SSH connection freezes after successful login (sometimes)

https://stackoverflow.com/questions/19713232

ssh
openssh

02-07-2022
|

Pergunta

I got the following script:

COUNTER=0
while [  $COUNTER -lt 1000 ]; do
    echo The counter is $COUNTER
    let COUNTER=COUNTER+1
    echo -e date\\nexit | sshpass -p 'XXXXXX' ssh -vvv -o ConnectTimeout=30000 -o LogLevel=DEBUG3 -t -t -l root xx.xx.xx.xx

Basically, it executes the "date" command 1000 times on a remote server. Once in a while (1-5 times of these 1000 runs), the ssh freezes after the login and nothing is executed. Nothing I write at the console works, my only option is ctrl+C to kill the session or ctrl+Z to kill the script. Here are the error logs of both successful and frozen session:

Successful:

OpenSSH_5.1p1, OpenSSL 0.9.8j-fips 07 Jan 2009
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: Applying options for *
debug3: cipher ok: aes256-ctr [aes256-ctr,aes128-ctr,aes128-ctr,aes192-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc]
debug3: cipher ok: aes128-ctr [aes256-ctr,aes128-ctr,aes128-ctr,aes192-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc]
debug3: cipher ok: aes128-ctr [aes256-ctr,aes128-ctr,aes128-ctr,aes192-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc]
debug3: cipher ok: aes192-ctr [aes256-ctr,aes128-ctr,aes128-ctr,aes192-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc]
debug3: cipher ok: arcfour256 [aes256-ctr,aes128-ctr,aes128-ctr,aes192-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc]
debug3: cipher ok: arcfour128 [aes256-ctr,aes128-ctr,aes128-ctr,aes192-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc]
debug3: cipher ok: aes128-cbc [aes256-ctr,aes128-ctr,aes128-ctr,aes192-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc]
debug3: cipher ok: 3des-cbc [aes256-ctr,aes128-ctr,aes128-ctr,aes192-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc]
debug3: ciphers ok: [aes256-ctr,aes128-ctr,aes128-ctr,aes192-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc]
debug2: mac_setup: found hmac-sha1
debug3: mac ok: hmac-sha1 [hmac-sha1]
debug3: macs ok: [hmac-sha1]
debug1: Applying options for *
debug2: ssh_connect: needpriv 0
debug1: Connecting to 10.23.66.193 [10.23.66.193] port 22.
debug2: fd 3 setting O_NONBLOCK
debug1: fd 3 clearing O_NONBLOCK
debug1: Connection established.
debug3: timeout: 125163520 ms remain after connect
debug1: permanently_set_uid: 0/0
debug3: Not a RSA1 key file /root/.ssh/id_rsa.
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
debug2: key_type_from_name: unknown key type '-----END'
debug3: key_read: missing keytype
debug1: identity file /root/.ssh/id_rsa type 1
debug1: identity file /root/.ssh/id_dsa type -1
debug1: Remote protocol version 2.0, remote software version OpenSSH_5.3
debug1: match: OpenSSH_5.3 pat OpenSSH*
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_5.1
debug2: fd 3 setting O_NONBLOCK
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug2: kex_parse_kexinit: diffie-hellman-group-exchange-sha256,diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha1,diffie-hellman-group1-sha1
debug2: kex_parse_kexinit: ssh-rsa,ssh-dss
debug2: kex_parse_kexinit: aes256-ctr,aes128-ctr,aes128-ctr,aes192-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc
debug2: kex_parse_kexinit: aes256-ctr,aes128-ctr,aes128-ctr,aes192-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc
debug2: kex_parse_kexinit: hmac-sha1
debug2: kex_parse_kexinit: hmac-sha1
debug2: kex_parse_kexinit: none,zlib@openssh.com,zlib
debug2: kex_parse_kexinit: none,zlib@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: diffie-hellman-group-exchange-sha256,diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha1,diffie-hellman-group1-sha1
debug2: kex_parse_kexinit: ssh-rsa,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-cbc@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-cbc@lysator.liu.se
debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,umac-64@openssh.com,hmac-ripemd160,hmac-ripemd160@openssh.com,hmac-sha1-96,hmac-md5-96
debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,umac-64@openssh.com,hmac-ripemd160,hmac-ripemd160@openssh.com,hmac-sha1-96,hmac-md5-96
debug2: kex_parse_kexinit: none,zlib@openssh.com
debug2: kex_parse_kexinit: none,zlib@openssh.com
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-sha1
debug1: kex: server->client aes256-ctr hmac-sha1 none
debug2: mac_setup: found hmac-sha1
debug1: kex: client->server aes256-ctr hmac-sha1 none
debug1: SSH2_MSG_KEX_DH_GEX_REQUEST(1024<4096<8192) sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_GROUP
debug2: dh_gen_key: priv key bits set: 253/512
debug2: bits set: 2094/4096
debug1: SSH2_MSG_KEX_DH_GEX_INIT sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_REPLY
debug3: check_host_in_hostfile: filename /dev/null
debug3: check_host_in_hostfile: filename /etc/ssh/ssh_known_hosts
Warning: Permanently added '10.23.66.193' (RSA) to the list of known hosts.
debug2: bits set: 2016/4096
debug1: ssh_rsa_verify: signature correct
debug2: kex_derive_keys
debug2: set_newkeys: mode 1
debug2: cipher_init: set keylen (16 -> 32)
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug2: set_newkeys: mode 0
debug2: cipher_init: set keylen (16 -> 32)
debug1: SSH2_MSG_NEWKEYS received
debug1: SSH2_MSG_SERVICE_REQUEST sent
debug2: service_accept: ssh-userauth
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug2: key: /root/.ssh/id_rsa (0x7f95a0842a00)
debug2: key: /root/.ssh/id_dsa ((nil))
debug1: Authentications that can continue: publickey,gssapi-keyex,gssapi-with-mic,password
debug3: start over, passed a different list publickey,gssapi-keyex,gssapi-with-mic,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 public key: /root/.ssh/id_rsa
debug3: send_pubkey_test
debug2: we sent a publickey packet, wait for reply
debug1: Authentications that can continue: publickey,gssapi-keyex,gssapi-with-mic,password
debug1: Trying private key: /root/.ssh/id_dsa
debug3: no such identity: /root/.ssh/id_dsa
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
debug3: packet_send2: adding 64 (len 56 padlen 8 extra_pad 64)
debug2: we sent a password packet, wait for reply
debug1: Authentication succeeded (password).
debug2: fd 6 setting O_NONBLOCK
debug2: fd 7 setting O_NONBLOCK
debug2: fd 8 setting O_NONBLOCK
debug1: channel 0: new [client-session]
debug3: ssh_session2_open: channel_new: 0
debug2: channel 0: send open
debug1: Requesting no-more-sessions@openssh.com
debug1: Entering interactive session.
tcgetattr: Invalid argument
debug2: callback start
debug2: client_session2_setup: id 0
debug2: channel 0: request pty-req confirm 1
debug1: tty_make_modes: no fd or tio
debug1: Sending environment.
debug3: Ignored env LESSKEY
debug3: Ignored env MANPATH
debug3: Ignored env INFODIR
debug3: Ignored env NNTPSERVER
debug3: Ignored env HOSTNAME
debug3: Ignored env XKEYSYMDB
debug3: Ignored env SHELL
debug3: Ignored env TERM
debug3: Ignored env HOST
debug3: Ignored env XDG_SESSION_COOKIE
debug3: Ignored env HISTSIZE
debug3: Ignored env PROFILEREAD
debug3: Ignored env MORE
debug3: Ignored env USER
debug3: Ignored env LS_COLORS
debug3: Ignored env XNLSPATH
debug3: Ignored env ENV
debug3: Ignored env HOSTTYPE
debug3: Ignored env TMOUT
debug3: Ignored env FROM_HEADER
debug3: Ignored env PAGER
debug3: Ignored env CSHEDIT
debug3: Ignored env XDG_CONFIG_DIRS
debug3: Ignored env MINICOM
debug3: Ignored env PATH
debug3: Ignored env MAIL
debug3: Ignored env CPU
debug3: Ignored env PWD
debug3: Ignored env INPUTRC
debug1: Sending env LANG = POSIX
debug2: channel 0: request env confirm 0
debug3: Ignored env PYTHONSTARTUP
debug3: Ignored env HOME
debug3: Ignored env SHLVL
debug3: Ignored env OSTYPE
debug3: Ignored env LESS_ADVANCED_PREPROCESSOR
debug3: Ignored env LS_OPTIONS
debug3: Ignored env LOGNAME
debug3: Ignored env MACHTYPE
debug3: Ignored env LESS
debug1: Sending env LC_CTYPE = en_US.UTF-8
debug2: channel 0: request env confirm 0
debug3: Ignored env XDG_DATA_DIRS
debug3: Ignored env LESSOPEN
debug3: Ignored env INFOPATH
debug3: Ignored env LESSCLOSE
debug3: Ignored env G_BROKEN_FILENAMES
debug3: Ignored env COLORTERM
debug3: Ignored env mc
debug3: Ignored env _
debug2: channel 0: request shell confirm 1
debug2: fd 3 setting TCP_NODELAY
debug2: callback done
debug2: channel 0: open confirm rwindow 0 rmax 32768
debug2: channel_input_confirm: type 99 id 0
debug2: PTY allocation request accepted on channel 0
debug2: channel 0: rcvd adjust 2097152
debug2: channel_input_confirm: type 99 id 0
debug2: shell request accepted on channel 0
debug2: channel 0: read<=0 rfd 6 len 0
debug2: channel 0: read failed
debug2: channel 0: close_read
debug2: channel 0: input open -> drain
debug2: channel 0: ibuf empty
debug2: channel 0: send eof
debug2: channel 0: input drain -> closed
debug1: client_input_channel_req: channel 0 rtype exit-status reply 0
debug2: channel 0: rcvd eof
debug2: channel 0: output open -> drain
debug2: channel 0: rcvd close
debug3: channel 0: will not send data after close
debug3: channel 0: will not send data after close
debug2: channel 0: obuf empty
debug2: channel 0: close_write
debug2: channel 0: output drain -> closed
debug2: channel 0: almost dead
debug2: channel 0: gc: notify user
debug2: channel 0: gc: user detached
debug2: channel 0: send close
debug2: channel 0: is dead
debug2: channel 0: garbage collecting
debug1: channel 0: free: client-session, nchannels 1
debug3: channel 0: status: The following connections are open:
  #0 client-session (t4 r0 i3/0 o3/0 fd -1/-1 cfd -1)

debug3: channel 0: close_fds r -1 w -1 e 8 c -1
debug1: fd 0 clearing O_NONBLOCK
debug1: fd 1 clearing O_NONBLOCK
debug1: fd 2 clearing O_NONBLOCK
Connection to 10.23.66.193 closed.
Transferred: sent 1952, received 3064 bytes, in 0.2 seconds
Bytes per second: sent 8868.1, received 13919.9
debug1: Exit status 0

Frozen:

OpenSSH_5.1p1, OpenSSL 0.9.8j-fips 07 Jan 2009
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: Applying options for *
debug3: cipher ok: aes256-ctr [aes256-ctr,aes128-ctr,aes128-ctr,aes192-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc]
debug3: cipher ok: aes128-ctr [aes256-ctr,aes128-ctr,aes128-ctr,aes192-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc]
debug3: cipher ok: aes128-ctr [aes256-ctr,aes128-ctr,aes128-ctr,aes192-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc]
debug3: cipher ok: aes192-ctr [aes256-ctr,aes128-ctr,aes128-ctr,aes192-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc]
debug3: cipher ok: arcfour256 [aes256-ctr,aes128-ctr,aes128-ctr,aes192-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc]
debug3: cipher ok: arcfour128 [aes256-ctr,aes128-ctr,aes128-ctr,aes192-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc]
debug3: cipher ok: aes128-cbc [aes256-ctr,aes128-ctr,aes128-ctr,aes192-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc]
debug3: cipher ok: 3des-cbc [aes256-ctr,aes128-ctr,aes128-ctr,aes192-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc]
debug3: ciphers ok: [aes256-ctr,aes128-ctr,aes128-ctr,aes192-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc]
debug2: mac_setup: found hmac-sha1
debug3: mac ok: hmac-sha1 [hmac-sha1]
debug3: macs ok: [hmac-sha1]
debug1: Applying options for *
debug2: ssh_connect: needpriv 0
debug1: Connecting to 10.23.66.193 [10.23.66.193] port 22.
debug2: fd 3 setting O_NONBLOCK
debug1: fd 3 clearing O_NONBLOCK
debug1: Connection established.
debug3: timeout: 125163520 ms remain after connect
debug1: permanently_set_uid: 0/0
debug3: Not a RSA1 key file /root/.ssh/id_rsa.
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
debug2: key_type_from_name: unknown key type '-----END'
debug3: key_read: missing keytype
debug1: identity file /root/.ssh/id_rsa type 1
debug1: identity file /root/.ssh/id_dsa type -1
debug1: Remote protocol version 2.0, remote software version OpenSSH_5.3
debug1: match: OpenSSH_5.3 pat OpenSSH*
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_5.1
debug2: fd 3 setting O_NONBLOCK
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug2: kex_parse_kexinit: diffie-hellman-group-exchange-sha256,diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha1,diffie-hellman-group1-sha1
debug2: kex_parse_kexinit: ssh-rsa,ssh-dss
debug2: kex_parse_kexinit: aes256-ctr,aes128-ctr,aes128-ctr,aes192-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc
debug2: kex_parse_kexinit: aes256-ctr,aes128-ctr,aes128-ctr,aes192-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc
debug2: kex_parse_kexinit: hmac-sha1
debug2: kex_parse_kexinit: hmac-sha1
debug2: kex_parse_kexinit: none,zlib@openssh.com,zlib
debug2: kex_parse_kexinit: none,zlib@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: diffie-hellman-group-exchange-sha256,diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha1,diffie-hellman-group1-sha1
debug2: kex_parse_kexinit: ssh-rsa,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-cbc@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-cbc@lysator.liu.se
debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,umac-64@openssh.com,hmac-ripemd160,hmac-ripemd160@openssh.com,hmac-sha1-96,hmac-md5-96
debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,umac-64@openssh.com,hmac-ripemd160,hmac-ripemd160@openssh.com,hmac-sha1-96,hmac-md5-96
debug2: kex_parse_kexinit: none,zlib@openssh.com
debug2: kex_parse_kexinit: none,zlib@openssh.com
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-sha1
debug1: kex: server->client aes256-ctr hmac-sha1 none
debug2: mac_setup: found hmac-sha1
debug1: kex: client->server aes256-ctr hmac-sha1 none
debug1: SSH2_MSG_KEX_DH_GEX_REQUEST(1024<4096<8192) sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_GROUP
debug2: dh_gen_key: priv key bits set: 246/512
debug2: bits set: 2090/4096
debug1: SSH2_MSG_KEX_DH_GEX_INIT sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_REPLY
debug3: check_host_in_hostfile: filename /dev/null
debug3: check_host_in_hostfile: filename /etc/ssh/ssh_known_hosts
Warning: Permanently added '10.23.66.193' (RSA) to the list of known hosts.
debug2: bits set: 2054/4096
debug1: ssh_rsa_verify: signature correct
debug2: kex_derive_keys
debug2: set_newkeys: mode 1
debug2: cipher_init: set keylen (16 -> 32)
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug2: set_newkeys: mode 0
debug2: cipher_init: set keylen (16 -> 32)
debug1: SSH2_MSG_NEWKEYS received
debug1: SSH2_MSG_SERVICE_REQUEST sent
debug2: service_accept: ssh-userauth
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug2: key: /root/.ssh/id_rsa (0x7f774b53da00)
debug2: key: /root/.ssh/id_dsa ((nil))
debug1: Authentications that can continue: publickey,gssapi-keyex,gssapi-with-mic,password
debug3: start over, passed a different list publickey,gssapi-keyex,gssapi-with-mic,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 public key: /root/.ssh/id_rsa
debug3: send_pubkey_test
debug2: we sent a publickey packet, wait for reply
debug1: Authentications that can continue: publickey,gssapi-keyex,gssapi-with-mic,password
debug1: Trying private key: /root/.ssh/id_dsa
debug3: no such identity: /root/.ssh/id_dsa
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
debug3: packet_send2: adding 64 (len 56 padlen 8 extra_pad 64)
debug2: we sent a password packet, wait for reply
debug1: Authentication succeeded (password).
debug2: fd 6 setting O_NONBLOCK
debug2: fd 7 setting O_NONBLOCK
debug2: fd 8 setting O_NONBLOCK
debug1: channel 0: new [client-session]
debug3: ssh_session2_open: channel_new: 0
debug2: channel 0: send open
debug1: Requesting no-more-sessions@openssh.com
debug1: Entering interactive session.
tcgetattr: Invalid argument
debug2: callback start
debug2: client_session2_setup: id 0
debug2: channel 0: request pty-req confirm 1
debug1: tty_make_modes: no fd or tio
debug1: Sending environment.
debug3: Ignored env LESSKEY
debug3: Ignored env MANPATH
debug3: Ignored env INFODIR
debug3: Ignored env NNTPSERVER
debug3: Ignored env HOSTNAME
debug3: Ignored env XKEYSYMDB
debug3: Ignored env SHELL
debug3: Ignored env TERM
debug3: Ignored env HOST
debug3: Ignored env XDG_SESSION_COOKIE
debug3: Ignored env HISTSIZE
debug3: Ignored env PROFILEREAD
debug3: Ignored env MORE
debug3: Ignored env USER
debug3: Ignored env LS_COLORS
debug3: Ignored env XNLSPATH
debug3: Ignored env ENV
debug3: Ignored env HOSTTYPE
debug3: Ignored env TMOUT
debug3: Ignored env FROM_HEADER
debug3: Ignored env PAGER
debug3: Ignored env CSHEDIT
debug3: Ignored env XDG_CONFIG_DIRS
debug3: Ignored env MINICOM
debug3: Ignored env PATH
debug3: Ignored env MAIL
debug3: Ignored env CPU
debug3: Ignored env PWD
debug3: Ignored env INPUTRC
debug1: Sending env LANG = POSIX
debug2: channel 0: request env confirm 0
debug3: Ignored env PYTHONSTARTUP
debug3: Ignored env HOME
debug3: Ignored env SHLVL
debug3: Ignored env OSTYPE
debug3: Ignored env LESS_ADVANCED_PREPROCESSOR
debug3: Ignored env LS_OPTIONS
debug3: Ignored env LOGNAME
debug3: Ignored env MACHTYPE
debug3: Ignored env LESS
debug1: Sending env LC_CTYPE = en_US.UTF-8
debug2: channel 0: request env confirm 0
debug3: Ignored env XDG_DATA_DIRS
debug3: Ignored env LESSOPEN
debug3: Ignored env INFOPATH
debug3: Ignored env LESSCLOSE
debug3: Ignored env G_BROKEN_FILENAMES
debug3: Ignored env COLORTERM
debug3: Ignored env mc
debug3: Ignored env _
debug2: channel 0: request shell confirm 1
debug2: fd 3 setting TCP_NODELAY
debug2: callback done
debug2: channel 0: open confirm rwindow 0 rmax 32768
debug2: channel_input_confirm: type 99 id 0
debug2: PTY allocation request accepted on channel 0
debug2: channel 0: rcvd adjust 2097152
debug2: channel_input_confirm: type 99 id 0
debug2: shell request accepted on channel 0
debug2: channel 0: read<=0 rfd 6 len 0
debug2: channel 0: read failed
debug2: channel 0: close_read
debug2: channel 0: input open -> drain
debug2: channel 0: ibuf empty
debug2: channel 0: send eof
debug2: channel 0: input drain -> closed

The difference is that the frozen log is shorter with a few lines. The first line missing is:

debug1: client_input_channel_req: channel 0 rtype exit-status reply 0

I've tried multiple versions of SSH, but if you wonder about the example I've used version OpenSSH_5.1p1 client and OpenSSH_5.3p1 server.

Any ideas whats wrong or how can I troubleshot the problem are appreciated.

Thanks!

Solução

One possible reason for such behavior would be that you are practically flooding the server with ssh connections, effectively leading to a denial of service, or that you are seeing the consequences of anti-DOS measures set up on the remote server. To rule this out, insert a sleep in your loop.

If you have access to the logs of the ssh server on the remote host, you should find more information. If you don't you can try and start an SSH server on a higher port in debug mode, e.g. /usr/sbin/sshd -D -e -p 1234 (then connect with ssh -p 1234) so you have more precise information .

Licenciado em: CC-BY-SA com atribuição

Não afiliado a StackOverflow