Hello we have a dropbear version 2020,81 running in an old release of our SW as our login server. Currently we experience issues logging in on the system from the remote system running Openssh (using dropbear also on the client side we see a similar result).
At the end of the mail I pasted the output we get. (after the trace "debug1: expecting SSH2_MSG_KEX_ECDH_REPLY", nothing is seen anymore) This issue is not seen persistently and seems to occur on random systems. After a reboot the issue seems to be resolved, not clear whether it will come back after some time or not. For the moment it is impossible to collect local traces on the server node since we cannot reach it anymore. Doing a telnet to the port 2222 is actually showing the dropbear version etc, meaning that the connection as such (at TCP level) seems to be OK. Is this a known issue and is there something we can do as a workaround (or do we have means to collect more information about the root cause)? Thanks. Best regards, Ronny ~ # ssh -p 2222 root@169.254.1.4 -vvvv OpenSSH_8.4p1, OpenSSL 1.1.1j 16 Feb 2021 debug1: Reading configuration data /etc/ssh/ssh_config debug2: resolve_canonicalize: hostname 169.254.1.4 is address debug3: expanded UserKnownHostsFile '~/.ssh/known_hosts' -> '/root/.ssh/known_hosts' debug3: expanded UserKnownHostsFile '~/.ssh/known_hosts2' -> '/root/.ssh/known_hosts2' debug1: Authenticator provider $SSH_SK_PROVIDER did not resolve; disabling debug2: ssh_connect_direct debug1: Connecting to 169.254.1.4 [169.254.1.4] port 2222. 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_8.4 debug1: Remote protocol version 2.0, remote software version dropbear_2020.81 debug1: no match: dropbear_2020.81 debug2: fd 3 setting O_NONBLOCK debug1: Authenticating to 169.254.1.4:2222 as 'root' debug3: put_host_port: [169.254.1.4]:2222 debug3: hostkeys_foreach: reading file "/root/.ssh/known_hosts" 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-sha...@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,ext-info-c debug2: host key algorithms: ecdsa-sha2-nistp256-cert-...@openssh.com,ecdsa-sha2-nistp384-cert-...@openssh.com,ecdsa-sha2-nistp521-cert-...@openssh.com,sk-ecdsa-sha2-nistp256-cert-...@openssh.com,ssh-ed25519-cert-...@openssh.com,sk-ssh-ed25519-cert-...@openssh.com,rsa-sha2-512-cert-...@openssh.com,rsa-sha2-256-cert-...@openssh.com,ssh-rsa-cert-...@openssh.com,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,sk-ecdsa-sha2-nistp...@openssh.com,ssh-ed25519,sk-ssh-ed25...@openssh.com,rsa-sha2-512,rsa-sha2-256,ssh-rsa debug2: ciphers ctos: chacha20-poly1...@openssh.com,aes128-ctr,aes192-ctr,aes256-ctr,aes128-...@openssh.com,aes256-...@openssh.com debug2: ciphers stoc: chacha20-poly1...@openssh.com,aes128-ctr,aes192-ctr,aes256-ctr,aes128-...@openssh.com,aes256-...@openssh.com debug2: MACs ctos: umac-64-...@openssh.com,umac-128-...@openssh.com,hmac-sha2-256-...@openssh.com,hmac-sha2-512-...@openssh.com,hmac-sha1-...@openssh.com,umac...@openssh.com,umac-...@openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-sha1 debug2: MACs stoc: umac-64-...@openssh.com,umac-128-...@openssh.com,hmac-sha2-256-...@openssh.com,hmac-sha2-512-...@openssh.com,hmac-sha1-...@openssh.com,umac...@openssh.com,umac-...@openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-sha1 debug2: compression ctos: none,z...@openssh.com,zlib debug2: compression stoc: none,z...@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: curve25519-sha256,curve25519-sha...@libssh.org,ecdh-sha2-nistp521,ecdh-sha2-nistp384,ecdh-sha2-nistp256,diffie-hellman-group14-sha256,diffie-hellman-group14-sha1,kexgue...@matt.ucc.asn.au debug2: host key algorithms: ssh-ed25519,ecdsa-sha2-nistp256,rsa-sha2-256,ssh-rsa debug2: ciphers ctos: chacha20-poly1...@openssh.com,aes128-ctr,aes256-ctr debug2: ciphers stoc: chacha20-poly1...@openssh.com,aes128-ctr,aes256-ctr debug2: MACs ctos: hmac-sha1,hmac-sha2-256 debug2: MACs stoc: hmac-sha1,hmac-sha2-256 debug2: compression ctos: z...@openssh.com,none debug2: compression stoc: z...@openssh.com,none 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-poly1...@openssh.com MAC: <implicit> compression: none debug1: kex: client->server cipher: chacha20-poly1...@openssh.com MAC: <implicit> compression: none debug3: send packet: type 30 debug1: expecting SSH2_MSG_KEX_ECDH_REPLY
