Tag: linux

How to get CORRECT memory usage for Linux

One of the most common mistakes made by Linux users, is to run free (Mem: line) or sar to get memory utilization.   The memory used fields include the space used by the OS to cache files and directory info cace,…

Lunix Core Files

To enable core file generation.. Configure core files to use the PID as a extension.   Set “kernel.core_uses_pid = 1” in /etc/sysctl.conf  and run “/sbin/sysctl -p /etc/sysctl.conf: or to add it temporarily run “/sbin/sysctl -w kernel.core_uses_pid=1” to change the running kernel.  …

Listing Full RPM Package Name

To get a full list RPM name, like the RPM file name use the Query Format option (–qf or –queryformat). This is useful in comparing 2 systems, seeing 32 bit and 64 bit packages and finding the RPMs. This lists…

Increasing Linux Ring Buffer Size

This doesn’t work on all drivers, but on the bnx2x and other it does.   In particular, if you are seeing packet drops this can help.   Use ethtool –g <interface> to see the buffer settings. # ethtool -g eth0 Ring…

Listing SSL cipher/protocols on remote host

To get a list of ciphers use nmap: nmap –script ssl-cert,ssl-enum-ciphers -p 443 www.example.com Starting Nmap 5.51 ( http://nmap.org ) at 2014-05-12 12:11 CDT Nmap scan report for www.example.com (10.10.10.10) Host is up (0.021s latency).%MCEPASTEBIN% PORT STATE SERVICE 443/tcp open…

Adding swap file to Linux

If there are no free partitions on a disk, you can create a swap file.   Here is how you add a 12GB file. # Check what you have for swap.   We have one 4GB  swap partition. server# swapon -s Filename                               …