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How to check I/O throughput and latency in Linux servers Hello, Recently our servers started behaving really strange. Suddenly they became very slow. Even I try with small commands such as ls , top I have got the output after a while but not with regular response. After analyzing running process and CPU utilization I went looking for I/O speed and that is where we found the issue. So checking I/O both troughput and latency is one of the important item while evaluating a Linux Server performance and you can use below commands to find. Throughput (I/O Streaming speed) dd if = /dev/zero of = /root/testfile bs = 1G count = 1 oflag = direct Latency dd if = /dev/zero of = /root/testfile bs = 512 count = 1000 oflag = direct Hope it will help you. Thank you.

How to check telnet for multiple IP at a time using Bash Hello, If you have multiple number of server and you would like check whether a particlur port open or not, generally you use telnet as below [ root@localhost ~ ] # telnet 192.168.56.102 22 Trying 192.168.56.102 .. . Connected to 192.168.56.102. Escape character is '^]' . SSH-2.0-OpenSSH_7.5 ^ ] telnet > q Connection closed. [ root@localhost ~ ] # Once connectivity got established, you have to give CTRL+] and q to exit from telnet session. For single IP this is fine but if you have multiple IPs then doing this for each IP is very annoying. But we can execute a perl command with inside a bash for loop with multiple IPs and after the threshold at alarm passed, it will exit automatically. for ip in "192.168.56.102" "localhost" do perl -e "alarm 10; exec @ARGV" "telnet " ${ip} " 22" done Here we dont have to pass any parameter to

How to check what SSL Ciphers are supported by your JVM Hello Team, If you ever wondered what are the SSL Ciphers supported by your appliaction which running on particular JVM, then you can find it with below program. Note: Make sure you are switched into user who is allowed to start your application. Go to /tmp directory and createa file named as Ciphers.java import java . util . Iterator ; import java . util . Map ; import java . util . TreeMap ; import javax . net . ssl . SSLServerSocketFactory ; public class Ciphers { public static void main ( String [ ] args ) throws Exception { SSLServerSocketFactory ssf = ( SSLServerSocketFactory ) SSLServerSocketFactory . getDefault ( ) ; String [ ] defaultCiphers = ssf . getDefaultCipherSuites ( ) ; String [ ] availableCiphers = ssf . getSupportedCipherSuites ( ) ; TreeMap ciphers = new TreeMap ( ) ; for ( int i = 0 ; i < a

How to: Oracle Sqlplus important flags for spool a table into CSV Hello, If you are trying to export a large table from a database via SQL Developer, it will take a lot of time. So to reduce the time and effort and you can log into or connect to remote Oracle DB via SQLPlus. And while importing the data, to get proper structuring to your data below flags will help you. set colsep , set headsep off set pagesize 0 set trimout on set feedback off set trimspool on set linesize 32767 set echo off SET TERMOUT For explanation of those flags, please read : https://docs.oracle.com/cd/B19306_01/server.102/b14357/ch12040.htm So if you are planning to export a table then whole .sql file should look like below set colsep , set headsep off set pagesize 0 set trimout on set feedback off set trimspool on set linesize 32767 set echo off spool 4802 . csv SELECT player || ',' || name || ',' || value FROM player WHERE value I

How to check TLS version support for a remote SSL URL by using openssl ? As recently many service providers are disabling the weak ciphers, TLSv1.2 becoming most trusted cipher at this moment compaing with TLSv1, TLSv1.1. If you want to know more about these protocols, please refer https://www.wolfssl.com/differences-between-ssl-and-tls-protocol-versions/ So if you are using services from any 3rd party/external service provider, then you want to verify the version of SSL protocol being used, then you can verify it with " openssl " # openssl s_client -connect URL:PORT -tls1_2 URL: Is the URL for which you want to check SSL supported protocol. Port: SSL port being used for that service. If your service providing supporting that protocol then you will get certificate chain in the output else you will get handshake errors in the output. Similarly you can verify support for other TLS protocols as well. TLSv1 # openssl s_client -connect URL:PORT -tl

If you are trying to list all the nodes connected to your puppet server, then you can use below command. # puppet cert list --all For example, [ root@puppetserver production ] # puppet cert list --all + "debian.mylabserver.com" ( SHA256 ) 63:17:8A:7D:E1:94:D4:BA:F8:7E:E5:09:4A:D4:A4:67:0A:62:8C:EF:AE:F3:4B:35:33:48:8C:46:55:90:0C:F6 + "puppetserver.mylabserver.com" ( SHA256 ) D5:9F:9C:10:22:92:53:7C:29:F4:A6:E6:84:A2:53:FE:74:B6:9F:87:B0:55:65:A4:D4:5F:B9:CD:09:71:0E:FA ( alt names: "DNS:puppet" , "DNS:puppetserver.mylabserver.com" ) Hope it helps. Thank you.