[SOLVED] sshd is on my notebook k51ae ubuntu 10.04; why?; can somebody log in?

floppy_stuttgart · 06-01-2013, 05:16 AM

Hello,
I see a process with htop "/usr/sbin/sshd -D".
Does it mean somebody can log in my pc with ssh?
Or am I wrong and for what is that process?

druuna · 06-01-2013, 05:32 AM

Quote:

Originally Posted by floppy_stuttgart

I see a process with htop "/usr/sbin/sshd -D".

That process points to a listening ssh daemon.

Quote:

Does it mean somebody can log in my pc with ssh?

That depends on how ssh is set up. In theory someone could log in (assuming s/he knows/has the account name and the appropriate password/key).

You might want to have a look at these 2 links:
- SSH Tutorial for Linux
- sshd config

floppy_stuttgart · 06-01-2013, 03:25 PM

the sshd_config is

Quote:

# Package generated configuration file
# See the sshd_config(5) manpage for details

# What ports, IPs and protocols we listen for
Port 22
# Use these options to restrict which interfaces/protocols sshd will bind to
#ListenAddress ::
#ListenAddress 0.0.0.0
Protocol 2
# HostKeys for protocol version 2
HostKey /etc/ssh/ssh_host_rsa_key
HostKey /etc/ssh/ssh_host_dsa_key
#Privilege Separation is turned on for security
UsePrivilegeSeparation yes

# Lifetime and size of ephemeral version 1 server key
KeyRegenerationInterval 3600
ServerKeyBits 768

# Logging
SyslogFacility AUTH
LogLevel INFO

# Authentication:
LoginGraceTime 120
PermitRootLogin yes
StrictModes yes

RSAAuthentication yes
PubkeyAuthentication yes
#AuthorizedKeysFile %h/.ssh/authorized_keys

# Don't read the user's ~/.rhosts and ~/.shosts files
IgnoreRhosts yes
# For this to work you will also need host keys in /etc/ssh_known_hosts
RhostsRSAAuthentication no
# similar for protocol version 2
HostbasedAuthentication no
# Uncomment if you don't trust ~/.ssh/known_hosts for RhostsRSAAuthentication
#IgnoreUserKnownHosts yes

# To enable empty passwords, change to yes (NOT RECOMMENDED)
PermitEmptyPasswords no

# Change to yes to enable challenge-response passwords (beware issues with
# some PAM modules and threads)
ChallengeResponseAuthentication no

# Change to no to disable tunnelled clear text passwords
#PasswordAuthentication yes

# Kerberos options
#KerberosAuthentication no
#KerberosGetAFSToken no
#KerberosOrLocalPasswd yes
#KerberosTicketCleanup yes

# GSSAPI options
#GSSAPIAuthentication no
#GSSAPICleanupCredentials yes

X11Forwarding yes
X11DisplayOffset 10
PrintMotd no
PrintLastLog yes
TCPKeepAlive yes
#UseLogin no

#MaxStartups 10:30:60
#Banner /etc/issue.net

# Allow client to pass locale environment variables
AcceptEnv LANG LC_*

Subsystem sftp /usr/lib/openssh/sftp-server

# Set this to 'yes' to enable PAM authentication, account processing,
# and session processing. If this is enabled, PAM authentication will
# be allowed through the ChallengeResponseAuthentication and
# PasswordAuthentication. Depending on your PAM configuration,
# PAM authentication via ChallengeResponseAuthentication may bypass
# the setting of "PermitRootLogin without-password".
# If you just want the PAM account and session checks to run without
# PAM authentication, then enable this but set PasswordAuthentication
# and ChallengeResponseAuthentication to 'no'.
UsePAM yes

So, is somebody listening? if yes, who installed this and how to find it?

unSpawn · 06-01-2013, 03:58 PM

Quote:

Originally Posted by floppy_stuttgart

So, is somebody listening? if yes, who installed this and how to find it?

Not "somebody" but the service itself. It may have been part of a default OS installation.
If you don't use SSH then disable the service. If you don't need SSH to log in from another networked location then uninstall the service.

If you keep it and run SSH then please change bold items:

Code:

# Package generated configuration file
 # See the sshd_config(5) manpage for details

 # What ports, IPs and protocols we listen for
 Port 22
 # Use these options to restrict which interfaces/protocols sshd will bind to
 #ListenAddress ::
 #ListenAddress 0.0.0.0
 Protocol 2
 # HostKeys for protocol version 2
 HostKey /etc/ssh/ssh_host_rsa_key
 HostKey /etc/ssh/ssh_host_dsa_key
 #Privilege Separation is turned on for security
 UsePrivilegeSeparation yes

 # Lifetime and size of ephemeral version 1 server key
 KeyRegenerationInterval 3600
 ServerKeyBits 768

 # Logging
 SyslogFacility AUTH
 LogLevel INFO

 # Authentication:
 LoginGraceTime 120
 PermitRootLogin no
 StrictModes yes

 RSAAuthentication yes
 PubkeyAuthentication yes
 #AuthorizedKeysFile %h/.ssh/authorized_keys

 # Don't read the user's ~/.rhosts and ~/.shosts files
 IgnoreRhosts yes
 # For this to work you will also need host keys in /etc/ssh_known_hosts
 RhostsRSAAuthentication no
 # similar for protocol version 2
 HostbasedAuthentication no
 # Uncomment if you don't trust ~/.ssh/known_hosts for RhostsRSAAuthentication
 #IgnoreUserKnownHosts yes

 # To enable empty passwords, change to yes (NOT RECOMMENDED)
 PermitEmptyPasswords no

 # Change to yes to enable challenge-response passwords (beware issues with
 # some PAM modules and threads)
 ChallengeResponseAuthentication no

 # Change to no to disable tunnelled clear text passwords
 PasswordAuthentication no

 # Kerberos options
 #KerberosAuthentication no
 #KerberosGetAFSToken no
 #KerberosOrLocalPasswd yes
 #KerberosTicketCleanup yes

 # GSSAPI options
 #GSSAPIAuthentication no
 #GSSAPICleanupCredentials yes

 X11Forwarding yes
 X11DisplayOffset 10
 PrintMotd no
 PrintLastLog yes
 TCPKeepAlive yes
 #UseLogin no

 #MaxStartups 10:30:60
 #Banner /etc/issue.net

 # Allow client to pass locale environment variables
 AcceptEnv LANG LC_*

 Subsystem sftp /usr/lib/openssh/sftp-server

 # Set this to 'yes' to enable PAM authentication, account processing,
 # and session processing. If this is enabled, PAM authentication will
 # be allowed through the ChallengeResponseAuthentication and
 # PasswordAuthentication. Depending on your PAM configuration,
 # PAM authentication via ChallengeResponseAuthentication may bypass
 # the setting of "PermitRootLogin without-password".
 # If you just want the PAM account and session checks to run without
 # PAM authentication, then enable this but set PasswordAuthentication
 # and ChallengeResponseAuthentication to 'no'.
 UsePAM yes

and see http://www.linuxquestions.org/questi...tempts-340366/

floppy_stuttgart · 06-01-2013, 04:14 PM

the ssh_config was

Quote:

# This is the ssh client system-wide configuration file. See
# ssh_config(5) for more information. This file provides defaults for
# users, and the values can be changed in per-user configuration files
# or on the command line.

# Configuration data is parsed as follows:
# 1. command line options
# 2. user-specific file
# 3. system-wide file
# Any configuration value is only changed the first time it is set.
# Thus, host-specific definitions should be at the beginning of the
# configuration file, and defaults at the end.

# Site-wide defaults for some commonly used options. For a comprehensive
# list of available options, their meanings and defaults, please see the
# ssh_config(5) man page.

Host *
# ForwardAgent no
# ForwardX11 no
# ForwardX11Trusted yes
# RhostsRSAAuthentication no
# RSAAuthentication yes
# PasswordAuthentication yes
# HostbasedAuthentication no
# GSSAPIAuthentication no
# GSSAPIDelegateCredentials no
# GSSAPIKeyExchange no
# GSSAPITrustDNS no
# BatchMode no
# CheckHostIP yes
# AddressFamily any
# ConnectTimeout 0
# StrictHostKeyChecking ask
# IdentityFile ~/.ssh/identity
# IdentityFile ~/.ssh/id_rsa
# IdentityFile ~/.ssh/id_dsa
# Port 22
# Protocol 2,1
# Cipher 3des
# Ciphers aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc
# MACs hmac-md5,hmac-sha1,umac-64@openssh.com,hmac-ripemd160
# EscapeChar ~
# Tunnel no
# TunnelDevice any:any
# PermitLocalCommand no
# VisualHostKey no
SendEnv LANG LC_*
HashKnownHosts yes
GSSAPIAuthentication yes
GSSAPIDelegateCredentials no

Now, I will desinstall ssh.

widget · 06-01-2013, 06:25 PM

Removing it is probably the best thing for you to do.

It will make you feel better.

Ssh is actually of little threat to your security as set up. Any one attempting to log in to your box would have to know your IP address, and your password, passphrase or key.

However if you never use ssh why have it? That is simply bloat and worth removal in any case.

I use it over our local network to send packages to my wifes box on the rare occasions this is needed.

I can also use it to log in remotely and securely to my Dreaded Mother in Laws box to run update/upgrade cycles for her.

This is the most commonly used use for ssh and is used by maintainers of remove servers a lot. They generally use a key or even a combination of a key and a password.

I install using the Debian netinstall image so I know how it gets the boxes mentioned here. It is a default option but you can remove that from the list during installation so I am the one that installed it.

As Ubuntu is based on Debian and the main difference the lack of many choices I would say that it is Ubuntu that installed this for you. You still could have known what was being installed. There are the release notes that no one reads and there is a file you can download from the main download site that will list all packages that are going to be installed.

While I would love to denigrate Ubuntu here I can tell you that having it set up to a certain point makes it easier to use. It is one of the most asked about features in help sections of their forum.

While it does take physical access to your box I would be more concerned about the fact that when you boot to recovery mode you will be presented, with no password required, a root prompt.

TobiSGD · 06-01-2013, 07:53 PM

If you are worried about the security of your box you should update your OS. Ubuntu 10.04 is not supported anymore and gets no bugfixes and security upgrades.

floppy_stuttgart · 06-08-2013, 03:06 PM

ssh desinstalled. Topic closed.