File Sharing Flashcards by Fraser Morris

Samba got its name from the SMB protocol, what does SMB SMB stand for?

Server Message Block

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Which 3 Daemon services does Samba use?

smbd - Samba Daemon
nmbd - Netbios Daemon
winbind - Manages connections between Linux & Windows

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What are the 5 Samba package names on Debian based distros?

cifs-utils - utilities to manage shares
samba - server function
samba-common - configs and docs
smbclient - client connections
winbind - winbind functions

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What are the 5 Samba package names on Redhat based distros?

cifs-utils - utilities to manage shares
samba - server function
samba-common - configs and docs
samba-client - client connections
samba-winbind - winbind functions

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Where is the samba documentation installed?

/usr/share/doc/samba* or

/usr/share/doc/samba-version

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Where does Samba store the storage/DB files?

/var/lib/samba

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Where does Samba write log messages?

/var/log/samba

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Where is the main samba config file?

/etc/samba/smb.conf

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Samba utility that mounts samba shares

mount.cifs

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Samba utility that can be used to administer a samba server and remote servers

net

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Samba utility that can lookup netbios info

nmblookup

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Samba utility that is used to manage samba user databases

pdbedit

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Samba utility that executes remote procedure call functions

rpcclient

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Samba utility that displays or modifies Samba access control functions

smbcacs

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Samba utility that connects, list shares or provides ftp like access to a share

smbclient

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Samba utility that manages the smbd daemon

smbcontrol

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Samba utility that mounts samba shares - an older tool that has been replaced by mount.cifs

smbmount

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Samba utility that manages the samba smbpasswd or tdbsam database

smbpaswd

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Samba utility that sends files to a samba printer share

smbspool

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Samba utility that displays the status of the samba server connections

smbstatus

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Samba utility that createss samba file sare backups

smbtar

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Samba utility that tests the syntax of the sm.conf file

testparm

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Samba utility that displays winbindd info

wbinfo

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Samba utility that is used to configure Samba as an active directory domain controller

samba-tool

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Samba directive that defines the workgroup name

workgroup

Samba directive that declares a comment describing the samba server

server string

Samba directive that defines a netbios name for the Samba server (typically only required on legacy windows networks)

netbios name

Samba directive that defines a Kerberos realm

realm

Samba directive that defines which interface(s) to provide the Samba service

interfaces

Samba directive that defines systems that are allowed to access the Samba service

hosts allow

Samba directive that defines systems that should be denied access to the Samba services

hosts deny

Samba directive that stops the nmbd daemon from launching

disable netbios

Samba directive that defines which port numbers to listen on

smb ports

Samba directive that defines enables wins support on a netbios network

wins support

Samba directive that defines the Samba log file

log file

Samba directive that defines the logging level

log level

Samba directive that defines the maximum Samba log size

max log size | 0 = no limit

Samba directive that defines the security mode of the server (ads, domain, server,share or user)

security

Samba directive that defines the account database (ldapsam, smbpasswd or tdbsam)

passdb backend

Samba directive that defines if encryption is allowed or required

smb encrypt

Samba file section names are enclosed in square brackets [ ]. Which file section name sets the directives for all shares?

[global]

Samba file section names are enclosed in square brackets [ ]. Which file section name sets the directives for a new share called LPIC-Share?

[LPIC-Share]

Samba file section names are enclosed in square brackets [ ]. Which file section name sets the directives for user home directories?

[homes]

Samba file section names are enclosed in square brackets [ ]. Which file section name sets the directives for a Samba server acting as a domain Controller? (A samba server that is responding to security authentication requests.

[netlogin]

Samba file section names are enclosed in square brackets [ ]. Which file section name sets the directives for printer shares?

[printers]

Samba file section names are enclosed in square brackets [ ]. Which file section name sets the directives for roaming user profiles?

[profiles]

Samba configuration file directive that describes the samba share

comment

Samba configuration file directive that determines if the Samba share is listed as an available share

browseable

Samba configuration file directive that declares a list of authorised users for a share

valid users

Samba configuration file directive that declares a list of unauthorised users for a share

invalid users

Samba configuration file directive that declares the absolute directory for a share

path

Samba configuration file directive that defines whether a password will be required for a share or not.

public | public = no #password required

Samba configuration file directive that allows only guest connections to a share

guest only

Samba configuration file directive that sets a group name for users connecting to a share

group

Samba configuration file directive that defines whether a share is writable or not

writable

Samba configuration file directive that declares a list or users and/or groups that can write to a share

write list

Samba utility that tests thesmb.conf file for errors. You should run this after every edit of smb.conf.

testparm

What does this command do? | pdbedit -L

pdbedit is used to manage backend user databases. The -L option will list the users in the database.

User John has access to a Samba server (192.168.20.10) on his network. How can John check which shares are available on the server?

Use the smbclient command. | smbclient -L //192.168.20.10 -U John

Samba will use DNS, which port does DNS use?

Which port numbers does the Samba Netbios feature use?

137 - 139 137 - Netbios Name service 138 - Netbios datagram service 139 - Netbios session service

Which port does Samba use for end point resolution?

135

Which port is used for SMB over TCP?

445

User John has access to a Samba server (192.168.20.10) on his network. How can John access a shared named public and use ftp like commands while connected to the share?

use smbclient smbclient //192.168.20.10/public -U John

User John has access to a Samba server (192.168.20.10) on his network. How can John access a shared named public as if it were a local directory?

John need to mount the share. Create a mount point : mkdir /mnt/public then mount the share: mount -t cifs -o username=John,noperm //192.168.20.10/public /mnt/public

The SMB protocol has two security levels what are they?

user level security and share level security share level doesn't use usernames, just passwords to access a share - it is now deprecated. user level - users authenticate with a username and a password.

Samba has 5 modes, what are they?

ads - Allows Samba server to join active Directory as a member domain - User names and passwords are authenticated by the domain controller. server - Usernames and passwords handled by remote (possibly Samba) server share - only password used to access share user - username and password handled by this Samba server

How would you setup Samba as an Active Directory member?

1 Install Samba and utilities 2 If domain controller is providing DNS, change resolv.conf 3 Setup NTP 4 Check domain controller name to IP resolution is correct - modify /etc/hosts if required 5 Modify smb,conf as required 6 Join the domain (e.g. net ads join -U Admin-user 7 Change nsswitch.conf to use winbind 8 Start the winbind service

How would you make all printers defined in /etc/cups/printers available via samba? hint: you'll need 6 directives...

``` [printers] comment = All Printers on Server X path = /var/spool/samba browseable = no guest ok = no writable = no printable = yes ```

User John has access to a Samba server (192.168.20.10) on his network which has a printer share "HP-Laserjet" availbale. How can John send his lpic-notes.txt file to the printer?

with the smbclient tool... smbclient //192.168.20.10/HP-Laserjet -U John -c "print lpic-notes.txt"

Name 8 things you can do to troubleshoot Samba

``` 1 run testparm 2 Check the Service is started and running 3 Check share with smbclient -L 4 Check the workgroup setting 5 Do some network diagnostics, ping, traceroute... 6 Review log files increase debug level 7 check smbstatus (if installed) 8 Review user/group settings ```

How can you break the log file into separate files for each client.

using the log file directive in smb.conf: | log file = /var/log/samba/log.%m

How can you increase and decrease the Samba log level on the fly?

Increase: kill SIGUSR1 smbd-PID Decrease kill SIGUSR2 smbd-PID * Where smbd-PID is the process ID of the smbd service.

What are the Samba Log levels high and low settings?

log level = 0 #off log level = 1 #low log level - 10 # highest

Which Samba utility command will display the netbios name for server 192.168.20.10?

nmblookup -A 192.168.20.10

Which Samba utility command will display the netbios name and hostname for server 192.168.20.10?

nmblookup -S 192.168.20.10

Which Samba utility command would you run to check if a user is in the local samba user database?

pdbedit -L or | pdbedit -L -u username

Which Samba utility command would you run to check if a user on a Samba server that is a member of an Active directory?

wbinfo -u (for user info) | wbinfo -g (for group info)

Which NFS Version supports UDP only, is 32 bit and has limited maximum file sizes and performance issues?

NFSv2, released in 1989, should avoid v2 now if possible.

Which NFS Version utilises "weak cache" to change files in memory, uses multiple ports including TCP and uses NVM Network Lock Manager to help prevent issues?

NFSv3, released in 1995, v3 is the version tested on the LPIC exam.

Which NFS Version introduces Kerberos Authentication,, consolidates multi-ports to a single port and features built-in file lcoking, better performance and security?

NFSv4, released in 2000 and refreshed in 2015.

What is RPC?

Remote Procedure Call protocol. It allows programs to be ignorant of network details but still request services from another system.

The filesystem an NFS server offers is called either an...

export or a share

NFS daemon or kernel service that maps user and group ids?

idmapd (alias rpc.idmapd) - based on settings in idmapd.conf - not used in NFSv3 and lower.

NFS daemon or kernel service that starts the NLM protocol service

locks (alias rpc.lockd) - not used in NFSv4

NFS daemon or kernel service that handles NFS client mount requests on te NFS server side

mountd (alias rpc.mountd)

NFS daemon or kernel service that handles user level NFS file access and data streaming

nfsd (alias rpc.nfsd) not used/required in NFSv4

NFS daemon or kernel service that maps RPC services to port - need to be running on both client and server

portmapper (rpcbind)

NFS daemon or kernel service that manages NFS quotas

rquotad (alias rpc.rquotad)

NFS daemon or kernel service that provides NSM (Network Status Monitor and is used with lockd to provide NLM file locking

statd (alias rpc.statd)

Which directory is the NFS documentation typically installed in?

/usr/share/doc/nfs*/

NFS packages for Redhat based distros

nfs-utils nfs-utils-lib rpcbind portmap

NFS Packages for Debian based distros

nfs-kernel-server nfs-common rpcbind portmap

NFS - Main Export file also known as server export table

/etc/exports

NFS - Directory with extra config files (files with .exports extension)

/etc/exports.d/

NFS - mount config file used on NFS clients

/etc/nfsmount.conf

NFS - primary nfs config files (for both Redhat and Debian based distros)

/etc/sysconfig/nfs /etc/default/nfs-kernel-server /etc/default/nfs-common

NFS file that contains current exports and clients using them - maintained by the kernel

/proc/fs/nfs/exports

NFS file that contains current exports and clients using them - not maintained by the kernel

/var/lib/nfs/xtab

NFS file that contains a list of current exports for client systems - on the server only

/var/lib/nfs/etab

NFS file tat contains a list of current exports and the client systems that currently have them mounted

/var/lib/nfs/rmtab

NFS export directive that ensures clients can't write to the share

ro | read-only

NFS export directive that ensures clients can write to a share

rw | read-write

NFS export directive that doesn't check the write cache has been written to disk before reading data

async

NFS export directive that checks the buffer has been written to disk before reading data

sync

NFS export directive that treats ALL users as anonymous

all_squash

NFS export directive that maps client root accounts to unprivileged accounts

root_squash

NFS export directive that allows client root users to access export as root

no_root_squash

NFS export directive that identifies filesystem export by UUID

fsid

NFS export directive that assigns a specified GID to anonymous group clients

anongid

NFS export directive that assigns a specified UID to anonymous user clients

anonuid

NFS export directive that enables subtree checking so permissions are checked on higher level directories

subtree_check

NFS export directive that ensures permission on higher level directories arenot checked

No_subtree_check

NFS utility that manages and displays information concerning shares

exportfs

NFS utility that mounts a NFS export on a NFS client

mount.nfs

NFS utility that displays client per mount stats

mountstats e.g. mountstats /path/to/mounted/nfsshare

NFS utility that displays client per mount IO stats

nfsiostat

NFS utility that displays NFs client and server activity stats

nfsstats

NFS utility that displays rpc service information

rpcinfo

NFS utility that displays NFS server information, can be used remotely

showmount

NFS utility that unmounts an NFS export

umount.nfs

What command would you run to display a list of all registered RPC programs

rpcinfo -p

exportfs command to export all shares

exportfs -a

exportfs command to unexport all shares

exportfs -u

exportfs command to ignore /etc/exports and use the command line

exportfs -i

exportfs command to export share with command line options

exportfs -o

exportfs command to refresh shares in /etc/exports

exportfs -r or exportfs -ra

exportfs command to provide verbose info

exportfs -v

what is this doing? | exportfs 192.168.20.10:/srv/nfsshare1

Exporting the share "nfsshare1" on the server 192.168.20.10

How can you display NFS shares with all the associated options (ro,rw,sync,async etc..)

exportfs -v for localhost or or exportfs -v 192.168.20.10 or cat /var/lib/nfs/etab

What does an nfs mount definition look like in fstab? force use of version 3.

192.168.20.10:/srv/nfsshare1 /mnt/nfsshare1 nfs intr,nfsvers=3,tcp 0 0

What are the two built in methods of security in NFS

user level share options in /etc/exports and | AUTH_SYS or AUTH_UNIX uid and gid file permissions

What 6 things can we do to improve NFSv3 security?

1 Use TCP (UDP is easier to spoof) 2 Limit wildcard use in export definitions 3 Use root_squash 4 consider all_squash 5 Manage access to ports 6 Use TCP wrappers (hosts.allow and hosts.deny)

What can we do to troubleshoot NFS issues?

1 Check /etc/exports 2 Verify Daemons are running 3 Review NFS ports 4 Check server exports (exportfs -v showmount -e) 5 Basic network diagnostics (ping, traceroute...) 6 Review log file (/var/log/messages |grep nfs) 7 check available exports on the server: showmount -e [server] 9 check NFS export option exportfs -v

Which ports are used in FTP passive mode

Ports 20 and 21

Which ports are used in FTP active mode

unknown, these ports a negotiated between the client and server when establishing the connection

Name the 3 ftp servers mentioned on the LPIC exam

vsftpd pure-FTPd proFTPD

There are 2 command linux command line ftp clients, what are they?

ftp - standard basic ftp client | lftp - refined ftp client

vsftpd package name

vsftpd | sudo apt-get install vsftpd

vsftpd document location

/usr/share/doc/vsftpd-version or | /usr/share/doc/vsftpd

vsftpd config file location

/etc/vsftpd.conf or | /etc/vsftpd/vsftpd.conf

vsftpd config directive to allow anonymous users to create directories

anon_mkdir_write_enable | Default - No

vsftpd config directive to permit anonymous users to rename and delete files

anon_other_write_enable | Default - No

vsftpd config directive to specify the directory an anonymous user changes into on login

anon_root | Default - Directory in /etc/passwd for FTP user

vsftpd config directive to allow anonymous users to see and download world readable file

anon_world_readable_only | Default - Yes

vsftpd config directive to allow anonymous users to upload files

anon_upload_enable | Default - No

vsftpd config directive to allow anonymous user access to the FTP server

anonymous_enable | Default - Yes

vsftpd config directive to change ownership of anonymous users uploaded files

chown_uploads Default - No Define username with chown_username

vsftpd config directive to change the owner of all anonymously uploaded files

chown_username | enable with chown_uploads, set username with chown_username

vsftpd config directive to chroot local users

chroot_local_user | Default - No

vsftpd config directive to define a list of users to be placed in chroot

chroot_list_enable | chroot_list_file

vsftpd config directive to set the default ftp account

ftp_username | Default - ftp

vsftpd config directive to run in either standalone mod or via initialisation service

listen | listen_ipv6

vsftpd config directive to allow local users to login via ftp

local_enable | Default - No

vsftpd config directive to log all ftp queries

log_ftp_protocol | Default - No

vsftpd config directive to check a file for a list of valid/invalid users

userlist_enable | userlist_file

vsftpd config directive to allow ftp users access to commands that modify the filesystem

write_enable | Default - No

How would you check if the vsftpd service supports tcp wrappers

Get the full path which fsftpd then check if the binary uses the libwrap library ldd /usr/sbin/vsftpd |grep libwrap

How would you install pure-ftpd in Debian and Redhat?

``` Debian: apt-get install pure-ftpd Redhat check epel repo is enabled yum -enablerep=epel info pure-ftpd yum -enablerep=epel install pure-ftpd ```

pure-ftpd command line option to listen only for ipv4

- 4 | - -ipv4only

pure-ftpd command line option to listen for only ipv6

- 6 | - -ipv6only

pure-ftpd command line option to chroot all users

- A | - -chrooteveryone

pure-ftpd command line option to set the max number of client connections

- c | - -maxclientsnumber

pure-ftpd command line option to set the max number of clients per IP

- C | - -macclientsperip

pure-ftpd command line option to allow anonymous users

- e | - -anonymously

pure-ftpd command line option to disallow anonymous users

- E | - -noanonymous

pure-ftpd command line option to start the service in the background.

- B | - -daemonize

File Sharing Flashcards

Samba, NFS and FTP