Linux Server Keeps Booting from Network PXE

Recently observed issues like the server keep booting from PXE, not from the OS virtual drive

Found the issue from BIOS console like OS having 3 disks but the order is not correct hence getting PXE boot problem

before fixing the problem boot drive is 0:0 is the Os virtual driver but in my case first drive 1:1 so only getting the issue

find out the correct order or correct OS disk SCSI id from VI layers and modify from boot login after resolving the problem OS is booted successfully.

Linux locate command not showing searching file but file is available in the system

I am searching nohup.out file in my server. in this case locate command not showing the file but file is available in the system. This is very simple think like very have update system database mean run updatedb.

[root@vm1 ~]# locate nohup.out
/test/nohup.out
/root/nohup.out

[root@vm1 ~]# ll /opt/VMware/bin/nohup.out
-rw——- 1 root root 43539 Jul 16 14:36 /opt/VMware/bin/nohup.out

[root@vm1 ~]# updatedb

[root@vm1 ~]# locate nohup.out
/test/nohup.out
/opt/VMware/bin/nohup.out
/root/nohup.out
[root@vm1 ~]#

SSH REMOTE HOST IDENTIFICATION HAS CHANGED -IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY

Problem

              “REMOTE HOST IDENTIFICATION HAS CHANGED”

 

[root@test ~]# ssh 10.10.10.110

@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@

@    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:Z8a5Z9sRzx38HRONwy/jrxt4GeeB8Bb6pGJNTH629bQ.

Please contact your system administrator.

Add correct host key in /root/.ssh/known_hosts to get rid of this message.

Offending ECDSA key in /root/.ssh/known_hosts:1

ECDSA host key for 10.10.10.11 has changed and you have requested strict checking.

Host key verification failed.

#cat /root/.ssh/known_hosts| grep 10.10.10.11

10.10.10.11 ecdsa-sha2-nistp256 AAAAE2VjZHNhLXNoYTItbmlzdHAyNTYAAAAIbmlzdHAyNTYAAABBBCsg9c8VsnZceixYiJ8pq

Reason SSH authentication key is changed in the destination server

Fix for this issue remove or comment older authentication key from source server in /root/.ssh/known_hosts file and try ssh it will work.

ssh_exchange_identification: Connection closed by remote host – Linux

[root@test]# ssh 10.10.10.11
ssh_exchange_identification: Connection closed by remote host

Reason for this issue

•    SSH connection is very slow b/w two clients so not able to exchange the ssh keys #time ssh user@ IP — >figure out why slow
•    /etc/hosts.deny file may be ssh is added – – > remove the entry
•    SSH key got corrupted – – > remove the key and exchange new one