Willing wheels

Here is a very nice package to listen to tcp ports: sudo apt-get install tcpflow To activate it, run: sudo tcpflow -i any -C -e port XXXX Options may vary based on version of the tool. tcpflow -h for more details sources http://superuser.com/questions/23180/whats-the-easiest-way-to-sniff-tcp-traffic-data-on-linux

To log queries on oracle, proceed as follow: login as system (`sqlplus system`) check audit status show parameter AUDIT_TRAIL; // if NONE => no audit activated activate audit ALTER SYSTEM SET AUDIT_TRAIL=DB SCOPE=SPFILE; restart db for parameter to take effect /etc/ini.d/oracle-xe restart from this point forward, activate audit on specific tables and/or actions and/or users using the AUDIT XXX statement, as `system`, run: AUDIT SELECT on userlambda.tablename // audit/log all SELECT queries on all tables db for user userlambda All audit entries are stored under sys.AUD$ table (login as system to access it). sources http://docs.oracle.com/cd/E11882_01/network.112/e16543/auditing.htm#DBSEG395 http://docs.oracle.com/cd/E11882_01/server.112/e41084/statements_4007.htm#SQLRF53716 http://www.dba-oracle.com/t_audit_sql_select_statements.htm

When trying to get sqlplus client running, following error was generated: sqlplus: error while loading shared libraries: libsqlplus.so: cannot open shared object file: No such file or directory This happens because environment variable LD_LIBRARY_PATH was empty. Make it point to ./lib folder where sqlplus client was extracted and this should solve the problem. In my case, oracle sqlplus client was generated under /opt/oracle LD_LIBRARY_PATH=/opt/oracle/bin export LD_LIBRARY_PATH And voila! sources http://betterlogic.com/roger/2010/11/how-to-install-sql-plus-in-linux/

There is a great tool to identify files being access: inotifywait steps make sure inotify package is installed sudo apt-get install inotify-tools simply run inotifywait -m -r –format ‘%:e %f’ . all files being accessed will be displayed Additional filtering and output formatting options are available, `man inotifywait` for more information. Note that inotifywatch is also available, no monitor files for a given timeperiod. examples //1. listen to all events on all files (recursively) within current directory with output of type “EVENT_TYPE file_name” inotifywait -m -r –format ‘%:e %f’ . // 2. listen to event MODIFY (i.e. writing content) on […]

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 […]

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 […]

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/  

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 […]

In case `telnet <ip> <port>` returns some error message such as: Trying 192.168.1.13… 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 192.168.1.13… Connected to 192.168.1.13. Don’t forget to restart firewall sudo services iptables start sources http://www.cyberciti.biz/faq/disable-linux-firewall-under-centos-rhel-fedora/

This error occurred when I was installing oracle 11g R2 express. Post installing rpm file, next action is to run ‘sudo /etc/init.d/oracle-xe configure’. Following error message is displayed: Database Configuration failed. Look into /u01/app/oracle/product/11.2.0/xe/config/log for details When looking at log files, obscure messages were printed: Create controlfile reuse set database “XE” * ERROR at line 1: ORA-01034: ORACLE not available Process ID: 0 Session ID: 0 Serial number: 0 BEGIN dbms_backup_restore.zerodbid(0); END; * ERROR at line 1: ORA-01034: ORACLE not available Process ID: 0 Session ID: 0 Serial number: 0 ORA-01034: ORACLE not available ORA-27101: shared memory realm does not […]