gen_Eric's questions

I have two servers on the same network. One running Windows Server 2016 and another running CentOS 8. The Windows server is my main file store, it's where all my data is. The CentOS server has the Windows share mounted and can access its files.

On CentOS, I've setup a samba share. Why? Because I have a webapp running on that same server and I want the webapp to control who can access what file. So, instead of having our (internal) users mount the Windows share directly, they'll be mounting the CentOS share which will be "gatekeeping" access to the files.

In the samba folder, there are folders for each user and a config to allow users access to just their folders. The webapp is configured to add symlinks into these folders that link to the "real" files.

This is where the issue is. If I add a "normal" files into a user's folder, they can access it just fine. But if I add a symlink (to a file in the mounted Windows share), it doesn't appear for them. I'm pretty sure this is an SELinux issue.

Here's how things are setup.

• The Windows share is mounted

  sudo mount -t cifs //WindowsShare/data /media/WinShare \ 
    -o ip=192.168.1.5,username=user,gid=sambashare
  
  ls -alhZ /media/WinShare
  drwxr-xr-x. 2 root sambashare system_u:object_r:cifs_t:s0  0 Jan 10 16:57 files
  

• A samba share is created and uses /srv/smb (all samba users are in the sambashare group)

  ls -alhZ /srv
  drwxrwx---.  2 root sambashare unconfined_u:object_r:samba_share_t:s0    6 Jan 13 11:20 smb
  

• The /etc/samba/smb.conf has the following:

  [global]
      allow insecure wide links = yes
      unix extensions = no
  
  [adminShare]
      path = /srv/smb
      wide links = yes
      follow symlinks = yes
  

• As a test, I added a symlink and a file

  ln -s /media/WinShare/files/test.pdf /srv/smb/test.pdf
  touch /srv/smb/file.bin
  

Then I tried to mount \\CentOS\adminShare in a Windows VM and I don't see the test.pdf file but I do see file.bin.

How can I give the CentOS samba share access to the mounted Windows Server data? When setting up the CentOS server, I ran:

sudo semanage fcontext -a -t samba_share_t "/srv/smb(/.*)?"

This is what allowed me to see file.bin, but I still can't see file.pdf. I found this, but I don't know if I want to change everything:

sudo setsebool -P samba_export_all_rw=1

How can I allow samba to access the /media/WinShare folder? Would this work?

sudo semanage fcontext -a -t samba_share_t "/media/WinShare(/.*)?"

I am running Arch Linux and on top of that, Ubuntu inside a systemd-nspawn container. I am suddenly having issues getting apache to start (inside the container).

Everything was working fine a few days ago, but now it's not. I don't know if an update inside or outside of the container has changed something.

Inside the container, I see the following:

root@container:~# apachectl -k start
/usr/sbin/apachectl: 99: ulimit: error setting limit (Operation not permitted)
Setting ulimit failed. See README.Debian for more information.
(13)Permission denied: AH00072: make_sock: could not bind to address [::]:80
(13)Permission denied: AH00072: make_sock: could not bind to address 0.0.0.0:80
no listening sockets available, shutting down
AH00015: Unable to open logs
Action '-k start' failed.
The Apache error log may have more information.

I checked using lsof and netstat and nothing else is running on ports 80/443. Also, what is that "ulimit" error? What's going on there?

I did use sudo systemctl edit [email protected] to edit the settings to disable private networking and enable some bind mounts:

[Service]
ExecStart=
ExecStart=/usr/bin/systemd-nspawn --quiet --keep-unit --boot --link-journal=try-guest -U --settings=override --machine=%i \
        --bind-ro=/etc/resolv.conf:/etc/resolv.conf \
        --bind=/home/nticompass/Code/website:/opt/website

Yes, the apache config inside the container is setup to use /opt/website as its root. I have it bind mounted so I can use my IDE on my main OS (Arch Linux) to edit the files and then have the container be able to access them (without having to copy/transfer them).

I am not sure what to do here. Did something change in an update? Do I need to update a config on my Arch Linux? Why can't the container access the ports? What is that "ulimit" error?

EDIT: Here is a list of packages that were upgraded/installed in the last week on my Arch Linux (main) system: https://pastebin.com/5xyGpBrw

In our office building, we have a Cisco SRW2048 switch. On the back, it has a serial port for console connections. I would like to connect this console port to my computer in my room.

The switch is located in the network room next to the ethernet patch panel which leads to all of the other rooms. I was wondering if it was possible to use that patch panel to connect to the switch's console port.

Would it work if I used 2 rollover cables? Like, if I connected one from the switch to the patch panel and another from the ethernet port in my room to the serial port on my computer?

If not, is there another way to connect to the switch without running a super-long serial cable along the floor from the network room to my room?

UPDATE: Yes, I know I should be using the web interface (or telnet) to access the switch. I just want to connect to the console port as a learning exercise or, you know, just for fun.

I'm just not sure what cable/adapters to use, since in the lab in school, the router/switches had RJ45 connectors as their console ports and we used rollover cables to connect to them. This switch has a RS232 (serial) connector as its console port and I wasn't sure how to interface with it through the ethernet patch panel.

UPDATE 2: Could I use a rollover cable on one end and a "null modem" adapter on the other?

I am running a Windows Server 2012 installation inside VMWare Workstation. I have shared folders enabled, so drive Z: is mapped to \\vmware-host. I can correctly access this drive in Explorer (I can access Z: inside the "normal" `cmd) and I can properly open files.

I opened PowerShell and tried to to cd Z: and I got the following error:

cd : Cannot find path 'Z:\' because it does not exist.

Why can't PowerShell find the already mapped network drive?

I Googled a bit, and found the New-PSDrive command. I ran the following:

New-PSDrive -Name 'Z' -PSProvider FileSystem -Root 'Z:\'

but I still get the same error as above. What do I need to do to access the VMWare shared folders inside PowerShell.

I have a wildcard SSL for my website, but I'm getting a strange error in my web browser(s).

You attempted to reach app.dev.mysite.com, but instead you actually reached a server identifying itself as *.mysite.com.

_{(This is what Chrome tells me is going on)}

I don't understand this error. I thought wildcard SSLs meant that it would work on any subdomain of my site? How the heck does app.dev.mysite.com not match *.mysite.com?

Oddly enough, app.mysite.com works just fine with this SSL. What is going on here? Is there an apache setting for this?

P.S. My domain/SSL is through GoDaddy.

While SSHing into my server with an RSA key, I get this message:

Address 255.100.236.105 ¹ maps to a1.example.com, but this does not map back to the address - POSSIBLE BREAK-IN ATTEMPT!

Even though I get this error, I am still able to SSH into the machine.

I examined the DNS and figured out the issue. This server has lots of vhosts, so we have multiple A records for the same IP address.

For example:

A a1.example.com 255.100.236.105
A ssh.example.com 255.100.236.105

(there are a few more that point to the same IP)

I am trying to SSH to ssh.example.com, and I am getting the above error. How do I get SSH to realize that the IP has multiple domain names that point to it?

NOTE: I can't ssh to a1.example.com because that subdomain is going through CloudFlare's proxy.

UPDATE: I tested this on two computers. One gave me that error, one did not. Why would that be?

_{¹ This is a fake IP, I made up. I'm not sure if it really points anywhere.}

I am running a Samba server on a Debian box. It works fine; Windows can read and write to it just fine, but there's one issue.

The folder I'm sharing over Samba (/var/samba) is stored on my main drive, which is an old 40GB IDE drive. Inside that folder are symlinks to other folders on my system, 2 of which are actually on my 1TB SATA drive.

In Windows, I have the Samba share mapped to a drive letter, and it says there is only 9GB remaining (which is how much space is left on the server's root drive (40GB drive)).

Can I tell Samba to report that a different amount of free space is remaining? I was trying to make a Windows backup into one of the folders that's symlinked to the 1TB drive (yes, there's enough space remaining on that drive), but Windows won't let me because it thinks there's not enough free space left.

I am using the file uploader plugin (from: https://github.com/valums/file-uploader) to upload files to my website.

If you are using a moden web browser (like Firefox 6 or Chrome 13), then it uploads by streaming the file in the POST body, and can give you a progress bar. If you're using IE (or an old browser), it falls back on the standard $_FILES (using a hidden iFrame).

Everything was working fine, but suddenly I can't upload 5MB files in Chrome or Firefox. When I upload a 5MB file in Chome or Firefox I get a 500 error and my PHP code is never even ran. If I use Internet Explorer (which uses $_FILES), it works fine.

This has to be a configuration problem, as my PHP code never even runs. So, I checked my settings.

/etc/php.ini

upload_max_filesize = 15M
post_max_size = 16M

I looked for LimitRequestBody, but that's nowhere to be found (and the default is unlimited).

Settings look right. I debugged this for a while, and I can not figure out what is wrong.

Is there a setting I'm missing? The server has suhosin installed, if that matters.

I know my PHP code works, as files less than 4MB upload fine (on all browsers). I only have a problem with files bigger than 5MB (using Chrome/Firefox). The weird thing is, this works fine on my test server, but not my production server. They probably have different settings (suhosin is on production, but not on test).