Basic Linux Commands (Tips and Tricks)
This post is to collect some basic linux commands I used while working on some Linux system:
- Upgrade System
- Basic Commands
- Iptable firewalls
- User and Group
- Change Interface IP Address
- Fold and Disk Commands
- Cron Job
- Create SSH Trust Relationship between two Linux Machines
- Find Big Files in Linux File System
- Find Out My Linux Distribution Name and Version
- Check Your Public IP Address from CLI
- PS command
- VI Command
- Check Hardware Info
- Install a software on Linux
- Use ssh key to encrypt / decrypt files
- AWS Amazon Linux Instance Commands
- Change Time Zone
- Add/Remove Route
- Remove Specific SSH Host Key
Upgrade System
For Ubuntu:
apt-get -y update & apt-get -y upgrade & apt-get -y dist-upgradefor CentOS
yum - y update & yum -y upgrade
man ： manual
ls ：List Directory Contentspwd ：print working directory
Or we can use the following command or script to stop the rules:
2.2. Changing Debian IPTABLES Rules To Survive Reboot
Change Interface IP Address
Fold and Disk Commands
There are 5 fields before the actual command:
field allowed values
----- --------------
minute 0-59
hour 0-23
day of month 1-31
month 1-12 (or names)
day of week 0-7 (0 or 7 is Sun, or use names)
Become root:
sudo su -
Change to user nsm:
su nsm
Go to the /home/nsm directory:
cd /home/nsm
Create the keys: (Path should be /home/nsm/.ssh/id_rsa. Leave the passphrase blank.)
Secure copy the public key to the other server as the admin user: (use admin password)
[email protected]% find . -type f -size +10000 -exec ls -lh {} \;
-rw-r--r-- 1 930 929 134M Jan 5 17:34 ./cf/packages/junos-11.4R6.6-domestic
-rw-r--r-- 1 root wheel 139M Sep 8 2011 ./cf/var/log/junos-srxsme-11.2R2.4-domestic.tgz
-rw-r----- 1 root wheel 4.9M Feb 11 17:12 ./cf/var/db/idpd/db/secdb_02.db
-rw-r----- 1 root wheel 6.7M Feb 11 17:13 ./cf/var/db/idpd/db/secdb_03.db
-rw-r----- 1 root wheel 64M Feb 11 17:13 ./cf/var/db/idpd/db/secdb_06.db
-rwxr-xr-x 1 admin 20 24M May 23 08:38 ./cf/var/db/idpd/nsm-download/SignatureUpdate.xml
.....
b. Checkpoint Firewall gateway:
[[email protected]]# find . -type f -size +50000k -exec ls -lh {} \; | awk '{ print $9 ": " $5 }'
./sysimg/CPwrapper/linux/CPEndpointSecurity/EndpointSecurityServer.bin: 145M
./sysimg/CPwrapper/linux/windows/SmartConsole.exe: 194M
./sysimg/CPwrapper/linux/CPrt/CPrt-R75.40-00.i386.rpm: 53M
./sysimg/CPwrapper/linux/CPportal/CPportal-R75.40-00.i386.rpm: 59M
./var/log/db: 336M
....
Find Out My Linux Distribution Name and Version
Basic Commands
man ： manual
ls ：List Directory Contents
pwd ：print working directory
cd ：change directory
mkdir ：Make directory
cp ：Copy
mv ：Move
find, locate, which and whereis : four commands to search file / folder in Linux
kill:
Linux Developing History
passwd ：Password
md5sum ：Compute and Check MD5 Message Digest
history ：History (Event) Record。
sudo ：(super user do)
touch ：Update the access and modification times of each FILE to the current time
chmod ：change file mode bits
chown ：change file owner and group
apt ：Advanced Package Tool
dd: Convert and Copy a file
[email protected]:~# dd if=/home/user/Downloads/debian.iso of=/dev/sdb1 bs=512M; sync
tar : Tape Archive
cal : Calendar
cat : Concatenation. Concatenate (join) two or more plain file and/or print contents of a file on standard output.
grep : searches the given file for lines containing a match to the given strings or words
ps : (Process)
service : command controls the Starting, Stopping or Restarting of a ‘service‘
df : disk usages of file system
du : disk usages
cmp : compare
wget : a free utility for non-interactive (i.e., can work in background) download of files from the Web
mount
gcc : is the in-built compiler for ‘c‘ language in Linux Environment.
g++ is the in-built compiler for ‘C++‘ , the first object oriented programming language.
Java is one of the world’s highly used programming language and is considered fast, secure, and reliable. Most of the the web based service of today runs on java.
Iptable firewalls
2.1 Delete IPtable firewall rules
[[email protected] ~]# /sbin/iptables -L -v -n
Chain INPUT (policy ACCEPT 0 packets, 0 bytes) pkts bytes target prot opt in out source destination 74M 53G RH-Firewall-1-INPUT all -- * * 0.0.0.0/0 0.0.0.0/0 Chain FORWARD (policy ACCEPT 0 packets, 0 bytes) pkts bytes target prot opt in out source destination 0 0 RH-Firewall-1-INPUT all -- * * 0.0.0.0/0 0.0.0.0/0 Chain OUTPUT (policy ACCEPT 18M packets, 1069M bytes) pkts bytes target prot opt in out source destination Chain RH-Firewall-1-INPUT (2 references) pkts bytes target prot opt in out source destination 5462 734K ACCEPT all -- lo * 0.0.0.0/0 0.0.0.0/0 46700 2228K ACCEPT icmp -- * * 0.0.0.0/0 0.0.0.0/0 icmp type 255 0 0 ACCEPT esp -- * * 0.0.0.0/0 0.0.0.0/0 0 0 ACCEPT ah -- * * 0.0.0.0/0 0.0.0.0/0 0 0 ACCEPT udp -- * * 0.0.0.0/0 224.0.0.251 udp dpt:5353 0 0 ACCEPT udp -- * * 0.0.0.0/0 0.0.0.0/0 udp dpt:631 719 34592 ACCEPT tcp -- * * 0.0.0.0/0 0.0.0.0/0 tcp dpt:631 63M 52G ACCEPT all -- * * 0.0.0.0/0 0.0.0.0/0 state RELATED,ESTABLISHED 3094 150K ACCEPT tcp -- * * 0.0.0.0/0 0.0.0.0/0 state NEW tcp dpt:22 10M 1029M REJECT all -- * * 0.0.0.0/0 0.0.0.0/0 reject-with icmp-host-prohibited [[email protected] ~]# /sbin/service iptables save Saving firewall rules to /etc/sysconfig/iptables: [ OK ] [[email protected] ~]# /sbin/service iptables stop Flushing firewall rules: [ OK ] Setting chains to policy ACCEPT: filter [ OK ] Unloading iptables modules: [ OK ] [[email protected] ~]# /sbin/iptables -L -v -n Chain INPUT (policy ACCEPT 0 packets, 0 bytes) pkts bytes target prot opt in out source destination Chain FORWARD (policy ACCEPT 0 packets, 0 bytes) pkts bytes target prot opt in out source destination Chain OUTPUT (policy ACCEPT 0 packets, 0 bytes) pkts bytes target prot opt in out source destination [[email protected] ~]# /sbin/service iptables start Flushing firewall rules: [ OK ] Setting chains to policy ACCEPT: filter [ OK ] Unloading iptables modules: [ OK ] Applying iptables firewall rules: [ OK ] Loading additional iptables modules: ip_conntrack_netbios_ns [ OK ] |
Or we can use the following command or script to stop the rules:
#!/bin/sh
echo "Saving current firewall rules at /root/current.firewall file..." iptables-save > /root/current.firewall echo "Stopping firewall and allowing everyone..." iptables -F iptables -X iptables -t nat -F iptables -t nat -X iptables -t mangle -F iptables -t mangle -X iptables -P INPUT ACCEPT iptables -P FORWARD ACCEPT iptables -P OUTPUT ACCEPT |
2.2. Changing Debian IPTABLES Rules To Survive Reboot
2.2.1. iptables scripts to enhance the rules at /usr/local/scripts/rc.iptables during a reboot
2.2.2. using iptables-restore and iptables-save to edit iptables rules
Linux1~# cat /etc/init.d/iptables
#!/bin/sh # IPTABLES_CONFIG=/usr/local/scripts/rc.iptables PATH=/usr/bin:/bin:/sbin:/usr/sbin:/usr/local/bin:/usr/local/sbin if [ ! -x /sbin/iptables ]; then exit 0 fi start() { if [ -f $IPTABLES_CONFIG ]; then iptables -F iptables -X echo $"Applying iptables firewall rules: " $IPTABLES_CONFIG echo touch /var/lock/subsys/iptables fi } stop() { iptables -P INPUT ACCEPT iptables -P OUTPUT ACCEPT iptables -P FORWARD ACCEPT iptables -F iptables -X echo rm -f /var/lock/subsys/iptables } case "$1" in start) start ;; stop) stop ;; restart) start ;; *) echo $"Usage: $0 {start|stop|restart}" exit 1 esac exit 0 Linux1~# vi /usr/local/scripts/rc.iptables Linux1~# /etc/init.d/iptables restart Linux1~#iptables -L -v -n | more |
2.2.2. using iptables-restore and iptables-save to edit iptables rules
iptables-save > /etc/iptables.test.rule
Add these lines to iptables file:
#!/bin/sh
/sbin/iptables-restore < /etc/iptables.up.rule
The iptables file under /etc/network/if-pre-up.d/ needs to be executable so change the permissions:
editor /etc/iptables.test.rule
iptables-restore < /etc/iptables.test.rule
iptables-save > /etc/iptables.up.rule
editor /etc/network/if-pre-up.d/iptables
Add these lines to iptables file:
#!/bin/sh
/sbin/iptables-restore < /etc/iptables.up.rule
The iptables file under /etc/network/if-pre-up.d/ needs to be executable so change the permissions:
chmod +x /etc/network/if-pre-up.d/iptables
Note: What I found is in some old Debian system, method b does not work. But method a works all the time.
User and Group
[[email protected] ~]# useradd test1
[[email protected] ~]# passwd test1 Changing password for user test1. New UNIX password: Retype new UNIX password: passwd: all authentication tokens updated successfully. [[email protected] ~]# usermod -a -G root test [[email protected] ~]# id test uid=501(test) gid=501(test) groups=501(test),0(root) context=root:system_r:unconfined_t:s0-s0:c0.c1023 [[email protected] ~]# groups root bin daemon sys adm disk wheel [[email protected] ~]# users root root [[email protected] ~]# groupadd network [[email protected] ~]# groups root bin daemon sys adm disk wheel [[email protected] ~]# cat /etc/group root:x:0:root,test,test1 test:x:501: test1:x:502: network:x:503: [[email protected] ~]# cat /etc/passwd root:x:0:0:root:/root:/bin/bash xfs:x:43:43:X Font Server:/etc/X11/fs:/sbin/nologin test1:x:502:502::/home/test1:/bin/bash |
Change Interface IP Address
- Temporary:
- ifconfig eth1 192.168.2.50 netmask 255.255.255.0 up
- Permanently
- RHEL / Red hat / Fedora / CentOS Linux eth1 config file - /etc/sysconfig/network-scripts/ifcfg-eth1
- Debian / Ubuntu Linux - /etc/network/interfaces
# /etc/init.d/network restartFold and Disk Commands
[[email protected] var]# rm -r dbbackup/ -f
[[email protected] var]# df -h Filesystem Size Used Avail Use% Mounted on /dev/hda3 7.6G 7.3G 0 100% / /dev/hda1 244M 12M 219M 6% /boot tmpfs 504M 0 504M 0% /dev/shm /dev/hdb1 197G 197G 0 100% /data [[email protected] var]# du -s 4779468 . |
Cron Job
[[email protected] ~]$ sudo su -
Password: [[email protected] ~]# crontab -l @daily scp -r find /var/netscreen/dbbackup/ -mtime -1 -type d -print [email protected]:/data @daily mv /root/CP_MGMT_*.tgz /data/backup/cp/ [[email protected] ~]# crontab -e [[email protected] ~]# |
There are 5 fields before the actual command:
field allowed values
----- --------------
minute 0-59
hour 0-23
day of month 1-31
month 1-12 (or names)
day of week 0-7 (0 or 7 is Sun, or use names)
Run a command once/week scheduled Saturday morning at 6am:
0 6 * * sat /path/to/command
or
0 6 * * 6 /path/to/command
Note: Website crontab.guru to write a proper cron job . https://wdt.io/ can provide cron job monitor service. For example, reboot httpd service every four hour:
Note: Website crontab.guru to write a proper cron job . https://wdt.io/ can provide cron job monitor service. For example, reboot httpd service every four hour:
[[email protected] log]# vi /etc/crontab
SHELL=/bin/bash
PATH=/sbin:/bin:/usr/sbin:/usr/bin
MAILTO=root
HOME=/
# For details see man 4 crontabs
# Example of job definition:
# .---------------- minute (0 - 59)
# | .------------- hour (0 - 23)
# | | .---------- day of month (1 - 31)
# | | | .------- month (1 - 12) OR jan,feb,mar,apr ...
# | | | | .---- day of week (0 - 6) (Sunday=0 or 7) OR sun,mon,tue,wed,thu,fri,sat
# | | | | |
# * * * * * user-name command to be executed
0 */4 * * * root sudo service httpd restart && curl -sm 30 k.wdt.io/[email protected]/reboot_httpd_4h?c=0_*/4_*_*_*
Create SSH Trust Relationship between two Linux Machines
Become root:0 */4 * * * root sudo service httpd restart && curl -sm 30 k.wdt.io/[email protected]/reboot_httpd_4h?c=0_*/4_*_*_*
sudo su -
Change to user nsm:
su nsm
Go to the /home/nsm directory:
cd /home/nsm
Create the keys: (Path should be /home/nsm/.ssh/id_rsa. Leave the passphrase blank.)
Secure copy the public key to the other server as the admin user: (use admin password)
- or Go to the remote server. The command below will add the key that is in temp1 file to the end of the authorized_keys file.
- Repeat steps 2-6 on deviceB. On deviceB, become root: (from user nsm, exit to root). Move the authorized_keys file that was copied to admin into nsm/.ssh:
- Change ownership of authorized_keys:
- At this point, you will be able to SSH between both servers without it asking for a password.
Find Big Files in Linux File System
- find . -type f -size +10000 -exec ls -lh {} \;
- find . -type f -size +50000k -exec ls -lh {} \; | awk '{ print $9 ": " $5 }'
- Find large files (>10M) in current folder find . -type f -size +10000k
a. Juniper Firewall
Sample output:[email protected]% find . -type f -size +10000 -exec ls -lh {} \;
-rw-r--r-- 1 930 929 134M Jan 5 17:34 ./cf/packages/junos-11.4R6.6-domestic
-rw-r--r-- 1 root wheel 139M Sep 8 2011 ./cf/var/log/junos-srxsme-11.2R2.4-domestic.tgz
-rw-r----- 1 root wheel 4.9M Feb 11 17:12 ./cf/var/db/idpd/db/secdb_02.db
-rw-r----- 1 root wheel 6.7M Feb 11 17:13 ./cf/var/db/idpd/db/secdb_03.db
-rw-r----- 1 root wheel 64M Feb 11 17:13 ./cf/var/db/idpd/db/secdb_06.db
-rwxr-xr-x 1 admin 20 24M May 23 08:38 ./cf/var/db/idpd/nsm-download/SignatureUpdate.xml
.....
b. Checkpoint Firewall gateway:
[[email protected]]# find . -type f -size +50000k -exec ls -lh {} \; | awk '{ print $9 ": " $5 }'
./sysimg/CPwrapper/linux/CPEndpointSecurity/EndpointSecurityServer.bin: 145M
./sysimg/CPwrapper/linux/windows/SmartConsole.exe: 194M
./sysimg/CPwrapper/linux/CPrt/CPrt-R75.40-00.i386.rpm: 53M
./sysimg/CPwrapper/linux/CPportal/CPportal-R75.40-00.i386.rpm: 59M
./var/log/db: 336M
....
Find Out My Linux Distribution Name and Version
[[email protected] ~]# cat /etc/*-release
Red Hat Enterprise Linux Server release 5.5 Beta (Tikanga) [[email protected] ~]# cat /proc/version Linux version 2.6.18-186.el5 ([email protected]) (gcc version 4.1.2 20080704 (Red Hat 4.1.2-46)) #1 SMP Wed Jan 27 18:14:15 EST 2010 Linux1:~# cat /proc/version Linux version 2.6.26-2-amd64 (Debian 2.6.26-27) ([email protected]) (gcc version 4.1.3 20080704 (prerelease) (Debian 4.1.2-25)) #1 SMP Wed Sep 21 03:36:44 UTC 2011 [[email protected] ~]# lsb_release -a LSB Version: :core-3.1-ia32:core-3.1-noarch:graphics-3.1-ia32:graphics-3.1-noarch Distributor ID: RedHatEnterpriseServer Description: Red Hat Enterprise Linux Server release 5.5 Beta (Tikanga) Release: 5.5 Codename: Tikanga Linux1:~# lsb_release -a No LSB modules are available. Distributor ID: Debian Description: Debian GNU/Linux 5.0.9 (lenny) Release: 5.0.9 Codename: lenny uname = (Unix Name), [[email protected] ~]# uname -a Linux Linux01p 2.6.18-186.el5 #1 SMP Wed Jan 27 18:14:15 EST 2010 i686 i686 i386 GNU/Linux [[email protected] ~]# uname -mrs Linux 2.6.18-186.el5 i686 |
Check Your Public IP Address from CLI
- curl -s checkip.dyndns.org|sed -e 's/.*Current IP Address: //' -e 's/<.*$//'
- curl icanhazip.com
- telnet www.checkmyip.com 80 | grep confidence | grep -Eo '([0-9]{1,3}\.){3}[0-9]{1,3}'
- wget -O - -q icanhazip.com
- wget http://ipinfo.io/ip -qO -
- curl ifconfig.me
PS command
Display the top 5 processes consuming most of the cpu:
$ cat /proc/cpuinfo
$ lscpu
For Memory :$ free -m (give you result by MB)
$ cat /proc/meminfo
For HDD:$ df -h (give you human readable result)
$ sudo fdisk -l
$ hdparm -i /dev/device (for example sda1, hda3...)
Install/Uninstall a software on Linux
For Red Hat/Fedora:
$ yum install firefox
If you are using Red Hat Enterprise Linux, it happens that the package you are looking for is in EPEL, so you can install that:
sudo rpm -Uvh http://download.fedora.redhat.com/pub/epel/5/i386/epel-release-5-4.noarch.rpm
and then you can:
yum install ncdu.
For Ubuntu ( run this as root ) :
# apt-get install firefox
For Debian/Ubuntu
# aptitude install firefox
Use ssh key to encrypt / decrypt files
[[email protected]]# ps aux --sort=-pcpu | head -5
USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND admin 3935 14.9 1.0 33032 10344 ? Ss 09:27 5:13 /bin/confd admin 3941 5.0 58.1 559724 556864 ? Ss 09:27 1:46 /bin/monitord admin 4215 1.4 3.6 251040 35412 ? Ssl 09:28 0:28 cpd admin 3937 0.7 0.2 26076 2808 ? Ssl 09:27 0:15 /bin/searchd |
VI Command
Cut and paste:
- Position the cursor where you want to begin cutting.
- Press v to select characters (or uppercase V to select whole lines).
- Move the cursor to the end of what you want to cut.
- Press d to cut (or y to copy).
- Move to where you would like to paste.
- Press P to paste before the cursor, or p to paste after.
Check Hardware Info
For CPU:$ cat /proc/cpuinfo
$ lscpu
For Memory :$ free -m (give you result by MB)
$ cat /proc/meminfo
For HDD:$ df -h (give you human readable result)
$ sudo fdisk -l
$ hdparm -i /dev/device (for example sda1, hda3...)
Install/Uninstall a software on Linux
For Red Hat/Fedora:
$ yum install firefox
If you are using Red Hat Enterprise Linux, it happens that the package you are looking for is in EPEL, so you can install that:
sudo rpm -Uvh http://download.fedora.redhat.com/pub/epel/5/i386/epel-release-5-4.noarch.rpm
and then you can:
yum install ncdu.
For Ubuntu ( run this as root ) :
# apt-get install firefox
For Debian/Ubuntu
# aptitude install firefox
Create a file:
echo ‘This is a sekret’ >/tmp/msg.txt
Export public key:
openssl rsa -in ~/private.pem -out /tmp/public.pub -outform PEM -pubout
Encrypt file with public key (anyone can have this key):
openssl rsautl -encrypt -inkey /tmp/public.pub -pubin -in /tmp/msg.txt -out /tmp/file.enc
Decrypt the file with private key (only you should have the private key):
openssl rsautl -decrypt -inkey ~/private.pem -in /tmp/file.enc -out /tmp/decrypted.txt
Check decoded message:
cat /tmp/decrypted.txt
sudo yum update -y
sudo yum install -y httpd24 php70 mysql56-server php70-mysqlnd
sudo service httpd star
sudo chkconfig httpd on
chkconfig --list httpd
curl http://localhost
sudo usermod -a -G apache ec2-user
groups
sudo chown -R ec2-user:apache /var/www
sudo chmod 2775 /var/www
find /var/www -type d -exec sudo chmod 2775 {} \;
find /var/www -type f -exec sudo chmod 0664 {} \;
echo "<?php phpinfo(); ?>" > /var/www/html/phpinfo.php
sudo yum list installed httpd24 php70 mysql56-server php70-mysqlnd
sudo service mysqld start
sudo chkconfig mysqld on
sudo service httpd restart
AWS Linux/CentOS/RHEL 6/5
Remove Specific SSH Host Key
Reference:
echo ‘This is a sekret’ >/tmp/msg.txt
Export public key:
openssl rsa -in ~/private.pem -out /tmp/public.pub -outform PEM -pubout
Encrypt file with public key (anyone can have this key):
openssl rsautl -encrypt -inkey /tmp/public.pub -pubin -in /tmp/msg.txt -out /tmp/file.enc
Decrypt the file with private key (only you should have the private key):
openssl rsautl -decrypt -inkey ~/private.pem -in /tmp/file.enc -out /tmp/decrypted.txt
Check decoded message:
cat /tmp/decrypted.txt
AWS Amazon Linux Instance Commands
sudo yum install -y httpd24 php70 mysql56-server php70-mysqlnd
sudo service httpd star
sudo chkconfig httpd on
chkconfig --list httpd
curl http://localhost
groups
sudo chown -R ec2-user:apache /var/www
sudo chmod 2775 /var/www
find /var/www -type d -exec sudo chmod 2775 {} \;
find /var/www -type f -exec sudo chmod 0664 {} \;
echo "<?php phpinfo(); ?>" > /var/www/html/phpinfo.php
sudo yum list installed httpd24 php70 mysql56-server php70-mysqlnd
sudo service mysqld start
sudo chkconfig mysqld on
sudo service httpd restart
Change Time Zone
Ubuntu
[email protected]:/var/log/apache2$ timedatectl list-timezones | grep Toronto America/Toronto [email protected]:/var/log/apache2$ sudo timedatectl set-timezone America/Toronto sudo: unable to resolve host ip-10-1-1-50 [email protected]:/var/log/apache2$ date Fri Sep 29 22:09:11 EDT 2017
[[email protected] ~]$ sudo su [[email protected] ec2-user]# mv /etc/localtime /root/localtime.old [[email protected] ec2-user]# ln -s /usr/share/zoneinfo/America/Toronto /etc/localtime [[email protected] ec2-user]# date Fri Sep 29 22:11:00 EDT 2017 [[email protected]0-0-50 ec2-user]#
Add/Remove Route
LinuxSvr:~# cat /etc/network/interfaces # This file describes the network interfaces available on your system # and how to activate them. For more information, see interfaces(5). # The loopback network interface auto lo iface lo inet loopback # The primary network interface allow-hotplug eth0 iface eth0 inet static address 10.9.2.10 netmask 255.255.255.0 network 10.9.2.0 broadcast 10.9.2.255 gateway 10.94.22.1 # dns-* options are implemented by the resolvconf package, if installed dns-nameservers 10.9.1.5 dns-search accounts.intern gdc.intern intern # #up route add -net 19.18.0.0/16 gw 10.9.2.3 #up route add -net 172.1.0.0/16 gw 10.9.2.3 #up route add -net 10.0.0.0/24 gw 10.9.2.3 mta:~#
Remove Specific SSH Host Key
If you have remote server system has changed, your ssh session might failed because ssh fingerprint is not matching what you have now for that host. To fix this issue, you will just need to remove existing host's fingerprint.
users-Mac-mini:~ user$ ssh -lroot 111.67.205.98
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!
Someone could be eavesdropping on you right now (man-in-the-middle attack)!
It is also possible that a host key has just been changed.
The fingerprint for the ECDSA key sent by the remote host is
SHA256:V9o8sh2Vxm56r+2q42minB4D88a8yTanlAPs4h/VAMY.
Please contact your system administrator.
Add correct host key in /Users/user/.ssh/known_hosts to get rid of this message.
Offending ECDSA key in /Users/user/.ssh/known_hosts:4
ECDSA host key for 111.67.205.98 has changed and you have requested strict checking.
Host key verification failed.
users-Mac-mini:~ user$ vim ~/.ssh/known_hosts
and hit
dd
then save it.
Reference:
- CentOS Basic Cofniguration
- Tutorial: Hosting a WordPress Blog with Amazon Linux
- Tutorial: Installing a LAMP Web Server on Amazon Linux
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