Weblog entry #56 for Utumno

SSH logins slow
Posted by Utumno on Wed 12 Aug 2009 at 08:23
Tags: none.

Dear lazyweb,

I've got a server ( actually CentOS 5 w/ SSH 4.3 ).
The problem with it is that whenever I try to log in ( using a password ) the login is very slow, takes about 10 seconds.

More precisely,

utumno:/home/leszek# ssh -vvv 192.168.65.14
OpenSSH_5.1p1 Debian-7, OpenSSL 0.9.8k 25 Mar 2009
debug1: Reading configuration data /home/root/.ssh/config
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: Applying options for *
debug2: ssh_connect: needpriv 0
debug1: Connecting to 192.168.65.14 [192.168.65.14] port 22.
debug1: Connection established.
debug1: permanently_set_uid: 0/0
debug1: identity file /home/root/.ssh/identity type -1
debug1: identity file /home/root/.ssh/id_rsa type -1
debug1: identity file /home/root/.ssh/id_dsa type -1
debug1: Remote protocol version 2.0, remote software version OpenSSH_4.3
debug1: match: OpenSSH_4.3 pat OpenSSH_4*
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_5.1p1 Debian-7
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: aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,arcfour128,arcfour256,arcfour,aes192-cbc,aes256-cbc,rijndael-cbc@lysator.liu.se,aes128-ctr,aes192-ctr,aes256-ctr
debug2: kex_parse_kexinit: aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,arcfour128,arcfour256,arcfour,aes192-cbc,aes256-cbc,rijndael-cbc@lysator.liu.se,aes128-ctr,aes192-ctr,aes256-ctr
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,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-sha1,diffie-hellman-group14-sha1,diffie-hellman-group1-sha1
debug2: kex_parse_kexinit: ssh-rsa,ssh-dss
debug2: kex_parse_kexinit: aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,arcfour128,arcfour256,arcfour,aes192-cbc,aes256-cbc,rijndael-cbc@lysator.liu.se,aes128-ctr,aes192-ctr,aes256-ctr
debug2: kex_parse_kexinit: aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,arcfour128,arcfour256,arcfour,aes192-cbc,aes256-cbc,rijndael-cbc@lysator.liu.se,aes128-ctr,aes192-ctr,aes256-ctr
debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,hmac-ripemd160,hmac-ripemd160@openssh.com,hmac-sha1-96,hmac-md5-96
debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,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-md5
debug1: kex: server->client aes128-cbc hmac-md5 none
debug2: mac_setup: found hmac-md5
debug1: kex: client->server aes128-cbc hmac-md5 none
debug1: SSH2_MSG_KEX_DH_GEX_REQUEST(1024<1024<8192) sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_GROUP
debug2: dh_gen_key: priv key bits set: 134/256
debug2: bits set: 530/1024
debug1: SSH2_MSG_KEX_DH_GEX_INIT sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_REPLY
debug3: check_host_in_hostfile: filename /home/root/.ssh/known_hosts
debug3: check_host_in_hostfile: match line 24
debug1: Host '192.168.65.14' is known and matches the RSA host key.
debug1: Found key in /home/root/.ssh/known_hosts:24
debug2: bits set: 513/1024
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: SSH2_MSG_SERVICE_REQUEST sent
debug2: service_accept: ssh-userauth
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug2: key: /home/root/.ssh/identity ((nil))
debug2: key: /home/root/.ssh/id_rsa ((nil))
debug2: key: /home/root/.ssh/id_dsa ((nil))
debug1: Authentications that can continue: publickey,gssapi-with-mic,password
debug3: start over, passed a different list publickey,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: Trying private key: /home/root/.ssh/identity
debug3: no such identity: /home/root/.ssh/identity
debug1: Trying private key: /home/root/.ssh/id_rsa
debug3: no such identity: /home/root/.ssh/id_rsa
debug1: Trying private key: /home/root/.ssh/id_dsa
debug3: no such identity: /home/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
root@192.168.65.14's password: 
debug3: packet_send2: adding 64 (len 56 padlen 8 extra_pad 64)
debug2: we sent a password packet, wait for reply

<---- HERE IT HANGS FOR ABOUT 10 SECONDS

debug1: Authentication succeeded (password).
debug1: channel 0: new [client-session]
debug3: ssh_session2_open: channel_new: 0
debug2: channel 0: send open
debug1: Entering interactive session.
debug2: callback start
debug2: client_session2_setup: id 0
debug2: channel 0: request pty-req confirm 1
debug3: tty_make_modes: ospeed 38400
debug3: tty_make_modes: ispeed 38400
debug1: Sending environment.
debug3: Ignored env ORBIT_SOCKETDIR
debug3: Ignored env SSH_AGENT_PID
debug3: Ignored env SHELL
debug3: Ignored env TERM
debug3: Ignored env XDG_SESSION_COOKIE
debug3: Ignored env GTK_RC_FILES
debug3: Ignored env WINDOWID
debug3: Ignored env GTK_MODULES
debug3: Ignored env USER
debug3: Ignored env LS_COLORS
debug3: Ignored env SSH_AUTH_SOCK
debug3: Ignored env GNOME_KEYRING_SOCKET
debug3: Ignored env USERNAME
debug3: Ignored env SESSION_MANAGER
debug3: Ignored env _JAVA_OPTIONS
debug3: Ignored env MAIL
debug3: Ignored env PATH
debug3: Ignored env DESKTOP_SESSION
debug3: Ignored env GDM_XSERVER_LOCATION
debug3: Ignored env PWD
debug3: Ignored env GNOME_KEYRING_PID
debug1: Sending env LANG = en_US.UTF-8
debug2: channel 0: request env confirm 0
debug3: Ignored env GDM_LANG
debug3: Ignored env PS1
debug3: Ignored env GDMSESSION
debug3: Ignored env HISTCONTROL
debug3: Ignored env SHLVL
debug3: Ignored env HOME
debug3: Ignored env LS_OPTIONS
debug3: Ignored env GNOME_DESKTOP_SESSION_ID
debug3: Ignored env LOGNAME
debug3: Ignored env DBUS_SESSION_BUS_ADDRESS
debug3: Ignored env XDG_DATA_DIRS
debug3: Ignored env LESSOPEN
debug3: Ignored env WINDOWPATH
debug3: Ignored env DISPLAY
debug3: Ignored env LESSCLOSE
debug3: Ignored env COLORTERM
debug3: Ignored env XAUTHORITY
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 131072
debug2: channel_input_confirm: type 99 id 0
debug2: shell request accepted on channel 0
Last login: Wed Aug 12 14:23:42 2009 from 192.168.65.20

Has anyone seen something like that?

 

Comments on this Entry

Posted by ajt (199.230.xx.xx) on Wed 12 Aug 2009 at 09:05
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Is this new or has it always been slow?

Can you run OpenSSH in debug on the server to see what it is doing?

I take it you have tried with SSH-keys on this box and that isn't slow?

--
"It's Not Magic, It's Work"
Adam

[ Parent | Reply to this comment ]

Posted by Anonymous (80.68.xx.xx) on Wed 12 Aug 2009 at 12:06
Is it a DNS issue? Sometimes servers/services want to lookup the IP you're connecting from - and if DNS is slow then things stall.

Could be something to check, anyway.

Steve

[ Parent | Reply to this comment ]

Posted by Anonymous (217.91.xx.xx) on Wed 12 Aug 2009 at 14:16
If you havent already set it:

# echo "UseDNS no" >> /etc/ssh/sshd_config

[ Parent | Reply to this comment ]

Posted by sebg (217.128.xx.xx) on Wed 12 Aug 2009 at 14:43
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client-side, check this value :

GSSAPIAuthentication

(should be no if you don't need it)

[ Parent | Reply to this comment ]

Posted by Anonymous (97.65.xx.xx) on Wed 12 Aug 2009 at 17:01
it's well past that stage that it's failing, though I've seen GSSAPPI be a big cause of slow downs in the past and pretty much turn it off by default.

[ Parent | Reply to this comment ]

Posted by sebg (217.128.xx.xx) on Wed 12 Aug 2009 at 17:13
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do you use MaxStartups ?

[ Parent | Reply to this comment ]

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