ssh connection closes

From: Tom Van Overbeke (tom.van.overbeke@pandora.be)
Date: 04/22/03


From: "Tom Van Overbeke" <tom.van.overbeke@pandora.be>
Date: Tue, 22 Apr 2003 16:49:10 +0200

Hi,

I noticed sth. strange on a system (linux, openssh-server-3.4p1-2):

I sometimes need to try 3 times before i can connect:

the first time after running the ssh hostname command, i don't even get to
enter my password.
if i try immediately after, i can enter my password, but then the connection
is closed
the next time i try, i can succesfully connect.

if i don't let too much time pass after a disconnect, i can immediately
reconnect. however, if i wait a few minutes, the same scenario occurs.

i ran ssh with the -v option, this is what i get:

the first time:

frontend:~>ssh -v -l vanovto 172.16.208.66
OpenSSH_3.4p1, SSH protocols 1.5/2.0, OpenSSL 0x0090602f
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: Applying options for *
debug1: Rhosts Authentication disabled, originating port will not be
trusted.
debug1: ssh_connect: needpriv 0
debug1: Connecting to 172.16.208.66 [172.16.208.66] port 22.
debug1: Connection established.
debug1: identity file /root/.ssh/identity type -1
debug1: identity file /root/.ssh/id_rsa type -1
debug1: identity file /root/.ssh/id_dsa type -1
ssh_exchange_identification: read: Connection reset by peer
debug1: Calling cleanup 0x80674b0(0x0)

the second time:

frontend:~>ssh -v -l vanovto 172.16.208.66
OpenSSH_3.4p1, SSH protocols 1.5/2.0, OpenSSL 0x0090602f
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: Applying options for *
debug1: Rhosts Authentication disabled, originating port will not be
trusted.
debug1: ssh_connect: needpriv 0
debug1: Connecting to 172.16.208.66 [172.16.208.66] port 22.
debug1: Connection established.
debug1: identity file /root/.ssh/identity type -1
debug1: identity file /root/.ssh/id_rsa type -1
debug1: identity file /root/.ssh/id_dsa type -1
debug1: Remote protocol version 1.99, remote software version OpenSSH_3.4p1
debug1: match: OpenSSH_3.4p1 pat OpenSSH*
Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_3.4p1
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug1: kex: server->client aes128-cbc hmac-md5 none
debug1: kex: client->server aes128-cbc hmac-md5 none
debug1: SSH2_MSG_KEX_DH_GEX_REQUEST sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_GROUP
debug1: dh_gen_key: priv key bits set: 124/256
debug1: bits set: 1570/3191
debug1: SSH2_MSG_KEX_DH_GEX_INIT sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_REPLY
debug1: Host '172.16.208.66' is known and matches the RSA host key.
debug1: Found key in /root/.ssh/known_hosts:18
debug1: bits set: 1598/3191
debug1: ssh_rsa_verify: signature correct
debug1: kex_derive_keys
debug1: newkeys: mode 1
debug1: SSH2_MSG_NEWKEYS sent
debug1: waiting for SSH2_MSG_NEWKEYS
debug1: newkeys: mode 0
debug1: SSH2_MSG_NEWKEYS received
debug1: done: ssh_kex2.
debug1: send SSH2_MSG_SERVICE_REQUEST
debug1: service_accept: ssh-userauth
debug1: got SSH2_MSG_SERVICE_ACCEPT
debug1: authentications that can continue:
publickey,password,keyboard-interactive
debug1: next auth method to try is publickey
debug1: try privkey: /root/.ssh/identity
debug1: try privkey: /root/.ssh/id_rsa
debug1: try privkey: /root/.ssh/id_dsa
debug1: next auth method to try is keyboard-interactive
debug1: authentications that can continue:
publickey,password,keyboard-interactive
debug1: next auth method to try is password
vanovto@172.16.208.66's password:
debug1: ssh-userauth2 successful: method password
debug1: channel 0: new [client-session]
debug1: send channel open 0
debug1: Entering interactive session.
debug1: ssh_session2_setup: id 0
debug1: channel request 0: pty-req
debug1: Requesting X11 forwarding with authentication spoofing.
debug1: channel request 0: x11-req
debug1: channel request 0: shell
debug1: fd 3 setting TCP_NODELAY
debug1: channel 0: open confirm rwindow 0 rmax 32768
debug1: channel_free: channel 0: client-session, nchannels 1
Read from remote host 172.16.208.66: Connection reset by peer
Connection to 172.16.208.66 closed.
debug1: Transferred: stdin 0, stdout 0, stderr 100 bytes in 0.0 seconds
debug1: Bytes per second: stdin 0.0, stdout 0.0, stderr 10175.0
debug1: Exit status -1

and finally the third time (when it works) :

frontend:~>ssh -v -l vanovto 172.16.208.66
OpenSSH_3.4p1, SSH protocols 1.5/2.0, OpenSSL 0x0090602f
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: Applying options for *
debug1: Rhosts Authentication disabled, originating port will not be
trusted.
debug1: ssh_connect: needpriv 0
debug1: Connecting to 172.16.208.66 [172.16.208.66] port 22.
debug1: Connection established.
debug1: identity file /root/.ssh/identity type -1
debug1: identity file /root/.ssh/id_rsa type -1
debug1: identity file /root/.ssh/id_dsa type -1
debug1: Remote protocol version 1.99, remote software version OpenSSH_3.4p1
debug1: match: OpenSSH_3.4p1 pat OpenSSH*
Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_3.4p1
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug1: kex: server->client aes128-cbc hmac-md5 none
debug1: kex: client->server aes128-cbc hmac-md5 none
debug1: SSH2_MSG_KEX_DH_GEX_REQUEST sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_GROUP
debug1: dh_gen_key: priv key bits set: 143/256
debug1: bits set: 1595/3191
debug1: SSH2_MSG_KEX_DH_GEX_INIT sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_REPLY
debug1: Host '172.16.208.66' is known and matches the RSA host key.
debug1: Found key in /root/.ssh/known_hosts:18
debug1: bits set: 1595/3191
debug1: ssh_rsa_verify: signature correct
debug1: kex_derive_keys
debug1: newkeys: mode 1
debug1: SSH2_MSG_NEWKEYS sent
debug1: waiting for SSH2_MSG_NEWKEYS
debug1: newkeys: mode 0
debug1: SSH2_MSG_NEWKEYS received
debug1: done: ssh_kex2.
debug1: send SSH2_MSG_SERVICE_REQUEST
debug1: service_accept: ssh-userauth
debug1: got SSH2_MSG_SERVICE_ACCEPT
debug1: authentications that can continue:
publickey,password,keyboard-interactive
debug1: next auth method to try is publickey
debug1: try privkey: /root/.ssh/identity
debug1: try privkey: /root/.ssh/id_rsa
debug1: try privkey: /root/.ssh/id_dsa
debug1: next auth method to try is keyboard-interactive
debug1: authentications that can continue:
publickey,password,keyboard-interactive
debug1: next auth method to try is password
vanovto@172.16.208.66's password:
debug1: ssh-userauth2 successful: method password
debug1: channel 0: new [client-session]
debug1: send channel open 0
debug1: Entering interactive session.
debug1: ssh_session2_setup: id 0
debug1: channel request 0: pty-req
debug1: Requesting X11 forwarding with authentication spoofing.
debug1: channel request 0: x11-req
debug1: channel request 0: shell
debug1: fd 3 setting TCP_NODELAY
debug1: channel 0: open confirm rwindow 0 rmax 32768
Last login: Tue Apr 22 16:50:17 2003 from 172.21.3.2



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