Tengo un problema extraño al conectarme y utilizar SSH en varios servidores. En puntos aleatorios de la fase de conexión, o después de estar conectado por un tiempo, la conexión se agota.
El problema aparece tanto en mi Mac como en mi iPhone (usando la aplicación Termius).
Ocurre tanto cuando se usa una clave ssh como cuando se usa una contraseña, pero más a menudo cuando se usa una clave ssh.
El problema sólo aparece cuando se utiliza Internet en la oficina. Cuando uso 4G desde mi teléfono, el problema desaparece. Usar el teléfono como punto de acceso móvil conectado al enrutador de la oficina también funciona, por lo que el problema parece estar en nuestro ISP.
He hablado con el soporte del ISP y no hay nada que puedan hacer.
Esto empezó a suceder ayer, no hubo problemas antes.
A continuación se muestra un intento de conexión cuando se utiliza una contraseña para autenticar (dirección IP, nombre de usuario anónimo):
$ ssh -vvv [email protected]
OpenSSH_8.1p1, OpenSSL 1.1.1d 10 Sep 2019
debug1: Reading configuration data /usr/local/etc/ssh/ssh_config
debug2: resolve_canonicalize: hostname 1.2.3.4 is address
debug2: ssh_connect_direct
debug1: Connecting to 1.2.3.4 [1.2.3.4] port 22.
debug1: Connection established.
debug1: identity file /Users/username/.ssh/id_rsa type -1
debug1: identity file /Users/username/.ssh/id_rsa-cert type -1
debug1: identity file /Users/username/.ssh/id_dsa type -1
debug1: identity file /Users/username/.ssh/id_dsa-cert type -1
debug1: identity file /Users/username/.ssh/id_ecdsa type -1
debug1: identity file /Users/username/.ssh/id_ecdsa-cert type -1
debug1: identity file /Users/username/.ssh/id_ed25519 type -1
debug1: identity file /Users/username/.ssh/id_ed25519-cert type -1
debug1: identity file /Users/username/.ssh/id_xmss type -1
debug1: identity file /Users/username/.ssh/id_xmss-cert type -1
debug1: Local version string SSH-2.0-OpenSSH_8.1
debug1: Remote protocol version 2.0, remote software version OpenSSH_7.2p2 Ubuntu-4ubuntu2.8
debug1: match: OpenSSH_7.2p2 Ubuntu-4ubuntu2.8 pat OpenSSH_7.0*,OpenSSH_7.1*,OpenSSH_7.2*,OpenSSH_7.3*,OpenSSH_7.4*,OpenSSH_7.5*,OpenSSH_7.6*,OpenSSH_7.7* compat 0x04000002
debug2: fd 3 setting O_NONBLOCK
debug1: Authenticating to 1.2.3.4:22 as 'user'
debug3: hostkeys_foreach: reading file "/Users/username/.ssh/known_hosts"
debug3: record_hostkey: found key type ECDSA in file /Users/username/.ssh/known_hosts:2
debug3: load_hostkeys: loaded 1 keys from 1.2.3.4
debug3: order_hostkeyalgs: prefer hostkeyalgs: [email protected],[email protected],[email protected],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,[email protected],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: [email protected],[email protected],[email protected],ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,[email protected],[email protected],[email protected],[email protected],ssh-ed25519,rsa-sha2-512,rsa-sha2-256,ssh-rsa
debug2: ciphers ctos: [email protected],aes128-ctr,aes192-ctr,aes256-ctr,[email protected],[email protected]
debug2: ciphers stoc: [email protected],aes128-ctr,aes192-ctr,aes256-ctr,[email protected],[email protected]
debug2: MACs ctos: [email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],hmac-sha2-256,hmac-sha2-512,hmac-sha1
debug2: MACs stoc: [email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],hmac-sha2-256,hmac-sha2-512,hmac-sha1
debug2: compression ctos: none,[email protected],zlib
debug2: compression stoc: none,[email protected],zlib
debug2: languages ctos:
debug2: languages stoc:
debug2: first_kex_follows 0
debug2: reserved 0
debug2: peer server KEXINIT proposal
debug2: KEX algorithms: [email protected],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: [email protected],aes128-ctr,aes192-ctr,aes256-ctr,[email protected],[email protected]
debug2: ciphers stoc: [email protected],aes128-ctr,aes192-ctr,aes256-ctr,[email protected],[email protected]
debug2: MACs ctos: [email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],hmac-sha2-256,hmac-sha2-512,hmac-sha1
debug2: MACs stoc: [email protected],[email protected],[email protected],[email protected],[email protected],[email protected],[email protected],hmac-sha2-256,hmac-sha2-512,hmac-sha1
debug2: compression ctos: none,[email protected]
debug2: compression stoc: none,[email protected]
debug2: languages ctos:
debug2: languages stoc:
debug2: first_kex_follows 0
debug2: reserved 0
debug1: kex: algorithm: [email protected]
debug1: kex: host key algorithm: ecdsa-sha2-nistp256
debug1: kex: server->client cipher: [email protected] MAC: <implicit> compression: none
debug1: kex: client->server cipher: [email protected] 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:aTTwsnW7RYumH3f5rR0UqAsvZM5F2tgP1XQY33CZhTQ
debug3: hostkeys_foreach: reading file "/Users/username/.ssh/known_hosts"
debug3: record_hostkey: found key type ECDSA in file /Users/username/.ssh/known_hosts:2
debug3: load_hostkeys: loaded 1 keys from 1.2.3.4
debug1: Host '1.2.3.4' is known and matches the ECDSA host key.
debug1: Found key in /Users/username/.ssh/known_hosts:2
debug3: send packet: type 21
debug2: set_newkeys: mode 1
debug1: rekey out 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 in after 134217728 blocks
debug1: Will attempt key: /Users/username/.ssh/id_rsa
debug1: Will attempt key: /Users/username/.ssh/id_dsa
debug1: Will attempt key: /Users/username/.ssh/id_ecdsa
debug1: Will attempt key: /Users/username/.ssh/id_ed25519
debug1: Will attempt key: /Users/username/.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=<rsa-sha2-256,rsa-sha2-512>
ssh_dispatch_run_fatal: Connection to 1.2.3.4 port 22: Operation timed out
No aparece nada en los registros de los servidores.
Respuesta1
Estos problemas suelen deberse a una discrepancia en la MTU.