ssh login gets stuck at "expecting SSH2_MSG_KEX_ECDH_REPLY" at random.
However forcing ssh to use 3des cipher suite makes the login go through. What causes the login to succeed when cipher suite is forced but fail otherwise ? Here are the debug for 3 different use cases: 1) successful login attempt 2) failed login attempt 3) forced 3des cipher suite ============================================================================== 1) Successful login attempt ============================================================================== -bash-4.1$ ssh -vvv root@wsbmc011 OpenSSH_5.8p2, OpenSSL 1.0.0g 18 Jan 2012 debug1: Reading configuration data /gsa/ausgsa/projects/i/indiateam04/hramasub/.ssh/config debug1: Reading configuration data /etc/ssh/ssh_config debug1: Applying options for * debug2: ssh_connect: needpriv 0 debug1: Connecting to wsbmc011 [9.3.21.42] port 22. debug1: Connection established. debug3: Incorrect RSA1 identifier debug3: Could not load "/gsa/ausgsa/projects/i/indiateam04/hramasub/.ssh/id_rsa" as a RSA1 public key debug2: key_type_from_name: unknown key type '-----BEGIN' debug3: key_read: missing keytype debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug3: key_read: missing whitespace debug2: key_type_from_name: unknown key type '-----END' debug3: key_read: missing keytype debug1: identity file /gsa/ausgsa/projects/i/indiateam04/hramasub/.ssh/id_rsa type 1 debug1: identity file /gsa/ausgsa/projects/i/indiateam04/hramasub/.ssh/id_rsa-cert type -1 debug1: identity file /gsa/ausgsa/projects/i/indiateam04/hramasub/.ssh/id_dsa type -1 debug1: identity file /gsa/ausgsa/projects/i/indiateam04/hramasub/.ssh/id_dsa-cert type -1 debug1: identity file /gsa/ausgsa/projects/i/indiateam04/hramasub/.ssh/id_ecdsa type -1 debug1: identity file /gsa/ausgsa/projects/i/indiateam04/hramasub/.ssh/id_ecdsa-cert type -1 debug1: Remote protocol version 2.0, remote software version dropbear_2016.74 debug1: no match: dropbear_2016.74 debug1: Enabling compatibility mode for protocol 2.0 debug1: Local version string SSH-2.0-OpenSSH_5.8 debug2: fd 3 setting O_NONBLOCK debug3: load_hostkeys: loading entries for host "wsbmc011" from file "/gsa/ausgsa/projects/i/indiateam04/hramasub/.ssh/known_hosts" debug3: load_hostkeys: found key type RSA in file /gsa/ausgsa/projects/i/indiateam04/hramasub/.ssh/known_hosts:23 debug3: load_hostkeys: loaded 1 keys debug3: order_hostkeyalgs: prefer hostkeyalgs: ssh-rsa-cert-...@openssh.com,ssh-rsa-cert-...@openssh.com,ssh-rsa debug1: SSH2_MSG_KEXINIT sent debug1: SSH2_MSG_KEXINIT received debug2: kex_parse_kexinit: ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha1,diffie-hellman-group1-sha1 debug2: kex_parse_kexinit: ssh-rsa-cert-...@openssh.com,ssh-rsa-cert-...@openssh.com,ssh-rsa,ecdsa-sha2-nistp256-cert-...@openssh.com,ecdsa-sha2-nistp384-cert-...@openssh.com,ecdsa-sha2-nistp521-cert-...@openssh.com,ssh-dss-cert-v01@openssh .com,ssh-dss-cert-...@openssh.com,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa- sha2-nistp521,ssh-dss debug2: kex_parse_kexinit: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,rijndael-...@lysator.liu.se debug2: kex_parse_kexinit: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,rijndael-...@lysator.liu.se debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,umac...@openssh.com,hmac-ripemd160,hmac-ripemd...@openssh.com,hmac-sha1-96,hmac-md5-96 debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,umac...@openssh.com,hmac-ripemd160,hmac-ripemd...@openssh.com,hmac-sha1-96,hmac-md5-96 debug2: kex_parse_kexinit: none,z...@openssh.com,zlib debug2: kex_parse_kexinit: none,z...@openssh.com,zlib debug2: kex_parse_kexinit: debug2: kex_parse_kexinit: debug2: kex_parse_kexinit: first_kex_follows 0 debug2: kex_parse_kexinit: reserved 0 debug2: kex_parse_kexinit: curve25519-sha...@libssh.org,ecdh-sha2-nistp521,ecdh-sha2-nistp384,ecdh-sha2-nistp256,diffie-hellman-group14-sha1,diffie-hellman-group1-sha1,kexgue...@matt.ucc.asn.au debug2: kex_parse_kexinit: ssh-rsa debug2: kex_parse_kexinit: aes128-ctr,aes256-ctr,aes128-cbc,aes256-cbc,twofish256-cbc,twofish-cbc,twofish128-cbc,3des-ctr,3des-cbc debug2: kex_parse_kexinit: aes128-ctr,aes256-ctr,aes128-cbc,aes256-cbc,twofish256-cbc,twofish-cbc,twofish128-cbc,3des-ctr,3des-cbc debug2: kex_parse_kexinit: hmac-sha1-96,hmac-sha1,hmac-sha2-256,hmac-sha2-512,hmac-md5 debug2: kex_parse_kexinit: hmac-sha1-96,hmac-sha1,hmac-sha2-256,hmac-sha2-512,hmac-md5 debug2: kex_parse_kexinit: z...@openssh.com,none debug2: kex_parse_kexinit: z...@openssh.com,none debug2: kex_parse_kexinit: debug2: kex_parse_kexinit: debug2: kex_parse_kexinit: first_kex_follows 0 debug2: kex_parse_kexinit: reserved 0 debug2: mac_setup: found hmac-md5 debug1: kex: server->client aes128-ctr hmac-md5 none debug2: mac_setup: found hmac-md5 debug1: kex: client->server aes128-ctr hmac-md5 none debug1: sending SSH2_MSG_KEX_ECDH_INIT debug1: expecting SSH2_MSG_KEX_ECDH_REPLY debug1: Server host key: RSA 70:28:98:8f:c1:8b:0e:33:a2:cc:e5:3d:c3:d0:f3:82 debug3: load_hostkeys: loading entries for host "wsbmc011" from file "/gsa/ausgsa/projects/i/indiateam04/hramasub/.ssh/known_hosts" debug3: load_hostkeys: found key type RSA in file /gsa/ausgsa/projects/i/indiateam04/hramasub/.ssh/known_hosts:23 debug3: load_hostkeys: loaded 1 keys debug3: load_hostkeys: loading entries for host "9.3.21.42" from file "/gsa/ausgsa/projects/i/indiateam04/hramasub/.ssh/known_hosts" debug3: load_hostkeys: found key type RSA in file /gsa/ausgsa/projects/i/indiateam04/hramasub/.ssh/known_hosts:15 debug3: load_hostkeys: loaded 1 keys debug1: Host 'wsbmc011' is known and matches the RSA host key. debug1: Found key in /gsa/ausgsa/projects/i/indiateam04/hramasub/.ssh/known_hosts:23 debug1: ssh_rsa_verify: signature correct debug2: kex_derive_keys debug2: set_newkeys: mode 1 debug1: SSH2_MSG_NEWKEYS sent debug1: expecting SSH2_MSG_NEWKEYS debug2: set_newkeys: mode 0 debug1: SSH2_MSG_NEWKEYS received debug1: Roaming not allowed by server debug1: SSH2_MSG_SERVICE_REQUEST sent debug2: service_accept: ssh-userauth debug1: SSH2_MSG_SERVICE_ACCEPT received debug2: key: /gsa/ausgsa/projects/i/indiateam04/hramasub/.ssh/id_rsa (0x9dd410) debug2: key: /gsa/ausgsa/projects/i/indiateam04/hramasub/.ssh/id_dsa ((nil)) debug2: key: /gsa/ausgsa/projects/i/indiateam04/hramasub/.ssh/id_ecdsa ((nil)) debug1: Authentications that can continue: publickey,password debug3: start over, passed a different list publickey,password 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: /gsa/ausgsa/projects/i/indiateam04/hramasub/.ssh/id_rsa debug3: send_pubkey_test debug2: we sent a publickey packet, wait for reply debug1: Authentications that can continue: publickey,password debug1: Trying private key: /gsa/ausgsa/projects/i/indiateam04/hramasub/.ssh/id_dsa debug3: no such identity: /gsa/ausgsa/projects/i/indiateam04/hramasub/.ssh/id_dsa debug1: Trying private key: /gsa/ausgsa/projects/i/indiateam04/hramasub/.ssh/id_ecdsa debug3: no such identity: /gsa/ausgsa/projects/i/indiateam04/hramasub/.ssh/id_ecdsa debug2: we did not send a packet, disable method debug3: authmethod_lookup password debug3: remaining preferred: ,password debug3: authmethod_is_enabled password debug1: Next authentication method: password root@wsbmc011's password: ============================================================================== 2) failed login attempt ============================================================================== $ ssh -v root@wsbmc011 OpenSSH_5.8p2, OpenSSL 1.0.0g 18 Jan 2012 debug1: Reading configuration data /gsa/ausgsa/projects/i/indiateam04/gkeishin/.ssh/config debug1: Reading configuration data /etc/ssh/ssh_config debug1: Applying options for * debug1: Connecting to wsbmc011 [9.3.21.42] port 22. debug1: Connection established. debug1: identity file /gsa/ausgsa/projects/i/indiateam04/gkeishin/.ssh/id_rsa type 1 debug1: identity file /gsa/ausgsa/projects/i/indiateam04/gkeishin/.ssh/id_rsa-cert type -1 debug1: identity file /gsa/ausgsa/projects/i/indiateam04/gkeishin/.ssh/id_dsa type -1 debug1: identity file /gsa/ausgsa/projects/i/indiateam04/gkeishin/.ssh/id_dsa-cert type -1 debug1: identity file /gsa/ausgsa/projects/i/indiateam04/gkeishin/.ssh/id_ecdsa type -1 debug1: identity file /gsa/ausgsa/projects/i/indiateam04/gkeishin/.ssh/id_ecdsa-cert type -1 debug1: Remote protocol version 2.0, remote software version dropbear_2016.74 debug1: no match: dropbear_2016.74 debug1: Enabling compatibility mode for protocol 2.0 debug1: Local version string SSH-2.0-OpenSSH_5.8 debug1: SSH2_MSG_KEXINIT sent debug1: SSH2_MSG_KEXINIT received debug1: kex: server->client aes128-ctr hmac-md5 none debug1: kex: client->server aes128-ctr hmac-md5 none debug1: sending SSH2_MSG_KEX_ECDH_INIT debug1: expecting SSH2_MSG_KEX_ECDH_REPLY ============================================================================== 3) forced 3des cipher suite ============================================================================== $ ssh -c 3des -v root@wsbmc011 OpenSSH_5.8p2, OpenSSL 1.0.0g 18 Jan 2012 debug1: Reading configuration data /gsa/ausgsa/projects/i/indiateam04/gkeishin/.ssh/config debug1: Reading configuration data /etc/ssh/ssh_config debug1: Applying options for * debug1: Connecting to wsbmc011 [9.3.21.42] port 22. debug1: Connection established. debug1: identity file /gsa/ausgsa/projects/i/indiateam04/gkeishin/.ssh/id_rsa type 1 debug1: identity file /gsa/ausgsa/projects/i/indiateam04/gkeishin/.ssh/id_rsa-cert type -1 debug1: identity file /gsa/ausgsa/projects/i/indiateam04/gkeishin/.ssh/id_dsa type -1 debug1: identity file /gsa/ausgsa/projects/i/indiateam04/gkeishin/.ssh/id_dsa-cert type -1 debug1: identity file /gsa/ausgsa/projects/i/indiateam04/gkeishin/.ssh/id_ecdsa type -1 debug1: identity file /gsa/ausgsa/projects/i/indiateam04/gkeishin/.ssh/id_ecdsa-cert type -1 debug1: Remote protocol version 2.0, remote software version dropbear_2016.74 debug1: no match: dropbear_2016.74 debug1: Enabling compatibility mode for protocol 2.0 debug1: Local version string SSH-2.0-OpenSSH_5.8 debug1: SSH2_MSG_KEXINIT sent debug1: SSH2_MSG_KEXINIT received debug1: kex: server->client 3des-cbc hmac-md5 none debug1: kex: client->server 3des-cbc hmac-md5 none debug1: sending SSH2_MSG_KEX_ECDH_INIT debug1: expecting SSH2_MSG_KEX_ECDH_REPLY debug1: Server host key: RSA 70:28:98:8f:c1:8b:0e:33:a2:cc:e5:3d:c3:d0:f3:82 debug1: Host 'wsbmc011' is known and matches the RSA host key. debug1: Found key in /gsa/ausgsa/projects/i/indiateam04/gkeishin/.ssh/known_hosts:26 debug1: ssh_rsa_verify: signature correct debug1: SSH2_MSG_NEWKEYS sent debug1: expecting SSH2_MSG_NEWKEYS debug1: SSH2_MSG_NEWKEYS received debug1: Roaming not allowed by server debug1: SSH2_MSG_SERVICE_REQUEST sent debug1: SSH2_MSG_SERVICE_ACCEPT received debug1: Authentications that can continue: publickey,password debug1: Next authentication method: publickey debug1: Offering RSA public key: /gsa/ausgsa/projects/i/indiateam04/gkeishin/.ssh/id_rsa debug1: Authentications that can continue: publickey,password debug1: Trying private key: /gsa/ausgsa/projects/i/indiateam04/gkeishin/.ssh/id_dsa debug1: Trying private key: /gsa/ausgsa/projects/i/indiateam04/gkeishin/.ssh/id_ecdsa debug1: Next authentication method: password root@wsbmc011's password: Thanks in advance, Hari ! Hariharasubramanian R. Power Firmware Development IBM India Systems & Technology Lab, Bangalore, India Phone: +91 80 4025 6950