/ - rtt - IT Resource

  • systemd management using systemctl and journalctl to check systemd logs


    systemd is like the service manager for your Centos and other modern Linux distributions (including Debian/Mint/Ubuntu) allows you to enable services, stop them, restart them, check their status and even reboot your system. The key commands or arguments you will use with systemctl are the following: Unit Commands:   list-units [PATTERN...]         List loaded units &nbs........
  • Firefox An error occurred during a connection to some-ip-or-domain. SSL peer reports incorrect Message Authentication Code. Error code: SSL_ERROR_BAD_MAC_ALERT Solution


    An error occurred during a connection to some-ip-or-domain. SSL peer reports incorrect Message Authentication Code. Error code: SSL_ERROR_BAD_MAC_ALERT     The page you are trying to view cannot be shown because the authenticity of the received data could not be verified.     Please contact the website owners to inform them of this problem. **Solution** Go to about:config........
  • Linux bash shell doesn't show username, hostname or current path fix solution


    Usually this is because when you created your user you added a user but didn't create their home directory and/or for some reason your .bashrc and .bash_profile in ~ (home) is broken/missing. In your home just create the following files with the following content to solve it: .bashrc and .bash_profile. To apply it just relogin/start a new bash session # .bash_profile # Get the aliases and funct........
  • VMWare ESXi 6.7 SSH/PowerShell CLI Commands


    [root@localhost:~] BootModuleConfig.sh          echo                         host-ind                     nfcd                   ........
  • VMWare 6.7 VCSA VSphere ESXi Management SSO Install Guide on Linux using the CLI


    #mount the VCSA DVD mount /dev/sr0 /mnt/cd #alternatively you could mount the iso directly mount -o loop vcsa.iso /your/mount/path #for this purpose we are using the CLI installer on Linux cd /mnt/cd/vcsa-cli-installer/lin64 #no it's not going to be that easy you can't just run vcsa-deploy like that you need to use a template or configured .json file ./vcsa-deploy Usage: vcsa-deploy [-h] [--version] [--supported-deploymen........
  • named[1525]: error (broken trust chain) resolving 'min-api.cryptocompare.com/A/IN': 173.245.58.78#53 solution


    So you restarted your router/dhcpd server or for some other reason you wonder why DHCP is not working on any of your clients?  You go and check that named is in fact running fine. But then you check /var/log/messages and see this error for everything hostname: named[1525]: error (broken trust chain) resolving 'min-api.cryptocompare.com/A/IN': 173.245.58.78#53 I've only ever seen this when the time on the server was off.  It........
  • sudo: unable to resolve host


    sudo: unable to resolve host yourhostname No clue why sudo is doing that when running. Solution   Check /etc/hosts You will probably find that it doesn't contain "yourhostname" for 127.0.0.1 Just update the hostname or add a field for your hostname like this: 127.0.0.1 yourhostname  ........
  • Linux How To Clone One System Harddrive to another remote system


    The easiest way is to use SSH and DD or a combination of netcat.  SSH will be a little slower due to encryption but is the most secure way (on two older systems the average clone speed is about 40-50MB/s).  This is also OS independent as it doesn't matter what the source OS is because you are literallly cloning the drive so you retain the partition table and settings.   Clone HDD using SSH and DD........
  • Linux last command show login by IP instead of hostname


    In the "last" command in Linux by default it will show the information with the hostname (not very useful at all especially since it normally truncates long hostnames). To get last to show the IP address use this: last -i The -i makes it show the numeric IP instead of hostname.........
  • Centos 7 How To Change Hostname


    Some guides still use the old Centos 6 style (do not use /etc/sysconfig/network). In Centos 7 the file is /etc/hostname echo "HOSTNAME=yourhostname.com" > /etc/hostname........
  • USB 3.0 External HDD Enclosure Seagate UAS problems - [sdd] tag#1 CDB: Write(16) 8a 00 00 00 00 01 70 04 08 68 00 00 00 08 00 00


      This is a 8TB Seagate external USB 3.0 device apparently newer kernels use a module called "UAS" instead of "USB Storage" which causes issues as a lot of devices are not properly supported in UAS mode by the kernel driver.  The solution some say is to disable UAS specifically for your USB device but I'd rather just disable UAS altogether.   Solution blacklist UAS: *do not do this it does not work and just causes your USB 3.0........
  • mdadm frozen and doesn't realize array is dead/missing failed due to unplugged drives


    This was a surprising bug but I unplugged all drives for an array md127.  At first it was just 1 drive and mdadm seemed to notice this.  I unplugged the second drive taking the array offline but mdadm did not realize it was offline and still showed a non-existent disk as being part of it.  This created problems trying to unmount it or even to stop this array with mdadm freezing.  As for how to fix it I can only think of making sure you are not in a mounted path of........
  • Apache Log Error Message when starting


    Usage: geoiplookup [-h] [-?] [-d custom_dir] [-f custom_file] [-v] [-i] [-l] <ipaddress|hostname> Usage: geoiplookup [-h] [-?] [-d custom_dir] [-f custom_file] [-v] [-i] [-l] <ipaddress|hostname> grep: Address: No such file or directory grep: not: No such file or directory grep: found: No such file or directory sh: -c: line 1: syntax error near unexpected token `|' sh: -c: line 1: `|cut -d ',' -f 2'  ........
  • Cannot Read License File cPanel Solution


    This can happen because port 80 is not open, or your license has expired and/or your IP is out of date and also if the license server itself from cPanel is having issues. In most cases as long as you have a valid license the following command will solve it:  /usr/local/cpanel/cpkeyclt Updating cPanel license...Done. Update succeeded. Building global cache for cpanel...Done   Cannot........
  • Samsung Printer Password Login to change settings CLP


    First of all to find your IP you can hold the "X" button for a few seconds and it will print out the DHCP IP. Another way to find the IP that I prefer is to login to your router or switch and find a hostname that says something like "SEC001599CD2948" which will be your Samsung printer (at least for the C3xx or C4xx series of Samsung printers). The login and password for Samsung Syncthru Webservice:........
  • Ubuntu Linux Slow/Delayed SSH ping response Solution


    I've only ever seen this in Ubuntu for some reason and it is because of the /etc/nsswitch.conf settings. So the issue is that if the hostname's reverse DNS cannot be found that you need to go back to DNS which was not the default in this nsswitch.conf file for some strange reason. Edit /etc/nsswitch.conf and replace your "hosts" line with this: #hosts:          files dns mdns4_minimal [NOTFOUND=return] mdns........
  • Asterisk iptables block bruteforce attacks howto with fail2ban


    yum -y install fail2ban vi /etc/fail2ban/jail.conf [asterisk-tcp] enabled  = true filter   = asterisk action   = iptables-multiport[name=asterisk-tcp, port="5060,5061", protocol=tcp]            sendmail-whois[name=Asterisk, dest=you@example.com, sender=fail2ban@example.com] logpath  = /var/log/asterisk/messages maxret........
  • CPanel Log File Locations for access_log,error_log, mysql


    All Errors (CPanel does not report by domain, but puts everything in a single log which I think is a bit silly and annoying): /usr/local/apache/logs/error_log Access_Logs They are found within the home directory of the site user eg.: /home/admin/access-logs/yoursite.com MySQL Logs  /var/lib/mysql/yourhostname.err........
  • Apache SNI is not needed what is the issue?


    I read this article and still don't understand the issue. If I understand correctly the client negotiates after the first SSL connection and then gets the correct hostname and thus correct certificate. http://wiki.apache.org/httpd/NameBasedSSLVHostsWithSNI To their credit I know I'm not using SNI becuase I get this message in the Apache log :) [warn] Init: You should not use name-based virtual hosts in conjunction with SSL!! B........
  • GoDaddy How To Register and Create/Use Your Own DNS Name Servers


    http://support.godaddy.com/help/article/668/registering-your-own-nameservershosts?pc_split_value=1 Log in to your GoDaddy Account. Click on "My Account" at the top left. Click on "Domains". Click on the "Launch" button for the domain you want to create the nameservers for. Find........
  • stat=Deferred: 451-Non-existent domain mailserver.com


    Jul 11 15:20:58 tor sendmail[9617]: r6AKjOD07: to= mailserver.com was the hostname of the server, sendmail sends this by default and many mailservers will reject mail to a hostname that does not resolve or exist. The easiest way is just to change the hostname and make sure it does resolve to something. I read there is a way in sendmail.mc to manually set a hostname but I never got it working: vi /etc/mail/sendmail.mc define(`confDOMAIN........
  • Directadmin Log File Locations


    This is a handy link and list of all the relevant Directadmin log files and related servers.   http://help.directadmin.com/item.php?id=11   DirectAdmin: /var/log/directadmin/error.log /var/log/directadmin/errortaskq.log /var/log/directadmin/system.log /var/log/directadmin/security.log Apache:........
  • Directadmin Solution "This is e-mail notification to warn you that your hostname is setup improperly on your system."


    This is e-mail notification to warn you that your hostname is setup improperly on your system. This is an annoying message and bug with Directadmin, my hostname is set correctly, why does it complain? To get of this message just run this command: /usr/local/directadmin/scripts/hostname.sh yourhostname.com........
  • email server messsages rejected without reverse DNS DNS check failure Client host rejected: cannot find your reverse hostname Cannot resolve PTR record


    Basically you should always be 100% sure that whatever IP your mail server sends out with has reverse DNS/PTR records.  Remember that unless you own your IPs then you won't be able to set your own reverse DNS.  Even if you were to create a reverse PTR record on your DNS servers it will be ignored. Reverse DNS is queried to pre-assigned DNS servers of your ISP, so therefore you'll need to contact your ISP/Colo/Hosting provider to do a reverse DNS entry. If you don't have........
  • FUSE/Curlftpfs mount ftp account as drive partition in Linux


    This is a great way to use your ftp server space, for example on your web hosting account (although I believe many hosts don't allow storage like this), but if you have a VPS/Dedicated Server etc.., this would be perfect.  Imagine how easy it is to work with an ftp account that you can just mount as a normal partition or directory in Linux, it would be great for backups etc..   Name curlftpfs - mount a ftp host as a local directory Synopsis........
  • Use rcconf to edit startup/init.d/init scripts on Debian/Ubuntu based distributions


    I've never understood how to enable and disable services for different run levels in Debian based distros, it's just weird, annoying and doesn't make sense.  I much prefer chkconfig from RHEL. Just install the package called 'rcconf' and be done with it.  rcconf makes things easy for you. apt-get install rcconf Reading package lists... Done Building dependency tree        Reading state information... Done........
  • CPanel Solution for Error Missing HOST Config Line in /etc/wwwacct.conf, please reconfigure with Edit Setup.


    Edit /etc/wwwacct.conf Then add/edit the HOST line to add your hostname. eg: HOST yourcpanelserver.com........
  • Create/Enable SSL Certificates for Apache on Linux/Unix Systems eg. Redhat,Centos,Debian


    Shortcut/Easiest Way To Create A Self-Signed Key: openssl req -new -x509 -nodes -days 1530 -out server.crt -keyout server.key Using the above, you instantly create a self-signed certificate valid for 1530 days and you can simply skip to step #5.) below. If You Need a Real SSL Certificate (eg. Equifax/Openssl) then you need to create a CSR request (you'll need to follow Steps 1.) and 2.) in order to create the CSR.  You then upload the CSR Certi........
  • Configuring OCFS2 Clustered File System on Debian Based Linux including Ubuntu and Kubuntu


    There's a lot of information and guides on OCFS2 for RHEL and Centos Linux but the package setup and configuration is slightly different and this has thrown some people off. Installing OC2FS You should install the following packages to get started: apt-get install ocfs2-tools ocfs2console Configure OC2FS In RHEL/Centos the main configuration file is located in /etc/sysconfig/o2cb However in Debian based Linux it is located........
  • Viewing and Connecting to an SMB Samba Share on Windows/Linux/Unix


    This will give you the basic info needed to browse and connect to Samba shares from the command line.  From the GUI of Gnome or KDE etc, it is pretty standard and straight forward.  However, I've found very little guides on how to do it from the command line and if you're like me, a nerd who prefers command line for its simplicity and for remote use, this is the way to go. First get a list of all the Samba/SMB shares on the target. smbclient -L hostname........
  • ENOM Major Outage


    At this time we can't resolve Enom's website and all DNS requests to their 4 primary name servers are failing, although the hostnames themselves still resolve:    Name Server: DNS1.NAME-SERVICES.COM    Name Server: DNS2.NAME-SERVICES.COM    Name Server: DNS3.NAME-SERVICES.COM    Name Server: DNS4.NAME-SERVICES.COM    Name Server: DNS5.NAME-SERVICES.COM You would really think Enom, bein........
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