Question: How to prevent SSH connections from disconnecting due to inactivity when using MobaXterm client? In most production environment setups, SSH connections are configured to get disconnect after a short period of inactivity. This can sometimes be frustrating as you may have to keep on logging in frequently. Well, you can try the workaround outlined below. Change SSH connection settings in MobaXterm: 1. Go to the Settings menu: 2. Select Configuration: 3. In the popup … [Read more...] about How to prevent SSH connections from disconnecting due to inactivity when using MobaXterm
Solaris
Solaris Interview Questions – Inodes and the Filesystem Troubleshooting
1. Why 'du' and 'df' reports different values? - df describes disk usage. - du adds up the size all the files on a filesystem. They can report wildly different figures. One reason: Processes write to files. files can be deleted while processes are writing to files. So a file may be gone, but its inode may not be freed up. For example: # cat > bogus testing testing ^Z Stopped (user) # ls -i bogus 2921 bogus # fuser bogus bogus: 14947o # rm bogus # ls -i bogus bogus: No … [Read more...] about Solaris Interview Questions – Inodes and the Filesystem Troubleshooting
Solaris – Changing from iSCSI Static Discovery to SendTargets Discovery
This post is to provide steps from changing iSCSI Static Discovery to SendTargets Discovery. If zones are configured, zones need to be halted before changing the iSCSI discovery method then boot afterward. If zpool is configured, zpool needs to be exported before changing the iSCSI discovery method then import afterward. Below are high level steps: halt zones export -f zfs pools remove static disks disable static discovery service restart target discovery service import pools boot … [Read more...] about Solaris – Changing from iSCSI Static Discovery to SendTargets Discovery
Solaris 11.3 – Changing from iSCSI SendTargets Discovery to Static Discovery
Question: We have to set up a static configuration for an iSCSI device. It was added as dynamic but the specification calls for a static configuration. How to change iSCSI SendTargets Discovery to Static Discovery? 1. Halt the Solaris zones (if applicable). 2. Export the zfs pool: # zpool export {pool name} 3. Disable sendtargets discovery: # iscsiadm modify discovery --sendtargets disable 4. Enable static discovery: # iscsiadm modify discovery --static enable 5. Verify only … [Read more...] about Solaris 11.3 – Changing from iSCSI SendTargets Discovery to Static Discovery
Active FTP vs. Passive FTP
Introduction One of the most commonly seen questions when dealing with firewalls and other Internet connectivity issues is the difference between active and passive FTP(File Transfer Protocol) and how best to support either or both of them. Hopefully, the following text will help to clear up some of the confusion over how to support FTP in a firewalled environment. This post includes examples of both active and passive command line FTP sessions. These session examples should help make things … [Read more...] about Active FTP vs. Passive FTP
How to save sar reports longer than 7 days in Solaris
It might be necessary to save sar reports longer than 7 days. This post explains the steps to achieve this goal. The "sa2" is the script that is responsible for writing a summarized daily activity report. The /usr/lib/sa/sa2 has the following entries: #!/sbin/sh # Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T # All Rights Reserved # THIS IS UNPUBLISHED PROPRIETARY SOURCE CODE OF AT&T # The copyright notice above does not evidence any # actual or intended publication of such source … [Read more...] about How to save sar reports longer than 7 days in Solaris
How to set up cron for automatic data collection from the system activity reporter (SAR) in Solaris 10 and 11
This post outlines steps to set up a cron job for automatic data collection from system activity reporter (aka SAR). Prior to Solaris 10 1. Become the superuser. 2. Edit the following file: # vi /etc/init.d/perf 3. Uncomment the following lines (remove the # sign from the beginning of each line): #if [ -z "$_INIT_RUN_LEVEL" ]; then # set -- `/usr/bin/who -r` # _INIT_RUN_LEVEL="$7" # _INIT_RUN_NPREV="$8" # _INIT_PREV_LEVEL="$9" #fi # #if [ … [Read more...] about How to set up cron for automatic data collection from the system activity reporter (SAR) in Solaris 10 and 11
GUDS – A Script for Gathering Solaris Performance Data
Whats is GUDS? The GUDS script is a ksh script designed to collect the data needed to analyze performance issues. The script collects a specific set of files and runs a series of operating system utilities, the selection of which are based on the specified level. The duration, number of iterations, and other variables are provided to the script either as a set of command line arguments or are prompted for input in interactive mode. The collected data is then packaged and compressed in a … [Read more...] about GUDS – A Script for Gathering Solaris Performance Data
How to make telnet listen to a different port in Solaris
For security purpose, you may want telnet bind to a different port instead of the well-known port 23. It should be noted that changing port numbers of well-known services is also usually a bad idea. In general, services should either be left with their default ports or completely disabled. Changing the default port should only be opted as last option when you want to keep the service as enabled. Follow the steps below to change the telnet port from 23 to 24. 1. Check if nay other service … [Read more...] about How to make telnet listen to a different port in Solaris
How to Enable ssh/sshd Debugging for Solaris
This post will show how to put ssh (the client command) and sshd (the server daemon) into debug mode in order to troubleshoot authorization and connection problems. This debug output will be requested by Oracle/Sun technical support agents for ssh/sshd authorization and connection issues when opening service requests. Steps to Follow Configure the sshd daemon to run single threaded in debug mode. You have the choice of either: 1. stopping the active sshd on the system so that an sshd … [Read more...] about How to Enable ssh/sshd Debugging for Solaris