How to append authorized_keys on the remote server with id_rsa.pub key

Question

How to append authorized_keys on the remote server with id_rsa.pub key from the local machine with a single command?

score 113 · Answer 1 · answered Jul 09 '15 at 22:27

113

ssh-copy-id user@remote_server

answered Jul 09 '15 at 22:27

Doug

4

This should be he approved answer; the others may be useful if needing to troubleshoot but they are hack-y alternatives to the official recommended method. – olisteadman Jan 29 '19 at 10:32
1

This of course only works if one is authorized to login to host with user/pass alone. Otherwise one will need to find a way to append to authorized_keys manually from within a shell on host system. How one chooses to do this is an exercise for the reader. – drkstr101 Oct 17 '20 at 23:28
1

None of these answers work if you do not have access to log into the remote server. – Doug Oct 18 '20 at 17:27

score 62 · Accepted Answer · edited Jul 20 '17 at 16:06

62

Adding an authorized key could be one-lined this way (use double-quotes so it's interpreted before sent):

ssh user@server "echo \"`cat ~/.ssh/id_rsa.pub`\" >> .ssh/authorized_keys"

edited Jul 20 '17 at 16:06

boatcoder

answered May 12 '14 at 00:20

Mose

Been using `ssh-copy-id` before but this command is great if you have a new public key (eg a new laptop) you want to add to one or a few servers that you already have access to. This allows you to authenticate using keys/settings from `~/.ssh/` but copy a different key. Bravo! – berezovskyi Feb 28 '21 at 20:47

score 32 · Answer 3 · answered Feb 25 '15 at 17:29

32

This does the trick:

cat ~/.ssh/id_rsa.pub | (ssh user@host "cat >> ~/.ssh/authorized_keys")

Appends the local public key the remote authorized_keys file.

answered Feb 25 '15 at 17:29

wcochran

@user3132194 parentheses are used for grouping here ... making sure the >> is on the remote shell – wcochran Apr 14 '17 at 13:40
1

`ssh user@host "cat >> ~/.ssh/authorized_keys" < ~/.ssh/id_rsa.pub` is a bit shorter and no subshell needed. – Sameer Jul 05 '17 at 17:19
1

I was trying to add Windows 10 built in openssh keys to my linux host, and this worked `type %userprofile%\.ssh\id_rsa.pub | ssh user@linux.local "cat >> .ssh/authorized_keys"` – Adarsha Feb 27 '21 at 04:51

score 14 · Answer 4 · edited Jan 09 '17 at 22:04

14

The ssh-copy-id program is the standard way but the key can be appended manually to the ~/.ssh/authorized_keys file:

cat ~/.ssh/id_rsa.pub | ssh username@host "mkdir ~/.ssh; cat >> ~/.ssh/authorized_keys"

This does not check if the key already exists and can lead to duplicates.

edited Jan 09 '17 at 22:04

Kevin

answered Apr 18 '15 at 13:43

score 12 · Answer 5 · edited Aug 01 '18 at 12:21

12

The most convenient option is the ssh-copy-id command. It can append the public key to ~/.ssh/authorized_keys. For example:

ssh-copy-id -f -i id_rsa.pub username@host

Where:

-f: force mode -- copy keys without trying to check if they are already installed
-i: [identity_file]

edited Aug 01 '18 at 12:21

anothernode

answered Aug 01 '18 at 12:01

Miroslaw

score 5 · Answer 6 · answered Dec 25 '18 at 08:52

5

You can avoid some of the quoting with:

ssh user@host tee -a .ssh/authorized_keys < ~/.ssh/id_rsa.pub

answered Dec 25 '18 at 08:52

user260532

6 Answers6