DNS works only after I ping it [closed] - macos

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Actual problem is that I open VPN (OpenVPN) connection to my office on my mac.
This connection changes my preference to a new DNS (in office). I cannot visit any page until I manually ping dns by IP. After that everything works like a charm (until VPN disconnected, of course).
I really do not understand this behavior, but I am sure I can solve this because my colleagues (with Macs too) have no problems with this. Please, give me any hint how this can be fixed.

Maybe you need to flush the local DNS cache on your Mac:
dscacheutil -flushcache
Or maybe your local router onsite needs to flush it's DNS cache, especially if your mac is set up so that the local router is the gateway.
Before connecting, check your IP, gateway, and DNS, then connect (but don't do the ping thing yet), repeat, and then ping, and finally check again.
If this isn't illuminating, log into the local router's admin interface and do similar steps to the above.

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Can't access webservers on my oracle cloud instance, although I can SSH on 22 and ping the server IP [closed]

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Closed 11 months ago.
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I'm having a hard time viewing Wildfly welcome page on port 8080 + tried apache on port 80 too, and they timeout. I can ssh to the server and using (curl localhost:8080) and (curl localhost:80) show Wildfly and apache welcome pages respectively. I have checked the Security List and Security groups and even opened ALL traffic just to see if they are causing this problem, but unfortunately the problem still there.
I'm using ubuntu 20.04 image and the UFW (firewall) is inactive so the problem isn't from there.
By default every oracle instances come with 2 firewall.
Hardware Firewall (Known as VCN)
Software Firewall (They use a very hard iptables rules and regular ufw doesn't work with that.)
The 2nd option is very annoying and also took me about 3 days to solve my problem. You can follow my following instructions and hopefully it will also fix your problem.
1st you have to open the port on the Hardware Firewall (VCN) and when you believe you have opened the port then by login to the server using ssh use this command to clear the default oracle iptables rule.
sudo iptables -F
But remember whenever you will reboot the server you will need to again run the flash command. So if you don't want to run this command every time after server reboot. Then after running the flash command run this command to save your flashed iptables rules.
sudo netfilter-persistent save
So, you will not need to run the iptables falsh command every time on the startup of the server.

SSH Operation Time Out Trying to Login [closed]

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Please forgive the embarrassingly dumb newb question.
Here's the scenario:
As part of a task I have to SSH into a server and create some files. I was given the servers name (some.server.com) and an SSH key (id_rsa.username) to use. I am told to use the username and the provided key to login. Since I am relatively new to the workings of SSH this is what I have done:
I have downloaded id_rsa.username to my Downloads directory.
I have tried loggin in with
ssh -i downloads/id_rsa.username username#some.server.com
But I get ssh: connect to host some.server.com port 22: Operation timed out
I have tried using port 2222 and also 11234 ( I used that port once on a different server).
Is there anything I am doing wrong on my end? I don't have access the server admin to ask any questions so I have to try to figure this out myself.
in my case, I change the rule of ufw, and that rule ban the ssh connect
so run sudo ufw allow sshsolve the problem
"Operation timed out" means that you're not making a TCP connection to the remote server. The remote computer may be down, or there may be a firewall blocking access to the the remote server, or your local computer may not have suitable network access. It's not really possible to say what the exact problem is, based on the information here.
If you're in a corporate network, you should contact your local computer support staff for assistance. It's not unheard of for companies to block outgoing SSH from their corporate network.
Otherwise, if you need help troubleshooting network connectivity, you'd probably get better results on Superuser.

ping to iis hosted web side does not working [closed]

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I have a web side hosted on IIS, windows 8 os. I can access from my browser to this page via these urls:
localhost/mysamplesite
192.168.21.10/mysamplesite
I can ping my ip address like this: ping 192.168.21.10
But I can not ping to 192.168.21.10/mysamplesite this command gives error: ping request could not find host 192.168.21.10/mysamplesite
Actually have another machine (192.168.21.45) that installed apache banchmark on. I want to test request from apache banchmark to my site. So I can not send request.
ab -n 1 -c -1 192.168.21.10/mysamplesite
This does not work.
As arco444 mentioned, you can't ping a website, just a computer itself.
ping is the first thing to try when troubleshooting network connectivity problems
ping 192.168.21.10
from the remove machine.
You can also try PsPing to test for connectivity to a certain port:
psping 192.168.21.10:80
however you can not use this to check for a particular resource on your web site.
Instead you have to use a tool to test for http traffic, Apache Benchmark is one of them, depending on the OS on the remote machine, there are many other tools.
If ping works, check the firewall settings on your Windows 8 machine.

i want to host a website behind NAT [closed]

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I am using internet behind NAT, of my institute. I have no access to router's username and password. I want to host a website from my laptop. Is there any way I could host it?
That really depends on the configuration of the main router, but the answer is probably "no". Most likely main router doesn't forward any ports to your laptop.
Of course there are workaround, like for example, setting a VPN or SSH tunnel connection to another server that will forward ports to your computer, but if you'll have access to the server that is already accessible from the internet - you'll just host your site there.

Remote Desktop can't connect to the remote computer for one of these reasons [closed]

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I am able to ping the IP-address of a machine but I am unable to establish a remote desktop connection . When I try to do so it says:
Remote Desktop can't connect to the remote computer for one of these
reasons:
1) Remote access to the server is not enabled
2) The remote computer is turned off
3) The remote computer is not available on the network
Make sure the remote computer is turned on and connected to the network, and that remote access is enabled."
...any help?
If you can ping it, it means it's turned on. If you can ping it, it means the computer is available on the network... which one of the possibility remains? Only one.
Check your firewall rules. Check that VNC Server (or whatever service are you trying to use is running properly). Without other details, our answer can't be more precise.
However, this question is likely to be migrated to http://serverfault.com.
I am assuming you haven't turned off the remote computer, so let's look on the other parts of the error message, i.e. 1) and 3).
As part 1) of the message suggests: Most likely you haven't enabled remote access on the remote computer yet.
How you can enable it, is described here on the SuperUser forum.
Regarding the other reason mentioned by the error message ("2) The remote computer is not available on the network"):
The link above also describes how you can change the default listening port 3389 for RDP (remote desktop protocol) in case it is blocked by the firewall.
Please check as well, if you need a VPN tunnel to establish a remote connection. This is the case in most corporate networks (especially if you're working from home).
Last, but not least, check that your network is running as it should (VDSL or cable modem/router) - keep in mind your modem/router usually also has a firewall: check it and find out if it is blocking.
Finally, one reason could be that the hostname you entered cannot be resolved by DNS (domain name service). Check if you configured DNS correctly on both PCs - and as workaround you can use the remote PCs IP address to connect.

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