• pptp / pptpd not working in DD-WRT iptables / router


    Although it is well-known that pptp is not secure and is subject to many forms of attacks, the reality is that a lot of legacy and embedded devices use pptp. I argue that if it is being used for routing or remote access or over an already secure connection (eg. another VPN like ikev2) then this is still acceptable. Or in a LANor in a public environment where no private data is exchanged. However, if the nature of the data is extremely sensitive, you should do whatever........
  • nvidia cannot resume from sleep Comm: nvidia-sleep.sh Tainted: Linux Ubuntu Mint Debian


    This seems to happen in many different drivers but it happened more often in newer versions such as 530 vs 525. Then nvidia-modeset goes to 100% There are many reports of this appearing since driver 4.70 and I can confirm I've seen this in various machines. https://forums.de........
  • Postfix / sendmail config for DKIM, SPF and DMARC Tutorial Guide E-mail Delivery for Hotmail.com Gmail.com and More HowTo


    This will be the goto to help solve e-mail delivery issues and talk about many practical issues that happen between developers, admins and scripts that send e-mail and do things that may not be acceptable or cause deliverability problems. Sendmail Stuff Edit /etc/mail/sendmail.mc The problem is that if you send directly out from the server using the mail function, the Return-path of the e-mails will be username@thehostnameoftheserver.com. Let........
  • Virtualbox Best Networking Mode In Lab/Work Environment without using NAT Network or Bridged


    Virtualbox is a very powerful tool, but for some use cases it is less than optimal. Say you are in a work, lab or other environment where you are not alone on the physical network and there could be overlap of IPs, but you need all of your VMs to be contactable from your host, VMs need to communicate with each other, and VMs need internet. NAT Network will give you VM to VM communication and internet, however, it is buggy and unstable. It also doesn't allow host to VM co........
  • ssh forward multiple ports in the same connection and command even works with NAT!


    You can actually just pass multiple "-L" statements to achieve this. An example is as below: ssl -L 80:192.168.10.5:80 -L443:192.168.10.5:443 -L2068:192.168.10.5:2068 -L 8192:192.168.10.5:8192 user@remotehost.com The above essentially is saying forward ports 80,443,2068,8192 to the remote IPof 192.168.10.5 (even though it is behind NAT). Essentially SSH will do the NAT part even if the........
  • iptables how to forward localhost port to remote public IP


    iptables -t nat -A OUTPUT -m addrtype --src-type LOCAL --dst-type LOCAL -p tcp --dport 3306 -j DNAT --to-destination ip.ip.ip.ip iptables -t nat -A POSTROUTING -m addrtype --src-type LOCAL --dst-type UNICAST -j MASQUERADE sysctl -w net.ipv4.conf.all.route_localnet=1 Make sure you substitute "ip.ip.ip.ip" for your real public IP and also the "--dport 3306" for the port you want to forward. Finally run the sysctl command and........
  • iptables redirect ports to a different host and port + NAT Masquerade howto/solution


    This is important if you need public access to internal IPs such as at your office and don't want to use a VPN just to SSHinto different servers: Below forwards the port "10001" to the IP192.200.5.53 on port 22 (of course adjust it to your needs). iptables -t nat -A PREROUTING -p tcp --dport 10001 -j DNAT --to-destination 192.200.5.53:22 Remember to enable MASQUERADE on your NAT IPs or they won't be able to talk to the outside world (........
  • Setup PXE Boot using Centos and dhcpd, tftp and syslinux


    This is something I often setup for clients because it's very helpful for people in datacenters, this allows custom OS installs on demand, you can customize it more by using kickstart etc.. but here's a base I use before customizing more: This little script below will install everything you need to get booting by PXE Linux. It also assumes you set a local IP (be sure not to overwrite your existing IP) on eth0:0 (note the :0) as 192.168.1.10 and it........
  • OpenVPN don't use bridgestart.sh or bridge at all use iptables


    I used the suggested script to bridge from OpenVPN and it took my client's server off-line! Don't ever use their "sample" scripts if you don't have another way of accessing the server than SSH. I actually found it easier to use iptables to tell it to route IPs based on a certain subnet to route through eth0: iptables -t nat -A POSTROUTING -s 192.168.200.0/24 -o eth0 -j MASQUERADE Replace "192.168.200.0/24" with your subnet of cour........
  • Latest Articles

  • Bad Power Supply Issue Story Diagnosing Troubleshooting
  • Getting started with AI (Artificial Intelligence) in Linux / Ubuntu using by deploying LLM (Language Learing Models) using Ollama LLMA
  • microk8s kubernetes how to install OpenEBS
  • Flash LSI MegaRAID 2208 to IT mode in Linux Mint/Debian/Ubuntu
  • LSI MegaRAID in Linux Ubuntu / Centos Tutorial Setup Guide megacli
  • Convert-im6.q16: attempt to perform an operation not allowed by the security policy `PDF' @ error/constitute.c/IsCoderAuthorized/413. convert-im6.q16: no images defined `pts-time.jpg' @ error/convert.c/ConvertImageCommand/3258. solution ImageMagick P
  • Apache PHP sending expires header solution cannot use cache with CDN
  • How to install virt-manager in Mint 22/Ubuntu 22
  • Infiniband Guide
  • python mysql install error: /bin/sh: 1: mysql_config: not found /bin/sh: 1: mariadb_config: not found /bin/sh: 1: mysql_config: not found mysql_config --version
  • FreePBX 17 How To Add a Trunk
  • Docker Container Onboot Policy - How to make sure a container is always running
  • FreePBX 17 How To Add Phones / Extensions and Register
  • Warning: The driver descriptor says the physical block size is 2048 bytes, but Linux says it is 512 bytes. solution
  • Cisco How To Use a Third Party SIP Phone (eg. Avaya, 3CX)
  • Cisco Unified Communication Manager (CUCM) - How To Add Phones
  • pptp / pptpd not working in DD-WRT iptables / router
  • systemd-journald high memory usage solution
  • How to Install FreePBX 17 in Linux Debian Ubuntu Mint Guide
  • How To Install Cisco's CUCM (Cisco Unified Communication Manager) 12 Guide