Tag Archives: centos

centos 5 – virtualbox guest additions fail to compile [solved]

Installing virtualbox guest additions was not really smooth. To ensure successful installation, make sure of the following: kernel-devel and kernel-headers must be installed for your current kernel version (reboot after installing) yum install *kernel-devel* *kernel-headers* make sure they match version returned by `uname -r` Note1: if you installed centos from iso, rpms are already on the iso under /CentOS folder (=> not need to download them and they will match installed kernel if you did not update it) Note2: to install these packages, do add GPG_KEY for centos5 packages via running rpm –import http://mirror.centos.org/centos/RPM-GPG-KEY-CentOS-5 although here again, GPG_KEY file is […]

can’t connect to X11 window server using ‘:0.0’ as the value of the DISPLAY variable [solved]

When running some dodgy software, I ended up on below error: can’t connect to X11 window server using ‘:0.0’ as the value of the DISPLAY variable I tried different values for $DISPLAY, with and without ip-address, no success. Command `xhost +` also returned error message: xhost: unable to open display “:0.0” Steps to solve this problem were as follow: Running `ps aux | grep X` returned following output: /usr/bin/Xorg :0 -br -verbose -nolisten tcp -audit 4 -auth /var/run/gdm/auth-for-gdm-NZACr6/database To get rid of -nolisten tcp option, which prevent remotely login on X server, option DisallowTCP must be set to false. Running […]

centos – change hostname

To change hostname permanently, edit /etc/sysconfig/network and update value for entry HOSTNAME sudo /etc/config/network After modification, file should look like this: # cat /etc/sysconfig/network NETWORKING=yes HOSTNAME=<hostname-goes-here> NTPSERVERARGS=iburst Change will be effective after reboot. To make it immediate, run as root hostname <hostname-goes-here> Command `hostname` allows to change hostname immediately, although modification is lost upon reboot. Therefore combination of /etc/sysconfig/network update & `hostname` command is the winning combination. sources http://www.electrictoolbox.com/changing-hostname-centos/  

installing sqldeveloper on centos

Steps to install sqldeveloper download rpm from oracle website or simply run `sudo apt-get install sqldeveloper-package` to install it from repository once sqldeveloper is installed, create connection, if test fails with error message “Network Adapter ….” this may simply mean: hostname is not in /etc/hosts and as such computer running oracle cannot be fetched port on oracle is blocked by firewall. To test this, simply run telnet <ip> <port> to check if port is opened If not open, edit vi /etc/sysconfig/iptables and add a line (same as for port 22) for oracle port (default port 1521) Then run service ipconfig […]

start/stop firewall in centos

In case `telnet <ip> <port>` returns some error message such as: Trying… telnet: Unable to connect to remote host: No route to host A quick way to rule firewall out of the picture is by disabling it entirely. Steps to do so: sudo services iptables save sudo services iptables stop If telnet manages to connect, you know it’s simply a matter of opening the port Trying… Connected to Don’t forget to restart firewall sudo services iptables start sources http://www.cyberciti.biz/faq/disable-linux-firewall-under-centos-rhel-fedora/