CentOS x11 Forwarding issue - centos

I am on a Windows7 machine and I'm trying to get graphic view on the centOS machine to be displayed on my current screen. When typing xclock, gedit... in terminal, I am getting the following error
-bash: xclock: command not found
and This the result of # vi /etc/ssh/sshd_config command
# Example of overriding settings on a per-user basis
#Match User anoncvs
# X11Forwarding no
# AllowTcpForwarding no
#tewayPorts no
#X11Forwarding no
X11Forwarding yes
#X11DisplayOffset 10
#X11UseLocalhost yes
Also Xming is running on server:0.0 and I turned X11 forwarding on on putty
So what's the problem ?

sudo yum install xorg-x11-apps
Should cover it!

Do you have an .Xauthority file in your home directory?
I've recently found the answer for my issue, which might be similar to yours. I've seen quite a few open questions about this topic without resolution. You may have a few more things to work through, but SELinux settings ended up being my final hurdle. This among many other steps are covered here: ssh X11 forwarding won't work
That aside, you may need to change the Xming settings to match the default DisplayOffset of 10 for Centos. And after any changes to sshd_config, you'll need to restart the service via
/etc/init.d/sshd restart
I would like to emphasize that my situation is a non-critical operation within a (hopefully!) securely-managed intranet. I would NOT suggest turning off SELinux at work, or at home if you're hoping to open ports or configure VPN for your home network. Please consider: http://securityblog.org/2006/05/21/software-not-working-disable-selinux/

Related

KeePassXC won't add keys the running SSH agent when started from the gnome shell

I am running on Pop!_OS so for most things this is likely an aquivalent of Ubuntu.
KeepassXC is installed and the SSH-Agent is enabled.
There is a keyphrase configured with a key and it works just like a charm when I start keepassxc from the terminal keepassxc log in and then I can see that ssh-add -l lists an additional key. It also vanishes once I close KeePassXC. Perfect!
Now I start keypassXC from the gnome shell, hit the super key, search for keepassXC and log into its vault. Looking at ssh-add -l in the terminal: Nothing. No keys added. 😔
Now I took a look at /usr/share/applications/org.keepassxc.KeePassXC.desktop and changed Terminal=false to true. No, sadly not that easy.
My guess that it has something to do how the gnome shell starts KeePassXC, but can't say for sure what the problem is. Anyone got a clue what that could be or how to take a shot at the problem?
I got the KeepassXC ssh agent working on Ubuntu 16.04.6 with Unity as the window manager.
The issue is that if the SSH_AUTH_SOCK environmental variable is not set before the window manager starts it is not available for programs started in the window manager.
Some distributions have a system for starting programs such as the ssh-agent before the window manager. On my distro I found that /etc/X11/Xsession.d/90x11-common_ssh-agent was starting ssh-agent. See this comment on a user help issue for KeepassXC for more information.
However I also found that GNOME Keyring was starting an ssh agent of its own. I had to disable this in the startup applications. I also checked that no shells startup scripts (ie. .bashrc .bash_profile .profile .config/fish/config.fish were trying to start the ssh-agent, as doing so would replace the one started before the window manager.
An interesting side note, the ttys, that you get to with Ctrl+Alt+F1, Ctrl+AltF2, etc., also do not have the SSH_AUTH_SOCK environmental variable set as they start up before the window manager. If you need it here you can add code to find and set the SSH_AUTH_SOCK. For the fish shell I added the following to ~/.config/fish/config.fish:
# Set SSH_AUTH_SOCK if not set.
if test -z "$SSH_AUTH_SOCK";
set -gx SSH_AUTH_SOCK (find /tmp/ -path "/tmp/ssh-*/agent.*" 2>/dev/null)
end
I also found that in the upcoming 2.6.0 release of KeepassXC (targeted for 3. April 2020), there will be an added settings to allow overriding, or settings the value to use for SSH_AUTH_SOCK. However as this changes each time ssh-agent starts you will either need to keep changing it or set-up a link that would point to the current sock.

sshd#QNX: Could not load host key / Missing privileges separation

I followed the manual provided by QNX for SDP 6.6.0 on how to set up the OpenSSH SSH daemon except I tried to get it running on an existing Neutrino OS. To no avail so far. I encountered several pit falls which I could not find to be solved in any guide I found on the web.
It works quite easily and out of the box for QNX 6.5.0. E.g.
'How do you install an ssh server on qnx' which only states to generated keys and start the daemon. But that doesn't seem to be the case anymore.
This is how I've tried to tackle this so far:
created folder /etc/ssh and DSA and RSA keys
tried starting sshd => error: /etc/ssh/sshd_config
created empty file /etc/ssh/sshd_config
tried starting sshd => error:
Could not load host key: /etc/ssh/ssh_host_ecdsa_key
Missing privileges separation directory: /var/chroot/sshd`
created folder /var/chroot/sshd and file /etc/ssh/ssh_host_ecdsa_key with proper privileges using chmod 700
P.S.: Why is it that there are only very very few sources actually talking about SSH and QNX. Even QNX only refers to NetBSD by linking their plain man pages. In the BSP guides they handle the topic like "Yeah we've got SSH - you can use it." If not SSH what's then the proper way of remote access?!
OK, gonna answer my question rightaway (since after not posting it, I found the answer some days later):
Long story short. The ssh version on QNX 6.6.0 needs also the ssh_host_ecdsa_key key file generated using ssh-keygen -t ecdsa -f /etc/ssh/ssh_host_ecdsa_key. The file was present at my system but somehow corrupted and I just had to generate it again. (I did not know that back then and the manuals I was following don't even mention this key)
I would not recommend following the QNX manual (since it's outdated and especially) if you simply just want to start/configure the sshd daemon (ssh server) on an existing system. Follow 'How do you install an ssh server on qnx' instead.

Vagrant is attempting to interface with the UI in a way that requires a TTY

Problem: vagrant up fails with the error below. I am running vagrant on Windows 7 and the base box is Ubuntu )( files.vagrantup.com/precise32.box ).
how can it be fixed?
vagrant.bat up
Bringing machine 'default' up with 'virtualbox' provider...
[default] Clearing any previously set forwarded ports...
[default] Clearing any previously set network interfaces...
[default] Available bridged network interfaces:
1) Intel(R) PRO/1000 EB Network Connection with I/O Acceleration
2) Intel(R) PRO/1000 PL Network Connection
Vagrant is attempting to interface with the UI in a way that requires
a TTY. Most actions in Vagrant that require a TTY have configuration
switches to disable this requirement. Please do that or run Vagrant
with TTY.
Process finished with exit code 1
thanks
This worked for me on cygwin:
Or add this to ~/.bashrc:
export VAGRANT_DETECTED_OS=cygwin
Then I got the "Vagrant displays a message that it needs to run some internal upgrades..."
Edit - Oops! Spoke to soon. During its updates, I got Warning: Authentication failure. Retrying... until timeout :P
Edit 2 - I was able to fix it by setting config.ssh.private_key_path to the .vagrant.d/insecure_private_key in my Windows user's home directory.
I had the same error while destroying a Vagrant Box. I simply added -f and it did the job.
vagrant destroy m001 -f
This is happening because when script attempts vagrant destroy, Vagrant asks for [Yes/No] confirmation. Adding -f skips that.
I got the same error after upgrading Vagrant from 1.4 to 1.6.3 (Windows 7).
Running VAGRANT_HOME\bin\vagrant.exe manually resolved this issue for me:
Execute VAGRANT_HOME\bin\vagrant.exe
Vagrant displays a message that it needs to run some internal upgrades
"Press any key to continue"...
Once the process finished (it took several minutes), I was able to proceed with Vagrant instance launch as usual.
This is caused by Vagrant finding multiple Ethernet interfaces that can be used as public network and Vagrant cannot decide which one to use.
There are 3 options:
Deactivate one of the 2 adapters, so that Vagrant can use the other
Specify the Ethernet adapter you would like Vagrant to use in the vagrantfile. Like this:
app.vm.network "public_network", bridge: "Intel(R) PRO/1000 PL Network Connection"
Running the vagrant executable manually as already described in Al Belsky's answer
If you are on Windows and are starting Vagrant through MinGW (Git Bash for example) and get this message, try running it once through Windows' default cmd.exe. You are then able to answer the question about your network adapters.
I'm using Vagrant 1.7.4
Execute the below code before running vagrant up:
export VAGRANT_DETECTED_OS=cygwin
That will eliminate the exiting of vagrant and will allow you to choose Network Interface.
This may also be caused by not having Hardware Virtualization enabled in BIOS.
Also encountered this with Windows 10, when Vagrant cannot properly detect OS.
also can happen if you have both vmware and virtual box installed and you try to use MinGW.

Cannot SSH into new computer running CentOS 6.3 from Fedora 16

I just installed CentOS 6.3 on a new computer and am unable to SSH to it from our computer running Fedora 16. They are both on the same network.
Some facts:
- I can ping it from the Fedora machine.
- I can SSH to the CentOS computer to itself on the CentOS computer.
- I have looked into hosts allow and deny, I have set selinux to be permissive, I tried with iptables disabled on the Fedora computer
I am fresh out of ideas...
Thanks
Do you have fail2ban running?
Do you have denyhosts running?
Do you have iptables allowing TCP 22?
Do you have a line in your sshd_config that refers to "AllowUsers"? (most dont but some do, and if yours does, you need your account listed on that line)
Can you run this command tail -f /var/log/secure on that machine at the same time while trying to login from the second machine and spot the issue? If not, paste the output from that log here for me to comment on.
A long shot, but you might try service sshd restart and try again to see if that helps. Go ahead and run tail /varlog/messages while restarting that daemon to see if you spot anything unusual while doing that. If you spot the issue great, if you dont, post the output here for me to comment on.
Last, do this cp /etc/ssh/sshd_config /etc/ssh/sshd_config.back and then take a good known working sshd_config from another machine and place it over the top of yours and then restart the daemon again & try again.
My money is on seeing something that helps us in /var/log/secure.

How to use RDC with VirtualBox and OSX

I'm trying to do some local RDC testing using VirtualBox. The host is OSX.8, the VM is ubuntu, and VirtualBox is version 4.1.22.
The VM starts fine without any problems. I shut it down and choose "Enable Server" from the Remote Display section of the Display options and start again, and again it starts fine. Note that the port is left default and the authentication is "null".
I start Microsoft's RDC (v2.1.0) and type in 'localhost' and get: You were disconnected from the Windows-based computer because of network problems.
I try 127.0.0.1 and get the same error. Then I type in the IP of my (host) computer and get the same error. I know the loopback address avoids the firewall but I turned it off anyway and got the same error.
I get the same error whether I'm using NAT networking or bridged. What am I doing wrong?
I should note that this is a vanilla install of VirtualBox and I haven't added any extensions or guest additions or anything like that.
Seems I'm doing everything right. What am I missing? Thanks for the help!
Problem Solved! You have to install the "VirtualBox 4.1.22 Oracle VM VirtualBox Extension Pack" (available on the VB download page) to make RDC work. I wish it would tell you this when you click "enable server" but I guess that's asking too much. I hope this helps someone else.