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I was having issues sending emails from my android device using k9 mail.  I have some pretty strong rules in /etc/postfix/header_checks file.  To test if this was the cause I renamed the file.  I then restarted and sent a test email. I found that once I did that I received a different message when a test email failed to be sent.  The error was "Error: queue file write error". Aug 8 10:24:19 mail postfix/cleanup[2324]: warning: regexp:/etc/postfix/header_checks is unavailable. open /etc/postfix/header_checks: No such file or directory So, you have one possible solution to that error.  It is that header_checks is missing.  When you perform tests like I did you should always ensure that you have a dummy file with that name.  Restart the server and try another test email. Or find…

Now that I've explained some about SSH and the concept of a jump server (a secondary machine that takes requests and proxy forwards them to other machines on the LAN that are not exposed to the Internet) I'll continue by explaining how to conceptually configure a jump server.  I'll start by reiterating a little about how one works and why we'd use it. A jump server provides extra layers of protection from the bad guys and script kiddies on the Internet.  What you may not know, understand, believe is that someone is attacking your computers (including your phones -- whatever has an OS they are probing and trying to exploit) at your location all the time from all over the world.  There's a whole computer discipline (field of study) about…

SSH means Secure SHell.  It is a method of connecting to remote systems.  You use a terminal program to connect and login to that remote system.  If you are familiar with Linux you know you have a terminal prompt that you can access through a program like Konsole or gnome-terminal.  In the terminal you issue commands.  You issue commands by typing them at the prompt, just like in the old days of DOS. What makes SSH special is that you can use it to connect to a remote computer and issue commands as if you were physically sitting in front of that computer itself. Connections consist of using the SSH command with the terminal program open.  With it you connect to the remote system by issuing the SSH command.  You…

This is kinda a pet peeve with me.  I hate spam.  I have my own email servers hosted locally at my shop because I dislike other entities contacting me without my explicit permission.  If I suddenly get spam from some entity I want to ensure I have full control to block everything from their domain.  That is what I thought I had done and it seemed to work for some time, however, I started getting spam from several entities that I thought I had blocked, and after checking found that I had blocked them. I went looking for answers and found the answers were in the details.  I read posts pretty fast and sometimes just exclude them from the solution due to how little detail or how much detail they…

This has been an ongoing for some time and various things have been done in an attempt to resolve it.  Much of that consisted of swapping out cables and switches, testing hardware, doing a test install, and disconnecting VLAN segments,  I also bought an inexpensive replacement cable modem just in case thinking that it may be the issue.   I didn't test that as I hadn't eliminated the pfsense setup as the cause, nor for that matter any of it except some specific hardware such as switches and cables.  All told, I had swapped out multiple cables and switches, some a couple of times.  After eliminating those I put everything back to the way it was and went onto the next step. At times I thought I had narrowed it…

This is one of those thigns that has been bothering me.  I want to limit who can access the wp-admin folder and hence the admin login script.  I've read about how to do it online but have had no positive results.  Apparently when Apache updated the software to 2.4 the game changed and how you use certain features that worked with 2.2 do not work with 2.4 and there's no certain way to testing this absolutely.  What I mean is that I can try them  and then see if I can log in but because of other issues with how apache 2.2 directives may interfere with 2.4 directives causing them all to fail it is not clear which ones correct.

With the samba issue resolved (by removing the mount to the other server) and testing for disconnects the same thing happens.  So, that didn't resolve it.  This has been ongoing for a long while and is quite disconcerting.  I have found a way to mitigate the impact of loosing the connection by using a linux program called "screen".  However this is not the perfect solution.  I have to remember to start it after each connect.  Then if I get a disconnect I need to restart it by attaching to the screen session.  Then I have control of the prior tasks. Since the attempt to resolve it last, I added a second gigabit network card (NIC) and tested more.  Same issue.  That means it isn't the NIC that was the issue. …

Just out of the blue I started getting disconnects both locally and over the internet when I used SSH.  For years prior to this everything just boomed along.  Nary an issue to speak of.  But all of the sudden out of the blue these disconnects started happening and the tasks that were running over SSH were dropped, often resulting in me taking a lot of extra effort to correct or restart the task. This is annoying.  And since it was random and even when something was happening down the channel and it would affect every device no matter what it was doing I've been growing disconcerted. I did look into this.  I tried to remember things that had changed.  Some of those changes were like: I picked up three used…

This error is quite common and has numerous causes. I've used samba on Linux for a long time. I've never seen this error. When I finally did have the error I went looking for a cause. A lot of people had answers but none of them resolved the issue for me. What I was doing was setting up a Proxmox virtualization server. It uses LXC. I also have a VLAN that doesn't route to the inside LAN. I needed to send backups of containers from the virtualization server to a backup server. Since I had UFW installed and configured I checked to see if the ports for SAMBA were open. They were not. I do not just open ports to any computer, even internally. So, I opened the necessary ports…

OK, Postfix is the main tool that I use to run my email services. The goal/hope is to be able to be low on the list of people that are hacked, unlike those that are part of the aggregation services such as gmail, outlook, and yahoo. Yahoo BTW had all their billion plus users hacked and didn't disclose that to us promptly. It would have remained hidden if it weren't for the sale. Postfix is a tool that allows you to run an email service right out of the box, but obviously there are things that must be done to make your email known to the rest of the world. If you don't let your server be known well, no mail will ever get to you. How do we let…