What can I do if someone tampers with my SSH public key?Why is a remote server asking me to generate...
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What can I do if someone tampers with my SSH public key?
Why is a remote server asking me to generate public/private SSH keys?How does SSH encryption work?Install public key via ssh-copy-id for other usersLogin with SSH public key doesn't workCan't ssh in with public keyWhat exactly happens when you use SSH without generating a key pair?What stops anybody from copying their ssh public key onto my server?Missing begin marker error with public key ssh loginpscp between local (Windows) and remote (Linux) with private keySSH “refused key” only with public IP, works locally
I understand private keys being compromised is a huge risk; however, what about public keys. What if they are tampered with?
If someone were to access my public key associated with the private key I use to SSH in the Linux server, and modify it, wouldn’t that prevent me access to the server; therefore, affecting availability on my end?
linux encryption
edited 58 mins ago
JakeGould
31.7k1097140
asked 16 hours ago
KevKev
363
add a comment |
I understand private keys being compromised is a huge risk; however, what about public keys. What if they are tampered with?
If someone were to access my public key associated with the private key I use to SSH in the Linux server, and modify it, wouldn’t that prevent me access to the server; therefore, affecting availability on my end?
linux encryption
edited 58 mins ago
JakeGould
31.7k1097140
asked 16 hours ago
KevKev
363
5
Your public key is supposed to be shared. It is the key that encrypts the data, your private key, decrypts the data.
– Ramhound
15 hours ago
add a comment |
I understand private keys being compromised is a huge risk; however, what about public keys. What if they are tampered with?
If someone were to access my public key associated with the private key I use to SSH in the Linux server, and modify it, wouldn’t that prevent me access to the server; therefore, affecting availability on my end?
linux encryption
edited 58 mins ago
JakeGould
31.7k1097140
asked 16 hours ago
KevKev
363
I understand private keys being compromised is a huge risk; however, what about public keys. What if they are tampered with?
If someone were to access my public key associated with the private key I use to SSH in the Linux server, and modify it, wouldn’t that prevent me access to the server; therefore, affecting availability on my end?
linux encryption
linux encryption
edited 58 mins ago
JakeGould
31.7k1097140
asked 16 hours ago
KevKev
363
edited 58 mins ago
JakeGould
31.7k1097140
asked 16 hours ago
KevKev
363
edited 58 mins ago
JakeGould
31.7k1097140
edited 58 mins ago
JakeGould
31.7k1097140
edited 58 mins ago
JakeGould
31.7k1097140
31.7k1097140
asked 16 hours ago
KevKev
363
asked 16 hours ago
KevKev
363
asked 16 hours ago
KevKev
363
363
5
Your public key is supposed to be shared. It is the key that encrypts the data, your private key, decrypts the data.
– Ramhound
15 hours ago
add a comment |
5
Your public key is supposed to be shared. It is the key that encrypts the data, your private key, decrypts the data.
– Ramhound
15 hours ago
5
5
Your public key is supposed to be shared. It is the key that encrypts the data, your private key, decrypts the data.
– Ramhound
15 hours ago
Your public key is supposed to be shared. It is the key that encrypts the data, your private key, decrypts the data.
– Ramhound
15 hours ago
add a comment |
3 Answers
3
active
oldest
votes
You can always regenerate a public key as long as you have the private key.
You ask:
If someone were to access my public key associated with the private key I use to SSH in the Linux server, and modify it, wouldn’t that prevent me access to the server; therefor, affecting availability on my end?
So is the situation you are concerned about something like you leave your computer on, don’t put it to sleep, run away to do something, then someone goes to your computer and just adds a few characters to your public key so it is effectively damaged? Or even deletes it?
No worries as long as you have your private key. Just run this command:
ssh-keygen -y -f ~/.ssh/id_rsa > ~/.ssh/id_rsa.pub
And your public key will be regenerated. Just note that the comment at the end of the public key line that allows you to more easily identify which key is what—via what is typically an email address—won’t be added to this id_rsa.pub via this method. So you might want to open it up in a text editor and manually add that.
About your other concerns.
Now if you are concerned about someone hacking the public key on a remote machine in a way that denies you access? Honestly, you would have a fairly larger issue to deal with in a case like that.
Typically, someone would need to be able to gain root access on a machine to do that. And that is not unheard of but a rare occurrence at best.
answered 16 hours ago
JakeGouldJakeGould
31.7k1097140
add a comment |
The whole point of a public key is to be widely known. It can be vetted by the PKI (public key infrastructure). You can sign messages (and other things) with your private key locally on your PC, and others can confirm that the message came from you.
Similarly, the public key can be put into the SSH config files on remote servers. When you SSH into those servers, they present a challenge that can only be correctly answered by someone with the proper private key.
Your original question asked:
"If someone were to access my public key associated with the private key I use to SSH in the Linux server, and modify it"...
then it would no longer be the same public key. You can regenerate the public key immediately for another admin to set the proper public key.
You have secondary worries: Who else can get access to my machine, what can they do, and how do I recover? hose answers are complicated and situational.
There are many good resources on SSH and PKI on the web... here's a good start: SSH Essentials: Working with SSH Servers, Clients, and Keys
edited 16 hours ago
JakeGould
31.7k1097140
answered 16 hours ago
Christopher HostageChristopher Hostage
3,6001028
add a comment |
It sounds like you are asking if someone got into "my" Linux box, modified the .ssh/authorized_keys, which contains the public keys which allow access to the Linux box, and "modify it, wouldn’t that prevent me access to the server; therefor(e), affecting availability on my end?"
Yes if the public key is changed in the authorized_keys file it won't match your private key, but this is like saying, someone got inside your house, changed your door lock, and now your house key doesn't work anymore.
How did they get in the first place to make the change?
Only root and login owner can change their own authorized_keys file, so those would be your suspects.
answered 9 hours ago
MarkTMarkT
511
New contributor
MarkT is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
Good answer. I think the questioner may be confused what it means for a key to be "public". Just because anybody can see your public key doesn't mean anybody can change it.
– hackerb9
4 mins ago
add a comment |
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3 Answers
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3 Answers
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You can always regenerate a public key as long as you have the private key.
You ask:
If someone were to access my public key associated with the private key I use to SSH in the Linux server, and modify it, wouldn’t that prevent me access to the server; therefor, affecting availability on my end?
So is the situation you are concerned about something like you leave your computer on, don’t put it to sleep, run away to do something, then someone goes to your computer and just adds a few characters to your public key so it is effectively damaged? Or even deletes it?
No worries as long as you have your private key. Just run this command:
ssh-keygen -y -f ~/.ssh/id_rsa > ~/.ssh/id_rsa.pub
And your public key will be regenerated. Just note that the comment at the end of the public key line that allows you to more easily identify which key is what—via what is typically an email address—won’t be added to this id_rsa.pub via this method. So you might want to open it up in a text editor and manually add that.
About your other concerns.
Now if you are concerned about someone hacking the public key on a remote machine in a way that denies you access? Honestly, you would have a fairly larger issue to deal with in a case like that.
Typically, someone would need to be able to gain root access on a machine to do that. And that is not unheard of but a rare occurrence at best.
answered 16 hours ago
JakeGouldJakeGould
31.7k1097140
add a comment |
You can always regenerate a public key as long as you have the private key.
You ask:
If someone were to access my public key associated with the private key I use to SSH in the Linux server, and modify it, wouldn’t that prevent me access to the server; therefor, affecting availability on my end?
So is the situation you are concerned about something like you leave your computer on, don’t put it to sleep, run away to do something, then someone goes to your computer and just adds a few characters to your public key so it is effectively damaged? Or even deletes it?
No worries as long as you have your private key. Just run this command:
ssh-keygen -y -f ~/.ssh/id_rsa > ~/.ssh/id_rsa.pub
And your public key will be regenerated. Just note that the comment at the end of the public key line that allows you to more easily identify which key is what—via what is typically an email address—won’t be added to this id_rsa.pub via this method. So you might want to open it up in a text editor and manually add that.
About your other concerns.
Now if you are concerned about someone hacking the public key on a remote machine in a way that denies you access? Honestly, you would have a fairly larger issue to deal with in a case like that.
Typically, someone would need to be able to gain root access on a machine to do that. And that is not unheard of but a rare occurrence at best.
answered 16 hours ago
JakeGouldJakeGould
31.7k1097140
add a comment |
You can always regenerate a public key as long as you have the private key.
You ask:
If someone were to access my public key associated with the private key I use to SSH in the Linux server, and modify it, wouldn’t that prevent me access to the server; therefor, affecting availability on my end?
So is the situation you are concerned about something like you leave your computer on, don’t put it to sleep, run away to do something, then someone goes to your computer and just adds a few characters to your public key so it is effectively damaged? Or even deletes it?
No worries as long as you have your private key. Just run this command:
ssh-keygen -y -f ~/.ssh/id_rsa > ~/.ssh/id_rsa.pub
And your public key will be regenerated. Just note that the comment at the end of the public key line that allows you to more easily identify which key is what—via what is typically an email address—won’t be added to this id_rsa.pub via this method. So you might want to open it up in a text editor and manually add that.
About your other concerns.
Now if you are concerned about someone hacking the public key on a remote machine in a way that denies you access? Honestly, you would have a fairly larger issue to deal with in a case like that.
Typically, someone would need to be able to gain root access on a machine to do that. And that is not unheard of but a rare occurrence at best.
answered 16 hours ago
JakeGouldJakeGould
31.7k1097140
You can always regenerate a public key as long as you have the private key.
You ask:
If someone were to access my public key associated with the private key I use to SSH in the Linux server, and modify it, wouldn’t that prevent me access to the server; therefor, affecting availability on my end?
So is the situation you are concerned about something like you leave your computer on, don’t put it to sleep, run away to do something, then someone goes to your computer and just adds a few characters to your public key so it is effectively damaged? Or even deletes it?
No worries as long as you have your private key. Just run this command:
ssh-keygen -y -f ~/.ssh/id_rsa > ~/.ssh/id_rsa.pub
And your public key will be regenerated. Just note that the comment at the end of the public key line that allows you to more easily identify which key is what—via what is typically an email address—won’t be added to this id_rsa.pub via this method. So you might want to open it up in a text editor and manually add that.
About your other concerns.
Now if you are concerned about someone hacking the public key on a remote machine in a way that denies you access? Honestly, you would have a fairly larger issue to deal with in a case like that.
Typically, someone would need to be able to gain root access on a machine to do that. And that is not unheard of but a rare occurrence at best.
answered 16 hours ago
JakeGouldJakeGould
31.7k1097140
edited 15 hours ago
answered 16 hours ago
JakeGouldJakeGould
31.7k1097140
answered 16 hours ago
JakeGouldJakeGould
31.7k1097140
answered 16 hours ago
JakeGouldJakeGould
31.7k1097140
31.7k1097140
add a comment |
add a comment |
The whole point of a public key is to be widely known. It can be vetted by the PKI (public key infrastructure). You can sign messages (and other things) with your private key locally on your PC, and others can confirm that the message came from you.
Similarly, the public key can be put into the SSH config files on remote servers. When you SSH into those servers, they present a challenge that can only be correctly answered by someone with the proper private key.
Your original question asked:
"If someone were to access my public key associated with the private key I use to SSH in the Linux server, and modify it"...
then it would no longer be the same public key. You can regenerate the public key immediately for another admin to set the proper public key.
You have secondary worries: Who else can get access to my machine, what can they do, and how do I recover? hose answers are complicated and situational.
There are many good resources on SSH and PKI on the web... here's a good start: SSH Essentials: Working with SSH Servers, Clients, and Keys
edited 16 hours ago
JakeGould
31.7k1097140
answered 16 hours ago
Christopher HostageChristopher Hostage
3,6001028
add a comment |
The whole point of a public key is to be widely known. It can be vetted by the PKI (public key infrastructure). You can sign messages (and other things) with your private key locally on your PC, and others can confirm that the message came from you.
Similarly, the public key can be put into the SSH config files on remote servers. When you SSH into those servers, they present a challenge that can only be correctly answered by someone with the proper private key.
Your original question asked:
"If someone were to access my public key associated with the private key I use to SSH in the Linux server, and modify it"...
then it would no longer be the same public key. You can regenerate the public key immediately for another admin to set the proper public key.
You have secondary worries: Who else can get access to my machine, what can they do, and how do I recover? hose answers are complicated and situational.
There are many good resources on SSH and PKI on the web... here's a good start: SSH Essentials: Working with SSH Servers, Clients, and Keys
edited 16 hours ago
JakeGould
31.7k1097140
answered 16 hours ago
Christopher HostageChristopher Hostage
3,6001028
add a comment |
The whole point of a public key is to be widely known. It can be vetted by the PKI (public key infrastructure). You can sign messages (and other things) with your private key locally on your PC, and others can confirm that the message came from you.
Similarly, the public key can be put into the SSH config files on remote servers. When you SSH into those servers, they present a challenge that can only be correctly answered by someone with the proper private key.
Your original question asked:
"If someone were to access my public key associated with the private key I use to SSH in the Linux server, and modify it"...
then it would no longer be the same public key. You can regenerate the public key immediately for another admin to set the proper public key.
You have secondary worries: Who else can get access to my machine, what can they do, and how do I recover? hose answers are complicated and situational.
There are many good resources on SSH and PKI on the web... here's a good start: SSH Essentials: Working with SSH Servers, Clients, and Keys
edited 16 hours ago
JakeGould
31.7k1097140
answered 16 hours ago
Christopher HostageChristopher Hostage
3,6001028
The whole point of a public key is to be widely known. It can be vetted by the PKI (public key infrastructure). You can sign messages (and other things) with your private key locally on your PC, and others can confirm that the message came from you.
Similarly, the public key can be put into the SSH config files on remote servers. When you SSH into those servers, they present a challenge that can only be correctly answered by someone with the proper private key.
Your original question asked:
"If someone were to access my public key associated with the private key I use to SSH in the Linux server, and modify it"...
then it would no longer be the same public key. You can regenerate the public key immediately for another admin to set the proper public key.
You have secondary worries: Who else can get access to my machine, what can they do, and how do I recover? hose answers are complicated and situational.
There are many good resources on SSH and PKI on the web... here's a good start: SSH Essentials: Working with SSH Servers, Clients, and Keys
edited 16 hours ago
JakeGould
31.7k1097140
answered 16 hours ago
Christopher HostageChristopher Hostage
3,6001028
edited 16 hours ago
JakeGould
31.7k1097140
edited 16 hours ago
JakeGould
31.7k1097140
edited 16 hours ago
JakeGould
31.7k1097140
31.7k1097140
answered 16 hours ago
Christopher HostageChristopher Hostage
3,6001028
answered 16 hours ago
Christopher HostageChristopher Hostage
3,6001028
answered 16 hours ago
Christopher HostageChristopher Hostage
3,6001028
3,6001028
add a comment |
add a comment |
It sounds like you are asking if someone got into "my" Linux box, modified the .ssh/authorized_keys, which contains the public keys which allow access to the Linux box, and "modify it, wouldn’t that prevent me access to the server; therefor(e), affecting availability on my end?"
Yes if the public key is changed in the authorized_keys file it won't match your private key, but this is like saying, someone got inside your house, changed your door lock, and now your house key doesn't work anymore.
How did they get in the first place to make the change?
Only root and login owner can change their own authorized_keys file, so those would be your suspects.
answered 9 hours ago
MarkTMarkT
511
New contributor
MarkT is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
Good answer. I think the questioner may be confused what it means for a key to be "public". Just because anybody can see your public key doesn't mean anybody can change it.
– hackerb9
4 mins ago
add a comment |
It sounds like you are asking if someone got into "my" Linux box, modified the .ssh/authorized_keys, which contains the public keys which allow access to the Linux box, and "modify it, wouldn’t that prevent me access to the server; therefor(e), affecting availability on my end?"
Yes if the public key is changed in the authorized_keys file it won't match your private key, but this is like saying, someone got inside your house, changed your door lock, and now your house key doesn't work anymore.
How did they get in the first place to make the change?
Only root and login owner can change their own authorized_keys file, so those would be your suspects.
answered 9 hours ago
MarkTMarkT
511
New contributor
MarkT is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
Good answer. I think the questioner may be confused what it means for a key to be "public". Just because anybody can see your public key doesn't mean anybody can change it.
– hackerb9
4 mins ago
add a comment |
It sounds like you are asking if someone got into "my" Linux box, modified the .ssh/authorized_keys, which contains the public keys which allow access to the Linux box, and "modify it, wouldn’t that prevent me access to the server; therefor(e), affecting availability on my end?"
Yes if the public key is changed in the authorized_keys file it won't match your private key, but this is like saying, someone got inside your house, changed your door lock, and now your house key doesn't work anymore.
How did they get in the first place to make the change?
Only root and login owner can change their own authorized_keys file, so those would be your suspects.
answered 9 hours ago
MarkTMarkT
511
New contributor
MarkT is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
It sounds like you are asking if someone got into "my" Linux box, modified the .ssh/authorized_keys, which contains the public keys which allow access to the Linux box, and "modify it, wouldn’t that prevent me access to the server; therefor(e), affecting availability on my end?"
Yes if the public key is changed in the authorized_keys file it won't match your private key, but this is like saying, someone got inside your house, changed your door lock, and now your house key doesn't work anymore.
How did they get in the first place to make the change?
Only root and login owner can change their own authorized_keys file, so those would be your suspects.
answered 9 hours ago
MarkTMarkT
511
New contributor
MarkT is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
answered 9 hours ago
MarkTMarkT
511
New contributor
MarkT is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
answered 9 hours ago
MarkTMarkT
511
answered 9 hours ago
MarkTMarkT
511
511
New contributor
MarkT is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
New contributor
MarkT is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
MarkT is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
Good answer. I think the questioner may be confused what it means for a key to be "public". Just because anybody can see your public key doesn't mean anybody can change it.
– hackerb9
4 mins ago
add a comment |
Good answer. I think the questioner may be confused what it means for a key to be "public". Just because anybody can see your public key doesn't mean anybody can change it.
– hackerb9
4 mins ago
Good answer. I think the questioner may be confused what it means for a key to be "public". Just because anybody can see your public key doesn't mean anybody can change it.
– hackerb9
4 mins ago
Good answer. I think the questioner may be confused what it means for a key to be "public". Just because anybody can see your public key doesn't mean anybody can change it.
– hackerb9
4 mins ago
add a comment |
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5
Your public key is supposed to be shared. It is the key that encrypts the data, your private key, decrypts the data.
– Ramhound
15 hours ago