forever preferred_lft forever
hans@server:~$ ip r
default via dev enp1s0 dev enp1s0 proto kernel scope link src 
hans@server:~$ cat /etc/resolv.conf
hans@server:~$ ls -l /etc/resolv.conf
-rw-r--r-- 1 root root 25 May 28 06:46 /etc/resolv.conf

Pinging on “client”:

hans@client:~$ ping
ping: Temporary failure in name resolution
hans@client:~$ ping
PING ( 56(84) bytes of data.
64 bytes from icmp_seq=1 ttl=52 time=263 ms
64 bytes from icmp_seq=2 ttl=52 time=256 ms
64 bytes from icmp_seq=3 ttl=52 time=257 ms

--- ping statistics ---
^C3 packets transmitted, 3 received, 0% packet loss, time 6ms
rtt min/avg/max/mdev = 256.464/258.557/262.566/2.835 ms

Pinging on “server”:

hans@server:~$ ping
PING ( 56(84) bytes of data.
64 bytes from ( icmp_seq=1 ttl=52 time=258 ms
64 bytes from ( icmp_seq=2 ttl=52 time=257 ms
64 bytes from ( icmp_seq=3 ttl=52 time=257 ms
--- ping statistics ---
4 packets transmitted, 3 received, 25% packet loss, time 8ms
rtt min/avg/max/mdev = 256.509/257.156/257.560/0.746 ms

the /etc/nsswitch.conf files on both hosts are the same.

networking – Internet connection drops for a few seconds

I am having a problem with an internet connection, let me explain:

I use my phone to connect to a WiFi network that uses EAP-SIM. In fact, every person who has a SIM card from the “Free” carrier can connect to these kind of WiFi Hotspots.

These hotspots are hosted from people’s routers in their home so I don’t really have access to the router configuration.

Then, I use a USB cable to tether connection to my PC running Windows 10. The problem is that when I watch Youtube videos or download things on the internet, the connection drops for some seconds then goes back normally and this happens multiple times.

I have managed to bypass this problem by using a connection to a VPN using OpenVPN client with the option redirect-gateway which is supposed to route all the traffic through the VPN network (This solution worked when using TCP for the VPN, on UDP I get the same problem…). I don’t know if this is some kind of throttling or if it is a problem with the connection.

Do anyone have an idea on how to fix this problem? Why does it work correctly when using a VPN with TCP?

Other things I have tried:
Changing the MTU for the network interface on my PC.

PS: This is my first post so excuse any missing information.

networking – Netgear Nighthawk ac1900 wifi usb on Ubuntu 20.04 LTS

This question has been asked a few times over the past few years on this forum. The methods that I found does not seem to work anymore, therefor I am here asking to see if anyone can help me to get it to work.

I bought the Netgear Nighthawk ac1900 wifi usb ‘model A7000’ and the only official drivers it has is the WINDOWS 10 and MAC-os. I am currently using a fresh install of Ubuntu 20.04 LTS.

networking – How to modify CSC file of samsung sm-j500fn?

My phone origin is the UK and I am in Sri Lanka now. My phone modemst1, modemst2 were reset and also I forgot to backup.

dd if=/dev/zero of=/dev/block/bootdevice/by-name/modemst1

dd if=/dev/zero of=/dev/block/bootdevice/by-name/modemst2

After reset it has asked to unlock the network.
I’ve tried many solutions such as flashing stock ROM of UK before I had custom rom(arrow os), zx3 tool pro. I could not do it. I don’t plan to buy a code since I think, It can be recovered.
I think it can be done via modifying the CSC file since it is specific to geographical region and carriers and it contains the software packages specific to that region, carrier branding and APN setting but I don’t have enough knowledge to modify the CSC file.
Another possible solution may be flashing the living country CSC file but I could not find CSC file only for my j5nlte phone with Sri Lanka.
Can anyone suggest how to modify the CSC file or provide any solutions to unlock the network in my device?
Thanks in advance………