Question
I’m currently trying to open a reverse shell into a docker container on another computer in my network. Once this connection is established, I want to open a shell in the docker container, and from there, ssh into the computer that opened the reverse shell, using said reverse shell connection.
While I can establish the reverse shell connection, I fail to tunnel back from the host that received the reverse shell, because the establishing hosts seems to reset the connection.
Note that the scenario works when I eliminate Docker, meaning I reverse tunnel from the first computer to the computer that would normally run Docker and then connect back from this computer through the tunnel.
What am I doing wrong here?
Setup
I’ve setup a container based on debian with ssh installed.
The login in the Docker container is handled by the Google Authenticator (GA) PAM module, which implements time based one time password authentication according to RFC6238. I’m using this java implementation to generate the one time passwords, but since it’s an open standard, many other implementations exist.
The login on the host that initiates the reverse shell is a normal password based login.
The complete files for building and running the container can be downloaded –here–.
In short, this is my Dockerfile…
FROM debian
RUN apt-get update && apt-get install -y openssh-server expect libpam-google-authenticator
RUN echo "root:password" | chpasswd
USER root
# Setup SSH and PAM
COPY etc/pam.d/sshd /etc/pam.d/
COPY etc/ssh/sshd_config /etc/ssh/
RUN mkdir /run/sshd
RUN chmod 0755 /run/sshd
RUN google-authenticator --no-confirm --time-based --disallow-reuse --no-rate-limit --force --window-size=3
CMD ["/usr/sbin/sshd", "-D"]
…my compose.yml…
services:
revssh-server:
image: revssh
container_name: RevSSH-server
volumes:
- ./google_authenticator:/root/.google_authenticator
ports:
- 2222:22
…the file /etc/ssh/sshd_config…
# This is the sshd server system-wide configuration file. See
# sshd_config(5) for more information.
# This sshd was compiled with PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games
# The strategy used for options in the default sshd_config shipped with
# OpenSSH is to specify options with their default value where
# possible, but leave them commented. Uncommented options override the
# default value.
Include /etc/ssh/sshd_config.d/*.conf
#Port 22
#AddressFamily any
#ListenAddress 0.0.0.0
#ListenAddress ::
#HostKey /etc/ssh/ssh_host_rsa_key
#HostKey /etc/ssh/ssh_host_ecdsa_key
#HostKey /etc/ssh/ssh_host_ed25519_key
# Ciphers and keying
#RekeyLimit default none
# Logging
#SyslogFacility AUTH
#LogLevel INFO
# Authentication:
#LoginGraceTime 2m
PermitRootLogin yes
#StrictModes yes
#MaxAuthTries 6
#MaxSessions 10
#PubkeyAuthentication yes
# Expect .ssh/authorized_keys2 to be disregarded by default in future.
#AuthorizedKeysFile .ssh/authorized_keys .ssh/authorized_keys2
#AuthorizedPrincipalsFile none
#AuthorizedKeysCommand none
#AuthorizedKeysCommandUser nobody
# For this to work you will also need host keys in /etc/ssh/ssh_known_hosts
#HostbasedAuthentication no
# Change to yes if you don't trust ~/.ssh/known_hosts for
# HostbasedAuthentication
#IgnoreUserKnownHosts no
# Don't read the user's ~/.rhosts and ~/.shosts files
#IgnoreRhosts yes
# To disable tunneled clear text passwords, change to no here!
PasswordAuthentication no
#PermitEmptyPasswords no
# Change to yes to enable challenge-response passwords (beware issues with
# some PAM modules and threads)
#KbdInteractiveAuthentication no
ChallengeResponseAuthentication yes
# Kerberos options
#KerberosAuthentication no
#KerberosOrLocalPasswd yes
#KerberosTicketCleanup yes
#KerberosGetAFSToken no
# GSSAPI options
#GSSAPIAuthentication no
#GSSAPICleanupCredentials yes
#GSSAPIStrictAcceptorCheck yes
#GSSAPIKeyExchange no
# Set this to 'yes' to enable PAM authentication, account processing,
# and session processing. If this is enabled, PAM authentication will
# be allowed through the KbdInteractiveAuthentication and
# PasswordAuthentication. Depending on your PAM configuration,
# PAM authentication via KbdInteractiveAuthentication may bypass
# the setting of "PermitRootLogin prohibit-password".
# If you just want the PAM account and session checks to run without
# PAM authentication, then enable this but set PasswordAuthentication
# and KbdInteractiveAuthentication to 'no'.
UsePAM yes
#AllowAgentForwarding yes
#AllowTcpForwarding yes
#GatewayPorts no
X11Forwarding yes
#X11DisplayOffset 10
#X11UseLocalhost yes
#PermitTTY yes
PrintMotd no
#PrintLastLog yes
#TCPKeepAlive yes
#PermitUserEnvironment no
#Compression delayed
#ClientAliveInterval 0
#ClientAliveCountMax 3
#UseDNS no
#PidFile /run/sshd.pid
#MaxStartups 10:30:100
#PermitTunnel no
#ChrootDirectory none
#VersionAddendum none
# no default banner path
#Banner none
# Allow client to pass locale environment variables
AcceptEnv LANG LC_*
# override default of no subsystems
Subsystem sftp /usr/lib/openssh/sftp-server
# Example of overriding settings on a per-user basis
#Match User anoncvs
# X11Forwarding no
# AllowTcpForwarding no
# PermitTTY no
# ForceCommand cvs server
…and the file /etc/pam.d/sshd
# PAM configuration for the Secure Shell service
# Standard Un*x authentication.
#@include common-auth
# Disallow non-root logins when /etc/nologin exists.
account required pam_nologin.so
# Uncomment and edit /etc/security/access.conf if you need to set complex
# access limits that are hard to express in sshd_config.
# account required pam_access.so
# Standard Un*x authorization.
@include common-account
# SELinux needs to be the first session rule. This ensures that any
# lingering context has been cleared. Without this it is possible that a
# module could execute code in the wrong domain.
session [success=ok ignore=ignore module_unknown=ignore default=bad] pam_selinux.so close
# Set the loginuid process attribute.
session required pam_loginuid.so
# Create a new session keyring.
session optional pam_keyinit.so force revoke
# Standard Un*x session setup and teardown.
@include common-session
# Print the message of the day upon successful login.
# This includes a dynamically generated part from /run/motd.dynamic
# and a static (admin-editable) part from /etc/motd.
session optional pam_motd.so motd=/run/motd.dynamic
session optional pam_motd.so noupdate
# Print the status of the user's mailbox upon successful login.
session optional pam_mail.so standard noenv # [1]
# Set up user limits from /etc/security/limits.conf.
session required pam_limits.so
# Read environment variables from /etc/environment and
# /etc/security/pam_env.conf.
session required pam_env.so # [1]
# In Debian 4.0 (etch), locale-related environment variables were moved to
# /etc/default/locale, so read that as well.
session required pam_env.so user_readenv=1 envfile=/etc/default/locale
# SELinux needs to intervene at login time to ensure that the process starts
# in the proper default security context. Only sessions which are intended
# to run in the user's context should be run after this.
session [success=ok ignore=ignore module_unknown=ignore default=bad] pam_selinux.so open
# Standard Un*x password updating.
@include common-password
auth required pam_google_authenticator.so
Detailed scenario
I first open a reverse shell connection to a docker container running on another computer called host1 with ip xxx.xxx.xxx.xxx. The port 2222 on this computer is forwarded to port 22 in the docker container.
user1@host1:~ $ ssh -R 60001:localhost:2222 -l root -p 2222 xxx.xxx.xxx.xxx -vvvv
OpenSSH_7.9p1 Raspbian-10+deb10u3, OpenSSL 1.1.1n 15 Mar 2022
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: /etc/ssh/ssh_config line 19: Applying options for *
debug2: resolve_canonicalize: hostname xxx.xxx.xxx.xxx is address
debug2: ssh_connect_direct
debug1: Connecting to xxx.xxx.xxx.xxx [xxx.xxx.xxx.xxx] port 2222.
debug1: Connection established.
debug1: identity file /home/pi/.ssh/id_rsa type -1
debug1: identity file /home/pi/.ssh/id_rsa-cert type -1
debug1: identity file /home/pi/.ssh/id_dsa type -1
debug1: identity file /home/pi/.ssh/id_dsa-cert type -1
debug1: identity file /home/pi/.ssh/id_ecdsa type -1
debug1: identity file /home/pi/.ssh/id_ecdsa-cert type -1
debug1: identity file /home/pi/.ssh/id_ed25519 type -1
debug1: identity file /home/pi/.ssh/id_ed25519-cert type -1
debug1: identity file /home/pi/.ssh/id_xmss type -1
debug1: identity file /home/pi/.ssh/id_xmss-cert type -1
debug1: Local version string SSH-2.0-OpenSSH_7.9p1 Raspbian-10+deb10u3
debug1: Remote protocol version 2.0, remote software version OpenSSH_9.2p1 Debian-2+deb12u5
debug1: match: OpenSSH_9.2p1 Debian-2+deb12u5 pat OpenSSH* compat 0x04000000
debug2: fd 3 setting O_NONBLOCK
debug1: Authenticating to xxx.xxx.xxx.xxx:2222 as 'root'
debug3: put_host_port: [xxx.xxx.xxx.xxx]:2222
debug3: hostkeys_foreach: reading file "/home/pi/.ssh/known_hosts"
debug3: record_hostkey: found key type ECDSA in file /home/pi/.ssh/known_hosts:5
debug3: load_hostkeys: loaded 1 keys from [xxx.xxx.xxx.xxx]:2222
debug3: order_hostkeyalgs: prefer hostkeyalgs: ecdsa-sha2-nistp256-cert-v01@openssh.com,ecdsa-sha2-nistp384-cert-v01@openssh.com,ecdsa-sha2-nistp521-cert-v01@openssh.com,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521
debug3: send packet: type 20
debug1: SSH2_MSG_KEXINIT sent
debug3: receive packet: type 20
debug1: SSH2_MSG_KEXINIT received
debug2: local client KEXINIT proposal
debug2: KEX algorithms: curve25519-sha256,curve25519-sha256@libssh.org,ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group16-sha512,diffie-hellman-group18-sha512,diffie-hellman-group14-sha256,diffie-hellman-group14-sha1,ext-info-c
debug2: host key algorithms: ecdsa-sha2-nistp256-cert-v01@openssh.com,ecdsa-sha2-nistp384-cert-v01@openssh.com,ecdsa-sha2-nistp521-cert-v01@openssh.com,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,ssh-ed25519-cert-v01@openssh.com,rsa-sha2-512-cert-v01@openssh.com,rsa-sha2-256-cert-v01@openssh.com,ssh-rsa-cert-v01@openssh.com,ssh-ed25519,rsa-sha2-512,rsa-sha2-256,ssh-rsa
debug2: ciphers ctos: chacha20-poly1305@openssh.com,aes128-ctr,aes192-ctr,aes256-ctr,aes128-gcm@openssh.com,aes256-gcm@openssh.com
debug2: ciphers stoc: chacha20-poly1305@openssh.com,aes128-ctr,aes192-ctr,aes256-ctr,aes128-gcm@openssh.com,aes256-gcm@openssh.com
debug2: MACs ctos: umac-64-etm@openssh.com,umac-128-etm@openssh.com,hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com,hmac-sha1-etm@openssh.com,umac-64@openssh.com,umac-128@openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-sha1
debug2: MACs stoc: umac-64-etm@openssh.com,umac-128-etm@openssh.com,hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com,hmac-sha1-etm@openssh.com,umac-64@openssh.com,umac-128@openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-sha1
debug2: compression ctos: none,zlib@openssh.com,zlib
debug2: compression stoc: none,zlib@openssh.com,zlib
debug2: languages ctos:
debug2: languages stoc:
debug2: first_kex_follows 0
debug2: reserved 0
debug2: peer server KEXINIT proposal
debug2: KEX algorithms: sntrup761x25519-sha512,sntrup761x25519-sha512@openssh.com,curve25519-sha256,curve25519-sha256@libssh.org,ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group16-sha512,diffie-hellman-group18-sha512,diffie-hellman-group14-sha256,kex-strict-s-v00@openssh.com
debug2: host key algorithms: rsa-sha2-512,rsa-sha2-256,ecdsa-sha2-nistp256,ssh-ed25519
debug2: ciphers ctos: chacha20-poly1305@openssh.com,aes128-ctr,aes192-ctr,aes256-ctr,aes128-gcm@openssh.com,aes256-gcm@openssh.com
debug2: ciphers stoc: chacha20-poly1305@openssh.com,aes128-ctr,aes192-ctr,aes256-ctr,aes128-gcm@openssh.com,aes256-gcm@openssh.com
debug2: MACs ctos: umac-64-etm@openssh.com,umac-128-etm@openssh.com,hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com,hmac-sha1-etm@openssh.com,umac-64@openssh.com,umac-128@openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-sha1
debug2: MACs stoc: umac-64-etm@openssh.com,umac-128-etm@openssh.com,hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com,hmac-sha1-etm@openssh.com,umac-64@openssh.com,umac-128@openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-sha1
debug2: compression ctos: none,zlib@openssh.com
debug2: compression stoc: none,zlib@openssh.com
debug2: languages ctos:
debug2: languages stoc:
debug2: first_kex_follows 0
debug2: reserved 0
debug1: kex: algorithm: curve25519-sha256
debug1: kex: host key algorithm: ecdsa-sha2-nistp256
debug1: kex: server->client cipher: chacha20-poly1305@openssh.com MAC: <implicit> compression: none
debug1: kex: client->server cipher: chacha20-poly1305@openssh.com MAC: <implicit> compression: none
debug3: send packet: type 30
debug1: expecting SSH2_MSG_KENote that the scenario works when I eliminate Docker, meaning I reverse tunnel from host1 to the computer that would normally run Docker and then tunnel back from this computer to host1.X_ECDH_REPLY
debug3: receive packet: type 31
debug1: Server host key: ecdsa-sha2-nistp256 SHA256:L4f4qPemo4s2FDFsQocs8QzHJNTOUIcBOcqMynQzb8g
debug3: put_host_port: [xxx.xxx.xxx.xxx]:2222
debug3: put_host_port: [xxx.xxx.xxx.xxx]:2222
debug3: hostkeys_foreach: reading file "/home/pi/.ssh/known_hosts"
debug3: record_hostkey: found key type ECDSA in file /home/pi/.ssh/known_hosts:5
debug3: load_hostkeys: loaded 1 keys from [xxx.xxx.xxx.xxx]:2222
debug3: hostkeys_foreach: reading file "/home/pi/.ssh/known_hosts"
debug3: record_hostkey: found key type ECDSA in file /home/pi/.ssh/known_hosts:5
debug3: load_hostkeys: loaded 1 keys from [xxx.xxx.xxx.xxx]:2222
debug1: Host '[xxx.xxx.xxx.xxx]:2222' is known and matches the ECDSA host key.
debug1: Found key in /home/pi/.ssh/known_hosts:5
debug3: send packet: type 21
debug2: set_newkeys: mode 1
debug1: rekey after 134217728 blocks
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug3: receive packet: type 21
debug1: SSH2_MSG_NEWKEYS received
debug2: set_newkeys: mode 0
debug1: rekey after 134217728 blocks
debug1: Will attempt key: /home/pi/.ssh/id_rsa
debug1: Will attempt key: /home/pi/.ssh/id_dsa
debug1: Will attempt key: /home/pi/.ssh/id_ecdsa
debug1: Will attempt key: /home/pi/.ssh/id_ed25519
debug1: Will attempt key: /home/pi/.ssh/id_xmss
debug2: pubkey_prepare: done
debug3: send packet: type 5
debug3: receive packet: type 7
debug1: SSH2_MSG_EXT_INFO received
debug1: kex_input_ext_info: server-sig-algs=<ssh-ed25519,sk-ssh-ed25519@openssh.com,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,sk-ecdsa-sha2-nistp256@openssh.com,webauthn-sk-ecdsa-sha2-nistp256@openssh.com,ssh-dss,ssh-rsa,rsa-sha2-256,rsa-sha2-512>
debug1: kex_input_ext_info: publickey-hostbound@openssh.com (unrecognised)
debug3: receive packet: type 6
debug2: service_accept: ssh-userauth
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug3: send packet: type 50
debug3: receive packet: type 51
debug1: Authentications that can continue: publickey,keyboard-interactive
debug3: start over, passed a different list publickey,keyboard-interactive
debug3: preferred gssapi-keyex,gssapi-with-mic,publickey,keyboard-interactive,password
debug3: authmethod_lookup publickey
debug3: remaining preferred: keyboard-interactive,password
debug3: authmethod_is_enabled publickey
debug1: Next authentication method: publickey
debug1: Trying private key: /home/pi/.ssh/id_rsa
debug3: no such identity: /home/pi/.ssh/id_rsa: No such file or directory
debug1: Trying private key: /home/pi/.ssh/id_dsa
debug3: no such identity: /home/pi/.ssh/id_dsa: No such file or directory
debug1: Trying private key: /home/pi/.ssh/id_ecdsa
debug3: no such identity: /home/pi/.ssh/id_ecdsa: No such file or directory
debug1: Trying private key: /home/pi/.ssh/id_ed25519
debug3: no such identity: /home/pi/.ssh/id_ed25519: No such file or directory
debug1: Trying private key: /home/pi/.ssh/id_xmss
debug3: no such identity: /home/pi/.ssh/id_xmss: No such file or directory
debug2: we did not send a packet, disable method
debug3: authmethod_lookup keyboard-interactive
debug3: remaining preferred: password
debug3: authmethod_is_enabled keyboard-interactive
debug1: Next authentication method: keyboard-interactive
debug2: userauth_kbdint
debug3: send packet: type 50
debug2: we sent a keyboard-interactive packet, wait for reply
debug3: receive packet: type 60
debug2: input_userauth_info_req
debug2: input_userauth_info_req: num_prompts 1
Verification code:
debug3: send packet: type 61
debug3: receive packet: type 51
debug1: Authentications that can continue: publickey,keyboard-interactive
debug2: userauth_kbdint
debug3: send packet: type 50
debug2: we sent a keyboard-interactive packet, wait for reply
debug3: receive packet: type 60
debug2: input_userauth_info_req
debug2: input_userauth_info_req: num_prompts 1
Verification code:
debug3: send packet: type 61
debug3: receive packet: type 60
debug2: input_userauth_info_req
debug2: input_userauth_info_req: num_prompts 0
debug3: send packet: type 61
debug3: receive packet: type 52
debug1: Authentication succeeded (keyboard-interactive).
Authenticated to xxx.xxx.xxx.xxx ([xxx.xxx.xxx.xxx]:2222).
debug1: Remote connections from LOCALHOST:60001 forwarded to local address localhost:2222
debug3: send packet: type 80
debug1: channel 0: new [client-session]
debug3: ssh_session2_open: channel_new: 0
debug2: channel 0: send open
debug3: send packet: type 90
debug1: Requesting no-more-sessions@openssh.com
debug3: send packet: type 80
debug1: Entering interactive session.
debug1: pledge: network
debug3: receive packet: type 80
debug1: client_input_global_request: rtype hostkeys-00@openssh.com want_reply 0
debug3: receive packet: type 81
debug1: remote forward success for: listen 60001, connect localhost:2222
debug1: All remote forwarding requests processed
debug3: receive packet: type 91
debug2: channel_input_open_confirmation: channel 0: callback start
debug2: fd 3 setting TCP_NODELAY
debug3: ssh_packet_set_tos: set IP_TOS 0x10
debug2: client_session2_setup: id 0
debug2: channel 0: request pty-req confirm 1
debug3: send packet: type 98
debug1: Sending environment.
debug3: Ignored env SHELL
debug1: Sending env LC_ADDRESS = de_DE.UTF-8
debug2: channel 0: request env confirm 0
debug3: send packet: type 98
debug1: Sending env LC_NAME = de_DE.UTF-8
debug2: channel 0: request env confirm 0
debug3: send packet: type 98
debug1: Sending env LC_MONETARY = de_DE.UTF-8
debug2: channel 0: request env confirm 0
debug3: send packet: type 98
debug3: Ignored env PWD
debug3: Ignored env LOGNAME
debug3: Ignored env XDG_SESSION_TYPE
debug3: Ignored env HOME
debug1: Sending env LANG = en_GB.UTF-8
debug2: channel 0: request env confirm 0
debug3: send packet: type 98
debug1: Sending env LC_PAPER = de_DE.UTF-8
debug2: channel 0: request env confirm 0
debug3: send packet: type 98
debug3: Ignored env LS_COLORS
debug3: Ignored env SSH_CONNECTION
debug3: Ignored env XDG_SESSION_CLASS
debug3: Ignored env TERM
debug1: Sending env LC_IDENTIFICATION = de_DE.UTF-8
debug2: channel 0: request env confirm 0
debug3: send packet: type 98
debug3: Ignored env USER
debug3: Ignored env DISPLAY
debug3: Ignored env SHLVL
debug1: Sending env LC_TELEPHONE = de_DE.UTF-8
debug2: channel 0: request env confirm 0
debug3: send packet: type 98
debug1: Sending env LC_MEASUREMENT = de_DE.UTF-8
debug2: channel 0: request env confirm 0
debug3: send packet: type 98
debug3: Ignored env XDG_SESSION_ID
debug3: Ignored env XDG_RUNTIME_DIR
debug3: Ignored env SSH_CLIENT
debug1: Sending env LC_TIME = de_DE.UTF-8
debug2: channel 0: request env confirm 0
debug3: send packet: type 98
debug3: Ignored env PATH
debug3: Ignored env DBUS_SESSION_BUS_ADDRESS
debug3: Ignored env MAIL
debug3: Ignored env SSH_TTY
debug1: Sending env LC_NUMERIC = de_DE.UTF-8
debug2: channel 0: request env confirm 0
debug3: send packet: type 98
debug3: Ignored env TEXTDOMAIN
debug3: Ignored env _
debug2: channel 0: request shell confirm 1
debug3: send packet: type 98
debug2: channel_input_open_confirmation: channel 0: callback done
debug2: channel 0: open confirm rwindow 0 rmax 32768
debug3: receive packet: type 99
debug2: channel_input_status_confirm: type 99 id 0
debug2: PTY allocation request accepted on channel 0
debug2: channel 0: rcvd adjust 2097152
debug3: receive packet: type 99
debug2: channel_input_status_confirm: type 99 id 0
debug2: shell request accepted on channel 0
Linux 1cbc74923670 6.8.0-56-generic #58-Ubuntu SMP PREEMPT_DYNAMIC Fri Feb 14 15:33:28 UTC 2025 x86_64
The programs included with the Debian GNU/Linux system are free software;
the exact distribution terms for each program are described in the
individual files in /usr/share/doc/*/copyright.
Debian GNU/Linux comes with ABSOLUTELY NO WARRANTY, to the extent
permitted by applicable law.
Last login: Thu Apr 3 14:13:22 2025 from 10.1.1.63
root@1cbc74923670:~#
Now, I start a shell in the docker container using docker exec -it 1cbc74923670 sh and attempt to connect through the reverse tunnel to host1, which fails.
This is the output inside the container:
root@1cbc74923670:/# ssh -l pi -p 60001 localhost -vvvv
OpenSSH_9.2p1 Debian-2+deb12u5, OpenSSL 3.0.15 3 Sep 2024
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: /etc/ssh/ssh_config line 19: include /etc/ssh/ssh_config.d/*.conf matched no files
debug1: /etc/ssh/ssh_config line 21: Applying options for *
debug3: expanded UserKnownHostsFile '~/.ssh/known_hosts' -> '/root/.ssh/known_hosts'
debug3: expanded UserKnownHostsFile '~/.ssh/known_hosts2' -> '/root/.ssh/known_hosts2'
debug2: resolving "localhost" port 60001
debug3: resolve_host: lookup localhost:60001
debug3: ssh_connect_direct: entering
debug1: Connecting to localhost [::1] port 60001.
debug3: set_sock_tos: set socket 3 IPV6_TCLASS 0x10
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_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: identity file /root/.ssh/id_dsa type -1
debug1: identity file /root/.ssh/id_dsa-cert type -1
debug1: Local version string SSH-2.0-OpenSSH_9.2p1 Debian-2+deb12u5
kex_exchange_identification: read: Connection reset by peer
Connection reset by ::1 port 60001
Corresponding output on host1 during connection attempt:
debug3: receive packet: type 90
debug1: client_input_channel_open: ctype forwarded-tcpip rchan 3 win 2097152 max 32768
debug1: client_request_forwarded_tcpip: listen localhost port 60001, originator ::1 port 40146
debug2: fd 7 setting O_NONBLOCK
debug2: fd 7 setting TCP_NODELAY
debug1: connect_next: host localhost ([::1]:2222) in progress, fd=7
debug3: fd 7 is O_NONBLOCK
debug3: fd 7 is O_NONBLOCK
debug1: channel 1: new [::1]
debug1: confirm forwarded-tcpip
debug3: channel 1: waiting for connection
debug1: channel 1: connection failed: Connection refused
debug2: fd 8 setting O_NONBLOCK
debug2: fd 8 setting TCP_NODELAY
debug1: connect_next: host localhost ([127.0.0.1]:2222) in progress, fd=8
debug3: channel 1: waiting for connection
debug1: channel 1: connection failed: Connection refused
connect_to localhost port 2222: failed.
debug3: send packet: type 92
debug2: channel 1: zombie
debug2: channel 1: garbage collecting
debug1: channel 1: free: ::1, nchannels 2
debug3: channel 1: status: The following connections are open:
#0 client-session (t4 r2 i0/0 o0/0 e[write]/0 fd 4/5/6 sock -1 cc -1)