How to compare a remote host fingerprint to the fingerprint of a different host?

Hunter

6/13/23, 10:39 PM

I have two ways of accessing my remote host ssh server:

using its local IP addres
using its public IP address

Yesterday, I reinstalled my SSH server on the remote host and I updated my known hosts file for the local IP address. I am now off of my local network and trying to connect to my server using its public IP address and I realized I forgot to update my known hosts file after reinstalling the SSH service. This is giving me the common error below.

@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@    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
MD5:FINGERPRINT.
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:25
ECDSA host key for [PUBLIC IP]:PORT has changed and you have requested strict checking.
Host key verification failed.

I'm 99% sure this is because I changed the SSH server, however, if I wanted to double check and verify, how would I do this?

My question is

How can I verify the new fingerprint of the remote host against the fingerprint saved for the local IP address of the server?

What I've Done

I ran the following command: ssh-keygen -lv -f ~/.ssh/known_hosts and found the SHA256 fingerprint saved for the local ip address of my server.
I compared this to the SHA256 fingerprint being sent to me from my remote host, and they appear to be identical.

How can I be 100% sure? Did I do this properly?

0 + 0

ssh

A.B

6/14/23, 7:42 AM

What you also did: cross-post this question to https://superuser.com/questions/1704774/how-to-compare-a-remote-host-fingerprint-to-the-fingerprint-of-a-different-host . See this meta Q/A about this: https://meta.stackexchange.com/questions/64068/is-cross-posting-a-question-on-multiple-stack-exchange-sites-permitted-if-the-qu/64069#64069

Elon Musk

I sit in a Tesla and translated this thread with Ai:

EN: How to compare a remote host fingerprint to the fingerprint of a different host?

TH: จะเปรียบเทียบลายนิ้วมือของโฮสต์ระยะไกลกับลายนิ้วมือของโฮสต์อื่นได้อย่างไร

RO: Cum se compară o amprentă a unei gazde la distanță cu amprenta unei alte gazde?

RU: Как сравнить отпечаток пальца удаленного хоста с отпечатком другого хоста?

VI: Làm cách nào để so sánh dấu vân tay của máy chủ từ xa với dấu vân tay của một máy chủ khác?

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