使用与 Windows 主机共享的存储库在“git fetch”上的 Ubuntu VM 上突然出现“权限被拒绝（公钥）”

Question

I have a Windows 10 laptop. I have an Ubuntu 18.04 VM running on that laptop. I have a few dozen git repositories on the laptop with the remote being our intranet BitBucket instance. I reference the exact same repositories on the Linux VM by using shared folders. This setup has worked fine for quite a while. I can do all the same git operations on either the Windows host or the Linux VM, and they all work fine, and any changes from those operations are reflected on the other OS.

All of these repositories are cloned using ssh, with a keypair registered in the BitBucket server. Again, this has worked fine for a long time.

Just today, I tried to do some operations on the Linux VM, like "git fetch", and it's failing like this:

git@.....com: Permission denied (publickey).
fatal: Could not read from remote repository.

Please make sure you have the correct access rights
and the repository exists.

I tested this from the shell, and also from Eclipse EGit, with the same result.

I then went back to the Windows host, to the same repository (remember I use shared folders on the VM to point to the same repositories), and did the same thing, and it works perfectly fine.

Our firewall team has made some changes to our firewall in recent months, and they don't tend to announce changes, so that's an unknown.

I'm not sure what information I can get to diagnose this.

Update :

Setting GIT_SSH_COMMAND="ssh -vvv" is very informative. This tells me:

debug1: Offering public key: RSA SHA256:...
debug3: send_pubkey_test
debug3: send packet: type 50
debug2: we sent a publickey packet, wait for reply
debug3: receive packet: type 51
debug1: Authentications that can continue: publickey
debug1: Trying private key: <myhome>/.ssh/id_dsa
debug3: no such identity: <myhome>/.ssh/id_dsa: No such file or directory
debug1: Trying private key: <myhome>/.ssh/id_ecdsa
debug3: no such identity: <myhome>/.ssh/id_ecdsa: No such file or directory
debug1: Trying private key: <myhome>/.ssh/id_ed25519
debug3: no such identity: <myhome>/.ssh/id_ed25519: No such file or directory
debug2: we did not send a packet, disable method
debug1: No more authentication methods to try.

For the longest time, I've had my key pairs in ~/.ssh as "id_rsa" and "id_rsa.pub". This is looking for "dsa", not "rsa". I see some arguments on the net about which should be used, but I would think that rsa is still valid for this. It's not clear what should be done here.

Update :

When I added "IdentityFile", it still didn't work, but it clearly noticed the new setting and did something different. Now when I'm comparing the text output both with and without that setting, I see that even without the "IdentityFile" setting, it was still finding the "id_rsa" file, I just didn't notice it.

I guess the following elided output shows the difference in the verbose "git fetch" output both without and with the new setting:

*** withoutidentity.txt 2020-08-13 06:29:56.662638000 -0700
--- withidentity.txt    2020-08-13 06:30:10.786638000 -0700
***************
*** 10,27 ****
  debug1: identity file <myhome>/.ssh/id_rsa type 0
  debug1: key_load_public: No such file or directory
  debug1: identity file <myhome>/.ssh/id_rsa-cert type -1
- debug1: key_load_public: No such file or directory
- debug1: identity file <myhome>/.ssh/id_dsa type -1
- debug1: key_load_public: No such file or directory
- debug1: identity file <myhome>/.ssh/id_dsa-cert type -1
- debug1: key_load_public: No such file or directory
- debug1: identity file <myhome>/.ssh/id_ecdsa type -1
- debug1: key_load_public: No such file or directory
- debug1: identity file <myhome>/.ssh/id_ecdsa-cert type -1
- debug1: key_load_public: No such file or directory
- debug1: identity file <myhome>/.ssh/id_ed25519 type -1
- debug1: key_load_public: No such file or directory
- debug1: identity file <myhome>/.ssh/id_ed25519-cert type -1
  debug1: Local version string SSH-2.0-OpenSSH_7.6p1 Ubuntu-4ubuntu0.3
  debug1: Remote protocol version 2.0, remote software version APACHE-SSHD-2.3.0
  debug1: no match: APACHE-SSHD-2.3.0
--- 10,15 ----
***************
*** 90,100 ****
  debug1: SSH2_MSG_NEWKEYS received
  debug2: set_newkeys: mode 0
  debug1: rekey after 4294967296 blocks
! debug2: key: <myhome>/.ssh/id_rsa (0x55b82d8f2390), agent
! debug2: key: davmichaelkarr@gmail.com (0x55b82d8f7c50), agent
! debug2: key: <myhome>/.ssh/id_dsa ((nil))
! debug2: key: <myhome>/.ssh/id_ecdsa ((nil))
! debug2: key: <myhome>/.ssh/id_ed25519 ((nil))
  debug3: send packet: type 5
  debug3: receive packet: type 6
  debug2: service_accept: ssh-userauth
--- 78,85 ----
  debug1: SSH2_MSG_NEWKEYS received
  debug2: set_newkeys: mode 0
  debug1: rekey after 4294967296 blocks
! debug2: key: <myhome>/.ssh/id_rsa (0x562f96fec330), explicit, agent
! debug2: key: davmichaelkarr@gmail.com (0x562f96ff1b30), agent
  debug3: send packet: type 5
  debug3: receive packet: type 6
  debug2: service_accept: ssh-userauth
***************
*** 123,134 ****
  debug2: we sent a publickey packet, wait for reply
  debug3: receive packet: type 51
  debug1: Authentications that can continue: publickey
- debug1: Trying private key: <myhome>/.ssh/id_dsa
- debug3: no such identity: <myhome>/.ssh/id_dsa: No such file or directory
- debug1: Trying private key: <myhome>/.ssh/id_ecdsa
- debug3: no such identity: <myhome>/.ssh/id_ecdsa: No such file or directory
- debug1: Trying private key: <myhome>/.ssh/id_ed25519
- debug3: no such identity: <myhome>/.ssh/id_ed25519: No such file or directory
  debug2: we did not send a packet, disable method
  debug1: No more authentication methods to try.
  git@codecloud.web.att.com: Permission denied (publickey).
--- 108,113 ----

Answer 1

It feels like there is too much uncertainty to give a precise answer. Did you try to get extra debug information by running ssh with verbose output? It could hint what exactly is wrong:

Try this:

GIT_SSH_COMMAND="ssh -vvv" git clone or git fetch

Update:

Alright, so the ssh verbose output tells that it did try a couple of keys however none of them have been found and so it is unable to authenticate you.

Do you have anything in your.ssh/config? I usually put there which key shall be used with which repository. For example on my machine I have a such entry:

$ cat .ssh/config
Host gitlab.com
    Hostname gitlab.com
    User git
    IdentityFile ~/.ssh/id_rsa-gitlab

It tells ssh to use this exact key for authentication.