CT's Tech Notes

This note focuses on VM image and network manipulation at OpenStack environment Glance is the image service in OpenStack envrionment Create CentOS7 image glance image-create --name centos7-64 --file CentOS-7-x86_64-GenericCloud-1706.qcow2 --disk-format qcow2 --container-format bare --progres Default image directory /var/lib/glance/images/ You may want to convert raw disk to qcow2 qemu-img convert -f raw -O qcow2 vm-1.img vm-1.qcow2 Edit config parameter for Glance /etc/glance/glance-api.conf Restart Glance service to take effect of changes systemctl restart openstack-glance-api Neutron is network service at OpenStack environment Create network neutron net-create Custom-network --provider:network_type flat --provider:physical_network externalnet --router:external=True --shared neutron subnet-create --name external_subnet --enable_dhcp=False --allocation_pool start=192.168.1.10,end=192.168.1.250 --gateway=192.168.1.1 --dns 8.8.8.8 External-network 192.168.1.0/...

This note provides steps how to install kimchi(wok) for management of KVM virtualization Install Centos7 with Minimal installation Update system to up to date yum update -y Install KVM yum -y install qemu-kvm libvirt virt-install bridge-utils bind-utils virt-manager wget net-tools virt-viewer genisoimage epel-release Make sure KVM start upon reboot systemctl start libvirtd systemctl enable libvirtd Download Kimchi project installers wget https://github.com/kimchi-project/kimchi/releases/download/2.5.0/kimchi-2.5.0-0.el7.centos.noarch.rpm wget https://github.com/kimchi-project/kimchi/releases/download/2.5.0/wok-2.5.0-0.el7.centos.noarch.rpm wget http://kimchi-project.github.io/gingerbase/downloads/latest/ginger-base.el7.centos.noarch.rpm wget http://kimchi-project.github.io/ginger/downloads/latest/ginger.el7.centos.noarch.rpm Install RPMs yum localinstall * Start service systemctl enable wokd systemctl start wokd Allow firewall firewall-cmd --zone=public --pe...

This note provides steps how to install KVM and manage Guest OS with virsh. Install KVM yum -y install qemu-kvm libvirt virt-install bridge-utils bind-utils virt-manager wget net-tools virt-viewer genisoimage epel-release Install Guest OS from installer iso image virt-install --name VM-1 --ram 4096 --disk path=/testvm/VM-1.qcow2,size=40 --vcpus 2 --os-type linux --os-variant rhel6 --network bridge=br0 --graphics none --console pty,target_type=serial --cdrom /iso/CentOS-6.8-x86_64-bin-DVD1.iso --force Default directory for intalled VM /var/lib/libvirt/images/ Dump VM config into xml virsh dumpxml VM-1 > VM-1.xml Useful operation commands Create and start VM virsh define VM-1.xml virsh start VM-1 Shutdown VM virsh shutdown VM-1 Poweroff VM virsh destroy VM-1 Remove from VM list virsh undefine VM-1 Resize VM disk size qemu-img resize VM-1.img +60GB

This note provides how to setup self-signed certificate authority with OpenSSL. Generate CA Certificate openssl genrsa -des3 -out cloudtalents-ca.key 2048 openssl req -new -x509 -days 3650 -key cloudtalents-ca.key -out cloudtalents-ca.crt Sign Server Certificate with CA certificate that generated earlier Server key openssl genrsa -out cloudtalents-server.key 2048 Certificate request openssl req -new -out cloudtalents-server.csr -key cloudtalents-server.key Sign openssl x509 -req -in cloudtalents-server.csr -days 1825 -sha1 -CAcreateserial -CA cloudtalents-ca.crt -CAkey cloudtalents-ca.key -out cloudtalents-server.crt

This note provides how to setup private GIT repository server. Server setup Install git yum install git Create user useradd gitacc passwd gitacc Create ssh directory mkdir .ssh && chmod 700 .ssh touch .ssh/authorized_keys && chmod 600 .ssh/authorized_keys Create key to authenticate ssh-keygen -C "youremail@mailprovider.com" Create entries of public keys for allow users cat .ssh/id_rsa.pub | ssh user@123.45.56.78 "cat >> ~/.ssh/authorized_keys" Create project repository at server cd /home/gitacc mkdir "project" cd "project" git init --bare Client configuration Change to working directory cd "project" git init git add . git commit -m 'initial commit' git remote set-url origin gitacc@128.199.136.183:mt/mt-project.git git init git remote add origin gitacc@128.199.136.183:mt/mt-project.git Commit new file git add test.txt git commit -m 'created test.txt' git push origin...

This note provides how to setup pdns recursor for resloving DNS service. Install pdns recursor rpm -ivh pdns-recursor-3.7.3-1.el6.x86_64.rpm Create allow network db file cat > /etc/pdns-recursor/allow-network-db <<EOF #Default Allowed network 127.0.0.0/8 #Additional Allowed networks EOF Backup config file cp -a /etc/pdns-recursor/recursor.conf /etc/pdns-recursor/recursor.conf.orig Configure config file with allow network db list cat > /etc/pdns-recursor/recursor.conf <<EOF setuid=pdns-recursor setgid=pdns-recursor ################################# # allow-from-file If set, load allowed netmasks from this file # # allow-from-file allow-from-file=/etc/pdns-recursor/allow-network-db ################################# # any-to-tcp Answer ANY queries with tc=1, shunting to TCP # any-to-tcp means queries from clients that ask for ANY will get redirected to TCP. It has no influence on the outgoing transport of the Recursor # Default: no any-to-tcp=y...

Run qmail-qread to find out the id # /var/qmail/bin/qmail-qread Output 28 Mar 2014 01:01:47 GMT #93683 1793 &lt;#@[]&gt; remote @ We are interested #xxxx 28 Mar 2014 01:01:47 GMT  #93683  1793 &lt;#@[]&gt; remote @ Read the contents of an email in queue find /var/qmail/queue/ -name 93683 | xargs cat |less Report of qmail queue /var/qmail/bin/qmail-qstat Output messages in queue: 2 messages in queue but not yet preprocessed: 0