问题
Yesterday I reinstalled my Ubuntu (for unrelated reasons) and since then ssh behaves very weirdly.
It takes suuuper long to connect (multiple minutes). Using -vvv I found that it first tries to connect using an ipv6 (which times out) and after that tries to connect via ipv4 which works almost instantly.
I never had any issues with ssh before.
running
ssh login@address.net -vvv
(with the address I want to connect to) returns
OpenSSH_8.2p1 Ubuntu-4, OpenSSL 1.1.1f 31 Mar 2020
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 *
debug2: resolving "address.net" port 22
debug2: ssh_connect_direct
debug1: Connecting to address.net [*:*:*:*::*] port 22.
debug1: connect to address *:*:*:*::* port 22: Connection timed out
debug1: Connecting to address.net [*.*.*.*] port 22.
debug1: Connection established.
debug1: identity file /home/malte/.ssh/id_rsa type 0
debug1: identity file /home/malte/.ssh/id_rsa-cert type -1
debug1: identity file /home/malte/.ssh/id_dsa type -1
debug1: identity file /home/malte/.ssh/id_dsa-cert type -1
debug1: identity file /home/malte/.ssh/id_ecdsa type -1
debug1: identity file /home/malte/.ssh/id_ecdsa-cert type -1
debug1: identity file /home/malte/.ssh/id_ecdsa_sk type -1
debug1: identity file /home/malte/.ssh/id_ecdsa_sk-cert type -1
debug1: identity file /home/malte/.ssh/id_ed25519 type -1
debug1: identity file /home/malte/.ssh/id_ed25519-cert type -1
debug1: identity file /home/malte/.ssh/id_ed25519_sk type -1
debug1: identity file /home/malte/.ssh/id_ed25519_sk-cert type -1
debug1: identity file /home/malte/.ssh/id_xmss type -1
debug1: identity file /home/malte/.ssh/id_xmss-cert type -1
debug1: Local version string SSH-2.0-OpenSSH_8.2p1 Ubuntu-4
debug1: Remote protocol version 2.0, remote software version OpenSSH_7.6p1 Ubuntu-4ubuntu0.3
debug1: match: OpenSSH_7.6p1 Ubuntu-4ubuntu0.3 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 login.caps.in.tum.de:22 as 'ehren'
debug3: hostkeys_foreach: reading file "/home/malte/.ssh/known_hosts"
debug3: record_hostkey: found key type ED25519 in file /home/malte/.ssh/known_hosts:1
debug3: load_hostkeys: loaded 1 keys from login.caps.in.tum.de
debug3: order_hostkeyalgs: prefer hostkeyalgs: ssh-ed25519-cert-v01@openssh.com,ssh-ed25519
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,ext-info-c
debug2: host key algorithms: ssh-ed25519-cert-v01@openssh.com,ssh-ed25519,ecdsa-sha2-nistp256-cert-v01@openssh.com,ecdsa-sha2-nistp384-cert-v01@openssh.com,ecdsa-sha2-nistp521-cert-v01@openssh.com,sk-ecdsa-sha2-nistp256-cert-v01@openssh.com,sk-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,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,sk-ecdsa-sha2-nistp256@openssh.com,sk-ssh-ed25519@openssh.com,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: 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
debug2: host key algorithms: ssh-rsa,rsa-sha2-512,rsa-sha2-256,ecdsa-sha2-nistp256,ssh-ed25519,ssh-ed25519-cert-v01@openssh.com
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: ssh-ed25519-cert-v01@openssh.com
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 certificate: ssh-ed25519-cert-v01@openssh.com SHA256:3rfJzCTfq9xb2UYjwCf+FLMo5s46IDcAeKWN4OEN9Qw, serial 0 ID "host:intum:vmschulz30" CA ssh-ed25519 SHA256:xw6Z8D0o6klmmOcnCzhqhTkitvGcjuuQ9JsunW4bvm8 valid forever
debug2: Server host certificate hostname: vmschulz30
debug2: Server host certificate hostname: vmschulz30.in.tum.de
debug3: hostkeys_foreach: reading file "/home/malte/.ssh/known_hosts"
debug3: record_hostkey: found key type ED25519 in file /home/malte/.ssh/known_hosts:1
debug3: load_hostkeys: loaded 1 keys from login.caps.in.tum.de
debug1: No matching CA found. Retry with plain key
debug1: Host 'login.caps.in.tum.de' is known and matches the ED25519 host key.
debug1: Found key in /home/malte/.ssh/known_hosts:1
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: /home/malte/.ssh/id_rsa RSA SHA256:nmOOjBiUCmQEF8b08sB9LIwjSfwxA03cRStE6BrNe2g agent
debug1: Will attempt key: /home/malte/.ssh/id_dsa
debug1: Will attempt key: /home/malte/.ssh/id_ecdsa
debug1: Will attempt key: /home/malte/.ssh/id_ecdsa_sk
debug1: Will attempt key: /home/malte/.ssh/id_ed25519
debug1: Will attempt key: /home/malte/.ssh/id_ed25519_sk
debug1: Will attempt key: /home/malte/.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,ssh-rsa,rsa-sha2-256,rsa-sha2-512,ssh-dss,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521>
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,password
debug3: start over, passed a different list publickey,password
debug3: preferred 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: Offering public key: /home/malte/.ssh/id_rsa RSA SHA256:nmOOjBiUCmQEF8b08sB9LIwjSfwxA03cRStE6BrNe2g agent
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,password
debug1: Trying private key: /home/malte/.ssh/id_dsa
debug3: no such identity: /home/malte/.ssh/id_dsa: No such file or directory
debug1: Trying private key: /home/malte/.ssh/id_ecdsa
debug3: no such identity: /home/malte/.ssh/id_ecdsa: No such file or directory
debug1: Trying private key: /home/malte/.ssh/id_ecdsa_sk
debug3: no such identity: /home/malte/.ssh/id_ecdsa_sk: No such file or directory
debug1: Trying private key: /home/malte/.ssh/id_ed25519
debug3: no such identity: /home/malte/.ssh/id_ed25519: No such file or directory
debug1: Trying private key: /home/malte/.ssh/id_ed25519_sk
debug3: no such identity: /home/malte/.ssh/id_ed25519_sk: No such file or directory
debug1: Trying private key: /home/malte/.ssh/id_xmss
debug3: no such identity: /home/malte/.ssh/id_xmss: No such file or directory
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
login@address.net's password:
debug3: send packet: type 50
debug2: we sent a password packet, wait for reply
debug3: receive packet: type 52
debug1: Authentication succeeded (password).
Authenticated to address.net ([*.*.*.*]:22).
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 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
debug3: Ignored env SESSION_MANAGER
debug3: Ignored env QT_ACCESSIBILITY
debug3: Ignored env COLORTERM
debug3: Ignored env XDG_CONFIG_DIRS
debug3: Ignored env XDG_MENU_PREFIX
debug3: Ignored env GNOME_DESKTOP_SESSION_ID
debug3: Ignored env GTK_IM_MODULE
debug3: Ignored env QT4_IM_MODULE
debug1: Sending env LC_ADDRESS = de_DE.UTF-8
debug2: channel 0: request env confirm 0
debug3: send packet: type 98
debug3: Ignored env GNOME_SHELL_SESSION_MODE
debug1: Sending env LC_NAME = de_DE.UTF-8
debug2: channel 0: request env confirm 0
debug3: send packet: type 98
debug3: Ignored env SSH_AUTH_SOCK
debug3: Ignored env XMODIFIERS
debug3: Ignored env DESKTOP_SESSION
debug1: Sending env LC_MONETARY = de_DE.UTF-8
debug2: channel 0: request env confirm 0
debug3: send packet: type 98
debug3: Ignored env SSH_AGENT_PID
debug3: Ignored env GTK_MODULES
debug3: Ignored env PWD
debug3: Ignored env LOGNAME
debug3: Ignored env XDG_SESSION_DESKTOP
debug3: Ignored env XDG_SESSION_TYPE
debug3: Ignored env GPG_AGENT_INFO
debug3: Ignored env XAUTHORITY
debug3: Ignored env GJS_DEBUG_TOPICS
debug3: Ignored env WINDOWPATH
debug3: Ignored env HOME
debug3: Ignored env USERNAME
debug3: Ignored env IM_CONFIG_PHASE
debug1: Sending env LC_PAPER = de_DE.UTF-8
debug2: channel 0: request env confirm 0
debug3: send packet: type 98
debug1: Sending env LANG = en_US.UTF-8
debug2: channel 0: request env confirm 0
debug3: send packet: type 98
debug3: Ignored env LS_COLORS
debug3: Ignored env XDG_CURRENT_DESKTOP
debug3: Ignored env VTE_VERSION
debug3: Ignored env GNOME_TERMINAL_SCREEN
debug3: Ignored env INVOCATION_ID
debug3: Ignored env MANAGERPID
debug3: Ignored env CLUTTER_IM_MODULE
debug3: Ignored env GJS_DEBUG_OUTPUT
debug3: Ignored env LESSCLOSE
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 LESSOPEN
debug3: Ignored env USER
debug3: Ignored env GNOME_TERMINAL_SERVICE
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
debug3: Ignored env QT_IM_MODULE
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_RUNTIME_DIR
debug1: Sending env LC_TIME = de_DE.UTF-8
debug2: channel 0: request env confirm 0
debug3: send packet: type 98
debug3: Ignored env JOURNAL_STREAM
debug3: Ignored env XDG_DATA_DIRS
debug3: Ignored env PATH
debug3: Ignored env GDMSESSION
debug3: Ignored env DBUS_SESSION_BUS_ADDRESS
debug1: Sending env LC_NUMERIC = de_DE.UTF-8
debug2: channel 0: request env confirm 0
debug3: send packet: type 98
debug3: Ignored env OLDPWD
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
annoyling this happens will all servers I try to connect to and also affects git (over ssh)
thanks in advance for any hints as to what the issue could be <3
回答1:
The symptom suggests that after the reinstall there's a different ssh config; check /etc/ssh/ssh_config for AddressFamily set to any; you could set to inet there or privately in ~/.ssh/config
来源：https://stackoverflow.com/questions/62106072/ssh-times-out-while-connecting-via-ipv6-but-works-with-ipv4