Tag Archives: centos7

Dynamic MOTD on Centos7

Just few steps!

Install figlet package:

yum install figlet

1	yum install figlet

Create /etc/motd.sh script with this content:

#!/bin/sh
#
clear
figlet -f slant $(hostnamectl --pretty)
printf "\n"
printf "\t- %s\n\t- Kernel %s\n" "$(cat /etc/redhat-release)" "$(uname -r)"
printf "\n"



date=`date`
load=`cat /proc/loadavg | awk '{print $1}'`
root_usage=`df -h / | awk '/\// {print $(NF-1)}'`
memory_usage=`free -m | awk '/Mem:/ { total=$2 } /buffers\/cache/ { used=$3 } END { printf("%3.1f%%", used/total*100)}'`
swap_usage=`free -m | awk '/Swap/ { printf("%3.1f%%", "exit !$2;$3/$2*100") }'`
users=`users | wc -w`
time=`uptime | grep -ohe 'up .*' | sed 's/,/\ hours/g' | awk '{ printf $2" "$3 }'`
processes=`ps aux | wc -l`
ethup=$(ip -4 ad | grep 'state UP' | awk -F ":" '!/^[0-9]*: ?lo/ {print $2}')
ip=$(ip ad show dev $ethup |grep -v inet6 | grep inet|awk '{print $2}')

echo "System information as of: $date"
echo
printf "System load:\t%s\tIP Address:\t%s\n" $load $ip
printf "Memory usage:\t%s\tSystem uptime:\t%s\n" $memory_usage "$time"
printf "Usage on /:\t%s\tSwap usage:\t%s\n" $root_usage $swap_usage
printf "Local Users:\t%s\tProcesses:\t%s\n" $users $processes
echo

[ -f /etc/motd.tail ] && cat /etc/motd.tail || true

#!/bin/sh

clear

figlet -f slant $(hostnamectl --pretty)

printf "\n"

printf "\t- %s\n\t- Kernel %s\n" "$(cat /etc/redhat-release)" "$(uname -r)"

printf "\n"

date=`date`

load=`cat /proc/loadavg | awk '{print $1}'`

root_usage=`df -h / | awk '/\// {print $(NF-1)}'`

memory_usage=`free -m | awk '/Mem:/ { total=$2 } /buffers\/cache/ { used=$3 } END { printf("%3.1f%%", used/total*100)}'`

swap_usage=`free -m | awk '/Swap/ { printf("%3.1f%%", "exit !$2;$3/$2*100") }'`

users=`users | wc -w`

time=`uptime | grep -ohe 'up .*' | sed 's/,/\ hours/g' | awk '{ printf $2" "$3 }'`

processes=`ps aux | wc -l`

ethup=$(ip -4 ad | grep 'state UP' | awk -F ":" '!/^[0-9]*: ?lo/ {print $2}')

ip=$(ip ad show dev $ethup |grep -v inet6 | grep inet|awk '{print $2}')

echo "System information as of: $date"

echo

printf "System load:\t%s\tIP Address:\t%s\n" $load $ip

printf "Memory usage:\t%s\tSystem uptime:\t%s\n" $memory_usage "$time"

printf "Usage on /:\t%s\tSwap usage:\t%s\n" $root_usage $swap_usage

printf "Local Users:\t%s\tProcesses:\t%s\n" $users $processes

echo

[ -f /etc/motd.tail ] && cat /etc/motd.tail || true

Make the script executable:

chmod +x /etc/motd.sh

1	chmod +x /etc/motd.sh

Append this script to /etc/profile in order to be executed as last command once a user logs in:

echo "/etc/motd.sh" >> /etc/profile

1	echo "/etc/motd.sh" >> /etc/profile

Try and have fun! 🙂

If you are using Debian, here the other guide.

NFS – quick win

This is a very basic step-by-step guide to create a CentOS7 NFS server that shares a folder /nfsshare over 192.168.4.0/24 network. This share will be owned by apache and mountable on a CentOS web server.

Here the instructions how to create the server and how to setup the client.

NFS Server

Add this line in IPTABLES:

-A INPUT -s 192.168.4.0/24 -m comment --comment "NFS Network" -j ACCEPT

1	-A INPUT -s 192.168.4.0/24 -m comment --comment "NFS Network" -j ACCEPT

Run the following to create a share folder and setup NFS:

mkdir /nfsshare
yum install nfs-utils nfs-utils-lib -y
systemctl enable nfs-server
echo "/nfsshare 192.168.4.0/24(rw,sync,no_root_squash)" >> /etc/exports
sed -i 's/#Domain = local.domain.edu/Domain = nfsdomain.loc/' /etc/idmapd.conf
systemctl start rpcbind
systemctl start nfs-server

# Create apache user/group
# (NFS clients will read/write using this user so we want to have 
# the same set also on the server for an easier ownership management)
groupadd -g 48 apache
useradd -g 48 -u 48 apache

mkdir /nfsshare

yum install nfs-utils nfs-utils-lib -y

systemctl enable nfs-server

echo "/nfsshare 192.168.4.0/24(rw,sync,no_root_squash)" >> /etc/exports

sed -i 's/#Domain = local.domain.edu/Domain = nfsdomain.loc/' /etc/idmapd.conf

systemctl start rpcbind

systemctl start nfs-server

# Create apache user/group

# (NFS clients will read/write using this user so we want to have

# the same set also on the server for an easier ownership management)

groupadd -g 48 apache

useradd -g 48 -u 48 apache

NFS Client

e.g. assuming that NFS server’s IP is 192.168.4.1

Add this line in IPTABLES:

-A INPUT -s 192.168.4.0/24 -m comment --comment "NFS Network" -j ACCEPT

1	-A INPUT -s 192.168.4.0/24 -m comment --comment "NFS Network" -j ACCEPT

Then, run this:

yum install nfs-utils rpcbind

sed -i 's/#Domain = local.domain.edu/Domain = nfsdomain.loc/' /etc/idmapd.conf
echo "192.168.4.1 NFS01" >> /etc/hosts
mount -t nfs4 -o noatime,proto=tcp,actimeo=3,hard,intr,acl,_netdev NFS01:/nfsshare
tail -1 /proc/mounts >> /etc/fstab

yum install nfs-utils rpcbind

sed -i 's/#Domain = local.domain.edu/Domain = nfsdomain.loc/' /etc/idmapd.conf

echo "192.168.4.1 NFS01" >> /etc/hosts

mount -t nfs4 -o noatime,proto=tcp,actimeo=3,hard,intr,acl,_netdev NFS01:/nfsshare

tail -1 /proc/mounts >> /etc/fstab

NOTE: we are hardly mapping the NFS server’s IP in /etc/hosts to make easier to recognise the mount (in case of multiple mounts).

If you are facing the issue where you mount /nfsshare and you see the owner of the files and folders showing as nobody:nobody, it could be related to rpcidmapd and DNS. To fix this, try to update /etc/hosts on the Client with <hostname>.nfsdomain.loc

# ============= #
# Ubuntu Notes  #
# ============= #

!! Same users on Server and Client - for the exported partition !!

SERVER
apt-get install nfs-kernel-server

vim /etc/exports
/var/www/vhosts		192.168.3.*(rw,sync,no_root_squash,no_subtree_check)

service nfs-kernel-server restart
exportfs -a


CLIENT
apt-get install nfs-common
mount -t nfs4 192.168.3.1:/var/www/vhosts /var/www/vhosts/

!! CHECK the output of cat /proc/mounts and you can get the correct rsize/wsize. If the firewall/network can handle, keep this value as big as possible:

e.g.

noatime,proto=tcp,actimeo=3,hard,intr,acl,_netdev,rsize=1048576,wsize=1048576

vim /etc/fstab
192.168.3.1:/var/www/vhosts   /var/www/vhosts nfs4    noatime,actimeo=3,hard,intr,acl,_netdev,rsize=32768,wsize=32768 0 0

# ============= #

# Ubuntu Notes #

# ============= #

!! Same users on Server and Client - for the exported partition !!

SERVER

apt-get install nfs-kernel-server

vim /etc/exports

/var/www/vhosts 192.168.3.*(rw,sync,no_root_squash,no_subtree_check)

service nfs-kernel-server restart

exportfs -a

CLIENT

apt-get install nfs-common

mount -t nfs4 192.168.3.1:/var/www/vhosts /var/www/vhosts/

!! CHECK the output of cat /proc/mounts and you can get the correct rsize/wsize. If the firewall/network can handle, keep this value as big as possible:

e.g.

noatime,proto=tcp,actimeo=3,hard,intr,acl,_netdev,rsize=1048576,wsize=1048576

vim /etc/fstab

192.168.3.1:/var/www/vhosts /var/www/vhosts nfs4 noatime,actimeo=3,hard,intr,acl,_netdev,rsize=32768,wsize=32768 0 0

Fullstatus Apache 2.4 Centos7

Apache on CentOS 7 doesn’t come with any configuration for enabling /server-status
The module does come by default though, so to get this going, all you need to do is:

$ cat >> /etc/httpd/conf.modules.d/01-status.conf << EOF
<Location /server-status>
SetHandler server-status
Require local
</Location>
EOF

$ systemctl reload httpd
$ apachectl fullstatus

$ cat >> /etc/httpd/conf.modules.d/01-status.conf << EOF

SetHandler server-status

Require local

</Location>

EOF

$ systemctl reload httpd

$ apachectl fullstatus

Disable firewalld – Centos 7

Install iptables and remove firewalld

yum install -y iptables-services

systemctl stop firewalld
systemctl mask firewalld

systemctl enable iptables
systemctl start iptables

yum install -y iptables-services

systemctl stop firewalld

systemctl mask firewalld

systemctl enable iptables

systemctl start iptables

My notepad

Chris' IT notes…