pv issue

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Error: kernel rejection i/o to offline device

How to configure ssh with both key and password?


Redhat Enterprise Linux 6, 7


How to enable dual authentication in ssh?
Hoe to force the users to use both key and password?
How to enable both key and password in ssh?


Add following directive to sshd_config


RequiredAuthentications2 publickey,password

To disable for particular user


Match User oracle
RequiredAuthentications2 password

Add following directive to sshd_config


AuthenticationMethods publickey,password

Root Cause

By default sshd will not force dual authentication.

Product(s) Red Hat Enterprise Linux

Category Configure

Tags authentication configuration rhel ssh troubleshooting

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I have prepared a script for monitoring the Current CPU, DISK, Memory utilization and previous day sar report in email. Email will be triggered automatically every day at 6:30 PM EST. Below is the script for your reference :

a=$(date | cut -f2-3 -d” “)
cd /var/log/sa
b=$(ls -l | grep sa | grep “$(echo $a)” | awk ‘{print $9}’)
sar -r -f $(echo $b) > /tmp/sar24.txt
zip /tmp/performance_reports.zip /tmp/cpu_utilization.txt /tmp/memory_utilization.txt /tmp/disk_utilization.txt /tmp/network_utilization.txt /tmp/sar24.txt
mailx -s ‘hostname’ -a /tmp/performance_reports.zip gkrishna6@csc.com nodonnell@csc.com > /tmp/cpu_utilization.txt
##Memory Utilization
02 * * * * free -g | sed -n ‘1!p’ | sed -n ‘2!p’ >> /tmp/memory_utilization.txt
03 * * * * sar -d 2 1 | sed -n ‘1!p’ >> /tmp/disk_utilization.txt
##Network Interfaces
04 18 * * * sar -n DEV | sed -n ‘1!p’ >> /tmp/network_utilization.txt
##Send Mail
30 18 * * * cd /tmp/ && ./utilization.sh

Setup NTP

# cd /etc/ntp

edit the ntpservers file and add your ntpservers


Start the ntp service and check ntp
# service ntpd start
# ntpq -p

remote refid st t when poll reach delay offset jitter
*mail01.tjgroup. 2 u 32 64 37 37.598 -465.66 2.783
ns1.pulsation.f 3 u 23 64 37 28.774 -478.17 0.862
+enigma.wiredgoa 2 u 30 64 37 161.413 -475.88 1.307
LOCAL(0) LOCAL(0) 10 l 29 64 37 0.000 0.000 0.004

Start the ntp service on reboot
# chkconfig ntpd –list
ntpd 0:off 1:off 2:off 3:off 4:off 5:off 6:off

# chkconfig –levels 2345 ntpd on
# chkconfig ntpd –list
ntpd 0:off 1:off 2:on 3:on 4:on 5:on 6:off