Linux IOPs benchmarking tool

December 11, 2017 Leave a comment

Notes from:
https://devopsideas.com/benchmarking-disk-iops-aws-vs-digitalocean/

Must have fio benchmarking tool installed along with libaio-devel package. Get fio from:
https://www.rpmfind.net/linux/rpm2html/search.php?query=fio&submit=Search+…

Random read/write (75%/25%) with 4G file:
# fio –randrepeat=1 –ioengine=libaio –direct=1 –gtod_reduce=1 –name=test –filename=test –bs=4k –iodepth=64 –size=4G –readwrite=randrw –rwmixread=75

read : io=3070.5MB, bw=132862KB/s, iops=33215 , runt= 23665msec
write: io=1025.6MB, bw=44375KB/s, iops=11093 , runt= 23665msec

Random read performance test:
# fio –randrepeat=1 –ioengine=libaio –direct=1 –gtod_reduce=1 –name=test –filename=test –bs=4k –iodepth=64 –size=4G –readwrite=randread

read : io=4096.0MB, bw=346522KB/s, iops=86630 , runt= 12104msec

Lot more options if you want to tailor your profile of io data for your test, refer to the man page for fio.

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Categories: Uncategorized

Oracle rebuild your indexes and how to find all of them

November 2, 2017 Leave a comment

Useful sql scripts to output your DDL for all index types:

— Rebuild index
select ‘alter index ‘||owner||’.’||index_name||’ rebuild ONLINE;’ from dba_indexes d where D.TABLE_NAME =‘PROVIDE_TABLE_NAME’ and D.OWNER=‘PROVIDE_OWNER’;

— Rebuild Partition index
select ‘alter index ‘||index_owner||’.’||index_name||’ rebuild partition ‘||partition_name||’ ONLINE;’ from dba_ind_partitions where INDEX_NAME=‘PROVIDE_INDEX_NAME’;

— Rebuild Sub Partition index
select ‘alter index ‘||index_owner||’.’||index_name||’ rebuild subpartition ‘||subpartition_name||’ ONLINE;’ from dba_ind_subpartitions where INDEX_NAME=‘PROVIDE_INDEX_NAME’;

Categories: Uncategorized

Kali Tools

October 19, 2017 Leave a comment

# Check for rootkits on local system
chkrootkit

 

Categories: Kali Linux, Uncategorized

portmap dead but subsys locked

October 19, 2017 Leave a comment

I have seen this issue and my feeling is it is a result of vulnerability scanners knocking the portmap service that handles the registration of systems for remote NFS, autofs.

Symptoms you may see:
Could not mount a user’s home directory:

su: warning: cannot change directory to /home/<user>: No such file or directory
# rpcinfo -p <nfs_server>
rpcinfo: can’t contact portmapper: RPC: Remote system error – Connection refused
# showmount -e
mount clntudp_create: RPC: Port mapper failure – RPC: Unable to receive

Resolution:
On NFS server if you see this error:

# service portmap status
portmap dead but subsys locked
# ll /var/lock/subsys/portmap    # If file exists, it has to be removed
# rm /var/lock/subsys/portmap
# service portmap restart
# rpcinfo -p
# service nfs restart    # Needs to be restarted to register with portmapper

Now, you should be able to run “rpcinfo -p <nfs_server>” from the NFS clients and mount the shares.

 

Categories: Linux, Redhat, Uncategorized

Kali SSH setup

October 17, 2017 Leave a comment

Move default keys to backup folder:
# cd /etc/ssh; mkdir backup_ssh; mv ssh_host_* backup_ssh
# dpkg-reconfigure openssh-server

Allow root to login
Edit /etc/ssh/sshd_config, add or change line to:
PermitRootLogin yes

Restart SSH
# service ssh stop; service ssh start; service ssh status

Kali Linux Updating Notes

October 17, 2017 Leave a comment

Run in a cron or in a shell script:
apt-get update && apt-get upgrade -y && apt-get dist-upgrade -y

apt-get install <package>
apt-get remove <package>
# List packages installed
dpkg -l
# list info about a package
apt-cache show <package>

# Repos where updates are retrieved
/etc/apt/sources.list

# Packages that speed up tools (may not be available for Kali 2.x)
apt-get install preload -y
# Increase privacy by removing temp files, cooks, caches, etc.
apt-get install bleachbit -y
# Remove unnecessary services; install Boot Up Manager
apt-get install bum -y
# Powers commands from keyboard
apt-get install gnome-do -y
# Search within apt system
apt-get install apt-file -y
# Deletion program that complies with govt standards
apt-get install scrub -y
# Capture screenshots of desktop
apt-get install shutter -y
# Print company name in header
apt-get install figlet -y
echo “figlet YOUR_COMPANY” >> ~/.bashrc

# Install TOR
apt-get install tor -y
# Edit /etc/proxychains.conf, change:
#strict_chain
dynamic_chain
socks5 127.0.0.1 9050

# Start TOR service
service tor start
proxychains iceweasel http://www.whatismyip.com

 

 

Categories: Kali Linux, Uncategorized

Samba CIFS mounts and securing user password

October 15, 2017 Leave a comment

Adding the code blocks below to /etc/rc.local:

mount.cifs //<host1>/share /<mount_point> -o ro,credentials=/root/.cifs.<host1>,remount

Option “remount” prevents double mounting of the same share.

File .cifs.<hostname> contains:

user=<user>
password=<password>
domain=<domain>

Categories: Linux, Redhat, Uncategorized