Unable to login to ec2 instance after running “sudo chmod 2770 /”












1















I am new to linux and AWS.



I ran sudo chmod 2770 / command on my ec2 instance and after that




I was getting Permission denied on everything I was doing(even using
ls or cd)




So I exited my connection(using cygwin) and tried to re-connect but now I get




Permission denied (publickey,gssapi-keyex,gssapi-with-mic)




I tried setting chmod 400 my.pem , chmod 600 my.pem, chmod 777 my.pem but nothing worked.

I am trying to connect using ssh -i my.pem ec2-user@xx.xx.xx.x which was working fine earlier.

What is the solution?










share|improve this question







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  • I have installed so many things on my instance. I don't want to loose it. Is there any way to get it back ?

    – iAmLearning
    49 mins ago






  • 1





    You should be using EBS snapshots to ensure you can recover your instance to a point in time that it's working. The advice from MLu below is what I'd have said too. Don't experiment on servers that have important data. I did something similar on my EC2 instance when I was learning, I had to restore to a snapshot because it was far too difficult to fix.

    – Tim
    16 mins ago
















1















I am new to linux and AWS.



I ran sudo chmod 2770 / command on my ec2 instance and after that




I was getting Permission denied on everything I was doing(even using
ls or cd)




So I exited my connection(using cygwin) and tried to re-connect but now I get




Permission denied (publickey,gssapi-keyex,gssapi-with-mic)




I tried setting chmod 400 my.pem , chmod 600 my.pem, chmod 777 my.pem but nothing worked.

I am trying to connect using ssh -i my.pem ec2-user@xx.xx.xx.x which was working fine earlier.

What is the solution?










share|improve this question







New contributor




iAmLearning is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.





















  • I have installed so many things on my instance. I don't want to loose it. Is there any way to get it back ?

    – iAmLearning
    49 mins ago






  • 1





    You should be using EBS snapshots to ensure you can recover your instance to a point in time that it's working. The advice from MLu below is what I'd have said too. Don't experiment on servers that have important data. I did something similar on my EC2 instance when I was learning, I had to restore to a snapshot because it was far too difficult to fix.

    – Tim
    16 mins ago














1












1








1








I am new to linux and AWS.



I ran sudo chmod 2770 / command on my ec2 instance and after that




I was getting Permission denied on everything I was doing(even using
ls or cd)




So I exited my connection(using cygwin) and tried to re-connect but now I get




Permission denied (publickey,gssapi-keyex,gssapi-with-mic)




I tried setting chmod 400 my.pem , chmod 600 my.pem, chmod 777 my.pem but nothing worked.

I am trying to connect using ssh -i my.pem ec2-user@xx.xx.xx.x which was working fine earlier.

What is the solution?










share|improve this question







New contributor




iAmLearning is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.












I am new to linux and AWS.



I ran sudo chmod 2770 / command on my ec2 instance and after that




I was getting Permission denied on everything I was doing(even using
ls or cd)




So I exited my connection(using cygwin) and tried to re-connect but now I get




Permission denied (publickey,gssapi-keyex,gssapi-with-mic)




I tried setting chmod 400 my.pem , chmod 600 my.pem, chmod 777 my.pem but nothing worked.

I am trying to connect using ssh -i my.pem ec2-user@xx.xx.xx.x which was working fine earlier.

What is the solution?







linux amazon-web-services amazon-ec2






share|improve this question







New contributor




iAmLearning is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.











share|improve this question







New contributor




iAmLearning is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.









share|improve this question




share|improve this question






New contributor




iAmLearning is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.









asked 59 mins ago









iAmLearningiAmLearning

1062




1062




New contributor




iAmLearning is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.





New contributor





iAmLearning is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.






iAmLearning is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.













  • I have installed so many things on my instance. I don't want to loose it. Is there any way to get it back ?

    – iAmLearning
    49 mins ago






  • 1





    You should be using EBS snapshots to ensure you can recover your instance to a point in time that it's working. The advice from MLu below is what I'd have said too. Don't experiment on servers that have important data. I did something similar on my EC2 instance when I was learning, I had to restore to a snapshot because it was far too difficult to fix.

    – Tim
    16 mins ago



















  • I have installed so many things on my instance. I don't want to loose it. Is there any way to get it back ?

    – iAmLearning
    49 mins ago






  • 1





    You should be using EBS snapshots to ensure you can recover your instance to a point in time that it's working. The advice from MLu below is what I'd have said too. Don't experiment on servers that have important data. I did something similar on my EC2 instance when I was learning, I had to restore to a snapshot because it was far too difficult to fix.

    – Tim
    16 mins ago

















I have installed so many things on my instance. I don't want to loose it. Is there any way to get it back ?

– iAmLearning
49 mins ago





I have installed so many things on my instance. I don't want to loose it. Is there any way to get it back ?

– iAmLearning
49 mins ago




1




1





You should be using EBS snapshots to ensure you can recover your instance to a point in time that it's working. The advice from MLu below is what I'd have said too. Don't experiment on servers that have important data. I did something similar on my EC2 instance when I was learning, I had to restore to a snapshot because it was far too difficult to fix.

– Tim
16 mins ago





You should be using EBS snapshots to ensure you can recover your instance to a point in time that it's working. The advice from MLu below is what I'd have said too. Don't experiment on servers that have important data. I did something similar on my EC2 instance when I was learning, I had to restore to a snapshot because it was far too difficult to fix.

– Tim
16 mins ago










1 Answer
1






active

oldest

votes


















2














Solution is to start a new instance and never do what you did again. It would be too complicated to try to properly recover all the permissions that you reset to 2770.



If you have any valuable files on the broken instance you can stop it, mount its root volume to the new instance and copy the files from there.





Update: as @GeraldSchneider points out you may be lucky if you didn't recursively change all the permissions everywhere. You'll have to start a new instance and use it to fix the root permissions back to 0755. Follow for example the instructions here: Changed AWS EC2 firewall rule and locked out of ssh (instead of Fix the firewall do sudo chmod 755 /mnt or wherever you mount the other disk).



Hope that helps :)






share|improve this answer


























  • My first thought was to rebuild the instance as well, but then I realized that the OP only changed the permission on / itself, not the directories and files below. It should be pretty easy to fix this, but I'm not familiar with EC2 and don't know how to mount the volume on a different instance.

    – Gerald Schneider
    37 mins ago











  • Is rebuilding possible ? I am just learning ec2 so I don't care about permissions/security. I just need it working again if possible.

    – iAmLearning
    19 mins ago











  • @GeraldSchneider good point, updated the answer.

    – MLu
    18 mins ago











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1 Answer
1






active

oldest

votes








1 Answer
1






active

oldest

votes









active

oldest

votes






active

oldest

votes









2














Solution is to start a new instance and never do what you did again. It would be too complicated to try to properly recover all the permissions that you reset to 2770.



If you have any valuable files on the broken instance you can stop it, mount its root volume to the new instance and copy the files from there.





Update: as @GeraldSchneider points out you may be lucky if you didn't recursively change all the permissions everywhere. You'll have to start a new instance and use it to fix the root permissions back to 0755. Follow for example the instructions here: Changed AWS EC2 firewall rule and locked out of ssh (instead of Fix the firewall do sudo chmod 755 /mnt or wherever you mount the other disk).



Hope that helps :)






share|improve this answer


























  • My first thought was to rebuild the instance as well, but then I realized that the OP only changed the permission on / itself, not the directories and files below. It should be pretty easy to fix this, but I'm not familiar with EC2 and don't know how to mount the volume on a different instance.

    – Gerald Schneider
    37 mins ago











  • Is rebuilding possible ? I am just learning ec2 so I don't care about permissions/security. I just need it working again if possible.

    – iAmLearning
    19 mins ago











  • @GeraldSchneider good point, updated the answer.

    – MLu
    18 mins ago
















2














Solution is to start a new instance and never do what you did again. It would be too complicated to try to properly recover all the permissions that you reset to 2770.



If you have any valuable files on the broken instance you can stop it, mount its root volume to the new instance and copy the files from there.





Update: as @GeraldSchneider points out you may be lucky if you didn't recursively change all the permissions everywhere. You'll have to start a new instance and use it to fix the root permissions back to 0755. Follow for example the instructions here: Changed AWS EC2 firewall rule and locked out of ssh (instead of Fix the firewall do sudo chmod 755 /mnt or wherever you mount the other disk).



Hope that helps :)






share|improve this answer


























  • My first thought was to rebuild the instance as well, but then I realized that the OP only changed the permission on / itself, not the directories and files below. It should be pretty easy to fix this, but I'm not familiar with EC2 and don't know how to mount the volume on a different instance.

    – Gerald Schneider
    37 mins ago











  • Is rebuilding possible ? I am just learning ec2 so I don't care about permissions/security. I just need it working again if possible.

    – iAmLearning
    19 mins ago











  • @GeraldSchneider good point, updated the answer.

    – MLu
    18 mins ago














2












2








2







Solution is to start a new instance and never do what you did again. It would be too complicated to try to properly recover all the permissions that you reset to 2770.



If you have any valuable files on the broken instance you can stop it, mount its root volume to the new instance and copy the files from there.





Update: as @GeraldSchneider points out you may be lucky if you didn't recursively change all the permissions everywhere. You'll have to start a new instance and use it to fix the root permissions back to 0755. Follow for example the instructions here: Changed AWS EC2 firewall rule and locked out of ssh (instead of Fix the firewall do sudo chmod 755 /mnt or wherever you mount the other disk).



Hope that helps :)






share|improve this answer















Solution is to start a new instance and never do what you did again. It would be too complicated to try to properly recover all the permissions that you reset to 2770.



If you have any valuable files on the broken instance you can stop it, mount its root volume to the new instance and copy the files from there.





Update: as @GeraldSchneider points out you may be lucky if you didn't recursively change all the permissions everywhere. You'll have to start a new instance and use it to fix the root permissions back to 0755. Follow for example the instructions here: Changed AWS EC2 firewall rule and locked out of ssh (instead of Fix the firewall do sudo chmod 755 /mnt or wherever you mount the other disk).



Hope that helps :)







share|improve this answer














share|improve this answer



share|improve this answer








edited 19 mins ago

























answered 42 mins ago









MLuMLu

8,21712141




8,21712141













  • My first thought was to rebuild the instance as well, but then I realized that the OP only changed the permission on / itself, not the directories and files below. It should be pretty easy to fix this, but I'm not familiar with EC2 and don't know how to mount the volume on a different instance.

    – Gerald Schneider
    37 mins ago











  • Is rebuilding possible ? I am just learning ec2 so I don't care about permissions/security. I just need it working again if possible.

    – iAmLearning
    19 mins ago











  • @GeraldSchneider good point, updated the answer.

    – MLu
    18 mins ago



















  • My first thought was to rebuild the instance as well, but then I realized that the OP only changed the permission on / itself, not the directories and files below. It should be pretty easy to fix this, but I'm not familiar with EC2 and don't know how to mount the volume on a different instance.

    – Gerald Schneider
    37 mins ago











  • Is rebuilding possible ? I am just learning ec2 so I don't care about permissions/security. I just need it working again if possible.

    – iAmLearning
    19 mins ago











  • @GeraldSchneider good point, updated the answer.

    – MLu
    18 mins ago

















My first thought was to rebuild the instance as well, but then I realized that the OP only changed the permission on / itself, not the directories and files below. It should be pretty easy to fix this, but I'm not familiar with EC2 and don't know how to mount the volume on a different instance.

– Gerald Schneider
37 mins ago





My first thought was to rebuild the instance as well, but then I realized that the OP only changed the permission on / itself, not the directories and files below. It should be pretty easy to fix this, but I'm not familiar with EC2 and don't know how to mount the volume on a different instance.

– Gerald Schneider
37 mins ago













Is rebuilding possible ? I am just learning ec2 so I don't care about permissions/security. I just need it working again if possible.

– iAmLearning
19 mins ago





Is rebuilding possible ? I am just learning ec2 so I don't care about permissions/security. I just need it working again if possible.

– iAmLearning
19 mins ago













@GeraldSchneider good point, updated the answer.

– MLu
18 mins ago





@GeraldSchneider good point, updated the answer.

– MLu
18 mins ago










iAmLearning is a new contributor. Be nice, and check out our Code of Conduct.










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iAmLearning is a new contributor. Be nice, and check out our Code of Conduct.












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