sshgitlab-cipipelinescpsshd

How can I fix "kex_exchange_identification: read: Connection reset by peer"?

I want to copy data with scp in a GitLab pipeline using PRIVATE_KEY.

The error is:

kex_exchange_identification: read: Connection reset by peer
Connection reset by x.x.x.x port 22
lost connection

Pipeline log:

$ mkdir -p ~/.ssh

$ echo "$SSH_PRIVATE_KEY" | tr -d '\r' > ~/.ssh/id_rsa

$ chmod 600 ~/.ssh/id_rsa

$ eval "$(ssh-agent -s)"
Agent pid 22

$ ssh-add ~/.ssh/id_rsa
Identity added: /root/.ssh/id_rsa (/root/.ssh/id_rsa)

$ ssh-keyscan -H $IP >> ~/.ssh/known_hosts
# x.x.x.x:22 SSH-2.0-OpenSSH_7.2p2 Ubuntu-4ubuntu2.10
# x.x.x.x:22 SSH-2.0-OpenSSH_7.2p2 Ubuntu-4ubuntu2.10

$ scp -rv api.yml root@$IP:/home/services/test/

Executing: program /usr/bin/ssh host x.x.x.x, user root, command scp -v -r -t /home/services/test/

OpenSSH_8.6p1, OpenSSL 1.1.1l  24 Aug 2021
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: Authenticator provider $SSH_SK_PROVIDER did not resolve; disabling
debug1: Connecting to x.x.x.x [x.x.x.x] port 22.
debug1: Connection established.
debug1: identity file /root/.ssh/id_rsa type -1
debug1: identity file /root/.ssh/id_rsa-cert type -1
debug1: identity file /root/.ssh/id_dsa type -1
debug1: identity file /root/.ssh/id_dsa-cert type -1
debug1: identity file /root/.ssh/id_ecdsa type -1
debug1: identity file /root/.ssh/id_ecdsa-cert type -1
debug1: identity file /root/.ssh/id_ecdsa_sk type -1
debug1: identity file /root/.ssh/id_ecdsa_sk-cert type -1
debug1: identity file /root/.ssh/id_ed25519 type -1
debug1: identity file /root/.ssh/id_ed25519-cert type -1
debug1: identity file /root/.ssh/id_ed25519_sk type -1
debug1: identity file /root/.ssh/id_ed25519_sk-cert type -1
debug1: identity file /root/.ssh/id_xmss type -1
debug1: identity file /root/.ssh/id_xmss-cert type -1
debug1: Local version string SSH-2.0-OpenSSH_8.6
kex_exchange_identification: read: Connection reset by peer
Connection reset by x.x.x.x port 22
lost connection
Solution 
  • kex_exchange_identification: read: Connection reset by peer

    When an SSH client connects to an SSH server, the server starts by sending a version string to the client. The error that you're getting means that the TCP connection from the client to the server was "abnormally closed" while the client was waiting for this data from the server, in other words immediately after the TCP connection was opened.

    As a practical matter, it's likely to mean one of two things:

    1. The SSH server process malfunctioned (crashed), or perhaps it detected some serious issue causing it to exit immediately.
    2. Some firewall is interfering with connections to the ssh server.

    It looks like the ssh-keyscan program was able to connect to the server and get a version string without an error. So the SSH server process is apparently able to talk to a client without crashing.

    You should talk the administrators of this x.x.x.x host and the network that it's attached to, to see if they can identify the problem from their end. It's possible that something—a firewall, or the ssh server process itself—is seeing the multiple connections, first from the ssh-keyscan process, then by the scp program, as an intrusion attempt. And it's blocking the second connection attempt.