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Jeroen W. Pluimers on .NET, C#, Delphi, databases, and personal interests

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Archive for the ‘*nix’ Category

When your triple/quad-play providers refuse to give your VoIP SIP credentials, but allows access to your modem: use Wireshark on the LAN side

Posted by jpluimers on 2019/04/12

Every now and then I hear about providers that refuse to hand over the VoIP SIP credentials.

If you do have access to your modem, you can Wireshark the WAN side, then reset the modem and capture traffic until it has obtained the VoIP information:

[WayBack] Telfort SIP (getest met Glasvezel) | Het leven van Teus & Simone:

Veel mensen op het forum van Telfort vragen zich af of ze de SIP gegevens kunnen krijgen voor telefonie zodat men de ExperiaBox niet hoeven te gebruiken. Gezien dat de Telfort Support deze gegevens…

Via:

–jeroen

Posted in *nix, *nix-tools, Internet, Power User, Wireshark | Leave a Comment »

crontab.guru – the cron schedule expression editor

Posted by jpluimers on 2019/04/12

Confused by crontab expressions? Me too, so I was happy to find: At minute 3 past every 12th hourcrontab.guru – the cron schedule expression editor.

It has a [WayBack] truckload of common crontab expressions, but more importantly allows you to live edit one, then explains in human terms what it means and when the schedule runs next.

If you like a step by step cron configurator, then you can try [WayBackCron Job Generator by GenerateIt.net but need to note it cannot interpret a cron expression.

–jeroen

Posted in *nix, *nix-tools, cron, Linux, Power User | Leave a Comment »

ssh from Mac OS X to ESXi: “WARNING: terminal is not fully functional”

Posted by jpluimers on 2019/03/29

When connecting from my Mac to my ESXi rig, some commands (especially less) show this output:

WARNING: terminal is not fully functional

So I created this alias to connect from my Mac to the internal address of my ESXi rig:

alias ssh-esxi-X10SRH-CF-internal='TERM=xterm ssh -p 22 root@192.168.71.91'

The trick is the bold part: TERM=xterm (which you can also replace by export TERM=xterm; if you want future ssh sessions to use the same [wayback] TERM setting).

The reason is that the Mac defines the TERM variable as containing xterm-256 which is defined on the Mac itself, but ESXi has a hard time coping with it.

Some Mac OS and Xcode combinations had a problem with xterm-256 not being present ([WayBackmacos – Terminal strangeness after installing Xcode on Lion – Super User), but this isn’t the case on my system:

$ ls -alh `find /usr/share/terminfo | grep 'xterm-256color'`
-rw-r--r-- 1 root wheel 3.2K Jul 30 2016 /usr/share/terminfo/78/xterm-256color

On the Mac you really want to use xterm-256color as it looks way better than xterm-color or xterm: [WayBacklinux – What is the difference between xterm-color & xterm-256color? – Stack Overflow (thanks [WayBack] Chris Page!)

It seems I already did something similar on ESXi itself to get esxtop working: ESXi: when esxtop shows garbage. That was on the ESXi side and works as well for this problem too.

However, it is a bit harder to have a script run during ESXi boot time that sets this, so it is easier to fix this on the Mac side.

It works for all OS X and ESXi versions I’ve tested so far.

–jeroen

Posted in *nix, Apple, ESXi5.1, ESXi5.5, ESXi6, ESXi6.5, iMac, Mac, Mac OS X / OS X / MacOS, Mac OS X 10.4 Tiger, Mac OS X 10.5 Leopard, Mac OS X 10.6 Snow Leopard, Mac OS X 10.7 Lion, MacBook, MacBook Retina, MacBook-Air, MacBook-Pro, MacMini, macOS 10.12 Sierra, OS X 10.10 Yosemite, OS X 10.11 El Capitan, OS X 10.8 Mountain Lion, OS X 10.9 Mavericks, Power User, Virtualization, VMware, VMware ESXi | Leave a Comment »

{Updated} Linux server security checklist. #sysadmin 

Posted by jpluimers on 2019/03/11

Most tips are OK, but:

  1. for password related policies, please read these:
  2. If you do DNS, implement DNSSEC
  3. I think ipv6 is OK, but like ipv4 needs to be firewalled
  4. Be really careful with fail2ban and similar tools: they are easy ways to lock yourself out as well, for instance by someone doing a nice (D)DoS on you.

Tips: [WayBack40 Linux Server Hardening Security Tips [2017 edition] – nixCraft

Via:

–jeroen

Posted in *nix, *nix-tools, Encryption, Let's Encrypt (letsencrypt/certbot), Power User, Security | Leave a Comment »

sudo command doesn’t source /root/.bashrc – Unix & Linux Stack Exchange

Posted by jpluimers on 2019/03/08

TL;DR:

  • sudo -i is not an interactive logon to root
  • sudo -i bash is interactive and *does* execute /root/.bashrc

Source: [WayBack] sudo command doesn’t source /root/.bashrc – Unix & Linux Stack Exchange

–jeroen

Posted in *nix, *nix-tools, bash, Power User | Leave a Comment »

 
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