I have installed Ubuntu Server 16.04 32-bit on my old notebook wirelly connected to internet (external IP). Since the beginning I've added ufw and Fail2ban. But then I discovered after a reboot I was not able to ssh into the server remotely.
After lots of attempts I could finally understand that it was not because I set up exceptions on Fail2ban or because I disable ufw the ssh server accepts remote connections again (temporarily, until next reboot).
What is hapenning in my case is that ssh starts to answer only after a local login to the server.
Any suggestion? Something related to the encryption of my user directory, perhaps?
SERVER AUTH.LOG
Feb 11 14:18:16 servername systemd-logind[1274]: System is rebooting.
Feb 11 14:19:14 servername CRON[1311]: pam_unix(cron:session): session opened for user root by (uid=0)
Feb 11 14:19:14 servername su[1374]: Successful su for noip by root
Feb 11 14:19:14 servername su[1374]: + ??? root:noip
Feb 11 14:19:14 servername su[1374]: pam_unix(su:session): session opened for user noip by (uid=0)
Feb 11 14:19:15 servername systemd-logind[1331]: New seat seat0.
Feb 11 14:19:15 servername systemd-logind[1331]: Watching system buttons on /dev/input/event3 (Power Button)
Feb 11 14:19:15 servername systemd-logind[1331]: Watching system buttons on /dev/input/event5 (Video Bus)
Feb 11 14:19:15 servername systemd-logind[1331]: Watching system buttons on /dev/input/event0 (Power Button)
Feb 11 14:19:15 servername systemd-logind[1331]: Watching system buttons on /dev/input/event1 (Lid Switch)
Feb 11 14:19:15 servername systemd-logind[1331]: Watching system buttons on /dev/input/event2 (Sleep Button)
Feb 11 14:19:15 servername systemd-logind[1331]: Watching system buttons on /dev/input/event9 (HP WMI hotkeys)
Feb 11 14:19:15 servername systemd: pam_unix(systemd-user:session): session opened for user noip by (uid=0)
Feb 11 14:19:15 servername systemd-logind[1331]: New session 1 of user noip.
Feb 11 14:19:15 servername su[1374]: pam_unix(su:session): session closed for user noip
Feb 11 14:19:16 servername sshd[1287]: Server listening on 0.0.0.0 port 22.
Feb 11 14:19:16 servername CRON[1311]: pam_unix(cron:session): session closed for user root
Feb 11 14:19:16 servername systemd-logind[1331]: Removed session 1.
Feb 11 14:19:16 servername systemd: pam_unix(systemd-user:session): session closed for user noip
Feb 11 14:19:44 servername sshd[1860]: Connection closed by x.x.x.x port 49743 [preauth]
Feb 11 14:20:01 servername login[1863]: pam_ecryptfs: Passphrase file wrapped
Feb 11 14:20:03 servername login[1410]: pam_unix(login:session): session opened for user noliva by LOGIN(uid=0)
Feb 11 14:20:03 servername systemd: pam_unix(systemd-user:session): session opened for user noliva by (uid=0)
Feb 11 14:20:03 servername systemd-logind[1331]: New session 2 of user noliva.
Feb 11 14:20:12 servername sshd[1942]: Accepted publickey for noliva from x.x.x.x port 49744 ssh2: RSA SHA256:yyyy
Feb 11 14:20:12 servername sshd[1942]: pam_unix(sshd:session): session opened for user noliva by (uid=0)
Feb 11 14:20:12 servername systemd-logind[1331]: New session 3 of user noliva.
Feb 11 14:20:25 servername sudo: noliva : TTY=pts/0 ; PWD=/home/noliva ; USER=root ; COMMAND=/usr/bin/vi /var/log/auth.log
CLIENT, BEFORE LOCAL LOGIN TO THE SERVER:
iMac-de-noliva:log noliva$ ssh -v -v -v noliva@x.x.x.x
OpenSSH_7.3p1, LibreSSL 2.4.1
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: /etc/ssh/ssh_config line 20: Applying options for *
debug2: resolving "x.x.x.x" port 22
debug2: ssh_connect_direct: needpriv 0
debug1: Connecting to x.x.x.x [x.x.x.x] port 22.
debug1: Connection established.
debug1: identity file /Users/noliva/.ssh/id_rsa type 1
debug1: key_load_public: No such file or directory
debug1: identity file /Users/noliva/.ssh/id_rsa-cert type -1
debug1: key_load_public: No such file or directory
debug1: identity file /Users/noliva/.ssh/id_dsa type -1
debug1: key_load_public: No such file or directory
debug1: identity file /Users/noliva/.ssh/id_dsa-cert type -1
debug1: key_load_public: No such file or directory
debug1: identity file /Users/noliva/.ssh/id_ecdsa type -1
debug1: key_load_public: No such file or directory
debug1: identity file /Users/noliva/.ssh/id_ecdsa-cert type -1
debug1: key_load_public: No such file or directory
debug1: identity file /Users/noliva/.ssh/id_ed25519 type -1
debug1: key_load_public: No such file or directory
debug1: identity file /Users/noliva/.ssh/id_ed25519-cert type -1
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_7.3
debug1: Remote protocol version 2.0, remote software version OpenSSH_7.2p2 Ubuntu-4ubuntu2.1
debug1: match: OpenSSH_7.2p2 Ubuntu-4ubuntu2.1 pat OpenSSH* compat 0x04000000
debug2: fd 3 setting O_NONBLOCK
debug1: Authenticating to x.x.x.x:22 as 'noliva'
debug3: hostkeys_foreach: reading file "/Users/noliva/.ssh/known_hosts"
debug3: record_hostkey: found key type ECDSA in file /Users/noliva/.ssh/known_hosts:6
debug3: load_hostkeys: loaded 1 keys from x.x.x.x
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@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-group-exchange-sha1,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,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,aes128-cbc,aes192-cbc,aes256-cbc,3des-cbc
debug2: ciphers stoc: chacha20-poly1305@openssh.com,aes128-ctr,aes192-ctr,aes256-ctr,aes128-gcm@openssh.com,aes256-gcm@openssh.com,aes128-cbc,aes192-cbc,aes256-cbc,3des-cbc
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: curve25519-sha256@libssh.org,ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group14-sha1
debug2: host key algorithms: ssh-rsa,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@libssh.org
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_KEX_ECDH_REPLY
debug3: receive packet: type 31
debug1: Server host key: ecdsa-sha2-nistp256 SHA256:5KVog8lQVx18HDJnyjAqJTIyjfkbomRD75l817SPDXs
debug3: hostkeys_foreach: reading file "/Users/noliva/.ssh/known_hosts"
debug3: record_hostkey: found key type ECDSA in file /Users/noliva/.ssh/known_hosts:6
debug3: load_hostkeys: loaded 1 keys from x.x.x.x
debug1: Host 'x.x.x.x' is known and matches the ECDSA host key.
debug1: Found key in /Users/noliva/.ssh/known_hosts:6
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
debug2: set_newkeys: mode 0
debug1: rekey after 134217728 blocks
debug1: SSH2_MSG_NEWKEYS received
debug2: key: /Users/noliva/.ssh/id_rsa (0x7f94cf7000a0)
debug2: key: /Users/noliva/.ssh/id_dsa (0x0)
debug2: key: /Users/noliva/.ssh/id_ecdsa (0x0)
debug2: key: /Users/noliva/.ssh/id_ed25519 (0x0)
debug3: send packet: type 5
debug3: receive packet: type 7
debug1: SSH2_MSG_EXT_INFO received
debug1: kex_input_ext_info: server-sig-algs=<rsa-sha2-256,rsa-sha2-512>
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
debug3: start over, passed a different list publickey
debug3: preferred 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: Offering RSA public key: /Users/noliva/.ssh/id_rsa
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: /Users/noliva/.ssh/id_dsa
debug3: no such identity: /Users/noliva/.ssh/id_dsa: No such file or directory
debug1: Trying private key: /Users/noliva/.ssh/id_ecdsa
debug3: no such identity: /Users/noliva/.ssh/id_ecdsa: No such file or directory
debug1: Trying private key: /Users/noliva/.ssh/id_ed25519
debug3: no such identity: /Users/noliva/.ssh/id_ed25519: No such file or directory
debug2: we did not send a packet, disable method
debug1: No more authentication methods to try.
Permission denied (publickey).
CLIENT, AFTER LOCAL LOGIN TO THE SERVER:
iMac-de-noliva:log noliva$ ssh -v -v -v noliva@x.x.x.x
OpenSSH_7.3p1, LibreSSL 2.4.1
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: /etc/ssh/ssh_config line 20: Applying options for *
debug2: resolving "x.x.x.x" port 22
debug2: ssh_connect_direct: needpriv 0
debug1: Connecting to x.x.x.x [x.x.x.x] port 22.
debug1: Connection established.
debug1: identity file /Users/noliva/.ssh/id_rsa type 1
debug1: key_load_public: No such file or directory
debug1: identity file /Users/noliva/.ssh/id_rsa-cert type -1
debug1: key_load_public: No such file or directory
debug1: identity file /Users/noliva/.ssh/id_dsa type -1
debug1: key_load_public: No such file or directory
debug1: identity file /Users/noliva/.ssh/id_dsa-cert type -1
debug1: key_load_public: No such file or directory
debug1: identity file /Users/noliva/.ssh/id_ecdsa type -1
debug1: key_load_public: No such file or directory
debug1: identity file /Users/noliva/.ssh/id_ecdsa-cert type -1
debug1: key_load_public: No such file or directory
debug1: identity file /Users/noliva/.ssh/id_ed25519 type -1
debug1: key_load_public: No such file or directory
debug1: identity file /Users/noliva/.ssh/id_ed25519-cert type -1
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_7.3
debug1: Remote protocol version 2.0, remote software version OpenSSH_7.2p2 Ubuntu-4ubuntu2.1
debug1: match: OpenSSH_7.2p2 Ubuntu-4ubuntu2.1 pat OpenSSH* compat 0x04000000
debug2: fd 3 setting O_NONBLOCK
debug1: Authenticating to x.x.x.x:22 as 'noliva'
debug3: hostkeys_foreach: reading file "/Users/noliva/.ssh/known_hosts"
debug3: record_hostkey: found key type ECDSA in file /Users/noliva/.ssh/known_hosts:6
debug3: load_hostkeys: loaded 1 keys from x.x.x.x
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@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-group-exchange-sha1,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,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,aes128-cbc,aes192-cbc,aes256-cbc,3des-cbc
debug2: ciphers stoc: chacha20-poly1305@openssh.com,aes128-ctr,aes192-ctr,aes256-ctr,aes128-gcm@openssh.com,aes256-gcm@openssh.com,aes128-cbc,aes192-cbc,aes256-cbc,3des-cbc
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: curve25519-sha256@libssh.org,ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group14-sha1
debug2: host key algorithms: ssh-rsa,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@libssh.org
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_KEX_ECDH_REPLY
debug3: receive packet: type 31
debug1: Server host key: ecdsa-sha2-nistp256 SHA256:5KVog8lQVx18HDJnyjAqJTIyjfkbomRD75l817SPDXs
debug3: hostkeys_foreach: reading file "/Users/noliva/.ssh/known_hosts"
debug3: record_hostkey: found key type ECDSA in file /Users/noliva/.ssh/known_hosts:6
debug3: load_hostkeys: loaded 1 keys from x.x.x.x
debug1: Host 'x.x.x.x' is known and matches the ECDSA host key.
debug1: Found key in /Users/noliva/.ssh/known_hosts:6
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
debug2: set_newkeys: mode 0
debug1: rekey after 134217728 blocks
debug1: SSH2_MSG_NEWKEYS received
debug2: key: /Users/noliva/.ssh/id_rsa (0x7fbebf420020)
debug2: key: /Users/noliva/.ssh/id_dsa (0x0)
debug2: key: /Users/noliva/.ssh/id_ecdsa (0x0)
debug2: key: /Users/noliva/.ssh/id_ed25519 (0x0)
debug3: send packet: type 5
debug3: receive packet: type 7
debug1: SSH2_MSG_EXT_INFO received
debug1: kex_input_ext_info: server-sig-algs=<rsa-sha2-256,rsa-sha2-512>
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
debug3: start over, passed a different list publickey
debug3: preferred 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: Offering RSA public key: /Users/noliva/.ssh/id_rsa
debug3: send_pubkey_test
debug3: send packet: type 50
debug2: we sent a publickey packet, wait for reply
debug3: receive packet: type 60
debug1: Server accepts key: pkalg rsa-sha2-512 blen 279
debug2: input_userauth_pk_ok: fp SHA256:yyyyy
debug3: sign_and_send_pubkey: RSA SHA256:xxxxx
Enter passphrase for key '/Users/noliva/.ssh/id_rsa':
