RH253

Red Hat Network Services and Security Administration

Welcome!

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Objectives

Understanding and Managing NFS Server Understanding NFS NFS Server Configuration

Creating Shares NFS Client Configuration

Mounting NFS Shares Understanding and Managing SAMBA Server

Understanding SAMBA Server SAMBA Server Configuration

Creating Shares SAMBA Client Configuration

Accessing SAMBA Shares

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Understanding and Managing NFS Server

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What is NFS?

A Network File System (NFS) allows remote hosts to mount file systems over a network and interact with those file systems as though they are mounted locally. This enables system administrators to consolidate resources onto centralized servers on the network. The Network File System (NFS) is the standard for sharing files on a directory with Linux and Unix computers. It was originally developed by Sun Microsystems in the mid-1980s.

You can create shared NFS directories directly by editing the

/etc/exports/etc/exports configuration file, or you can create them with Red Hat's

NFS Configuration tool.

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NFS:- Benefits and Problems

Benefits:Benefits:-> DFS that allows local access to remote files.-> Uses standard client/server architecture.-> Using NFS the server “export” his data to other clients.-> Provide centralize storage solution.-> Users get their data irrespective of physical location.Problems:Problems:-> Network congestion.-> Heavy disk activity on NFS server.-> Its design assume a trusted environment, not a hostile

environment.-> NFS is based on RPC (Remote Procedural Call) which is easy to

exploit.-> For Security reasons – NFS cannot be used over Internet.

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NFS Services portmapportmap : Map calls made from other machines nfsnfs : Translates NFS requests in requests on the local

system rpc.mountdrpc.mountd : Mounts and Unmounts filessystems

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Server Configuration : Sharing Files Exported files are defined in main configuration file /etc/exports/etc/exports Examples : - vi /etc/exports /data *.example.com(ro,sync) station1.cracker.org(rw,sync) /data 192.168.0.0/255.255.255.0(ro,sync) Then After Exporting Files service portmap start service nfs start chkconfig --level 35 portmap on chkconfig --level 35 nfs on

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Client Configuration : Mounting Shares Mounting can be done by using following methods Mount command [ Temporary ] mount -t nfs 192.168.0.254:/data /mntmount -t nfs 192.168.0.254:/data /mnt /etc/fstab file [ Permanent ] 192.168.0.254:/data 192.168.0.254:/data /mnt nfs defaults 0 0 /mnt nfs defaults 0 0

Mounting NFS share on two directories on same systemFirst mount to /home/data

mount -t nfs x.x.x.x:/data /home/data

Now bind /home/data to /backup

mount --bind /home/data /backup

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NFS Commands showmount -eshowmount -e :shows the available shares exportfs -vexportfs -v :Displays a list of shares files and options on a server exportfs -aexportfs -a :Exports all shares listed in /etc/exports ,or given name exportfs -uexportfs -u :Unexports all shares listed in /etc/exports ,or given

name exportfs -rexportfs -r :Refresh the server’s list after modifying /etc/exports

NFS & TCP Wrappers:

Two services are required for TCP wrappers -

Mountd

portmap

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Understanding and Managing SAMBA Server

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What is SAMBA?

Samba is a software package that comes with RHEL that lets you share file systems and printers on a network with computers that use the Session Message Block (SMB) protocol. SMB is the protocol that is delivered with Windows operating systems for sharing files and printers

You can do four basic things with SambaYou can do four basic things with Samba:

Share a Linux directory tree with Windows and Linux/Unix computers

Share a Windows directory with Linux/Unix computers Share a Linux printer with Windows and Linux/Unix computers Share a Windows printer with Linux/Unix computers

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SAMBA Services smbdsmbd : Main File and Printer Sharing Service nmbdnmbd : Act as WINS Server

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Managing SAMBA Server Samba Server can be configured by two methods

Configuration in /etc/samba/smb.conf/etc/samba/smb.conf File Using Configuration GUI Tool system-config-samba system-config-samba

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SAMBA Server side configuration Step1 : Creating samba shares vi /etc/samba/smb.confvi /etc/samba/smb.conf

[mysharename][mysharename]

comment = My Shares from Station1 comment = My Shares from Station1

path = /mysharepath = /myshare

valid users = marcvalid users = marc

invalid users = rootinvalid users = root

public = nopublic = no

writable = yeswritable = yes

browseable = yesbrowseable = yes

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SAMBA Server side configuration For sharing files other than home directories, label them as samba_share_t.

So if you created a special directory /common, you would need to label the directory with the chcon tool.

chcon -t samba_share_t /common

Step 2: Test configuration testparm Step 3: Adding User to samba share who can access samba share smbpasswd -a marc Step 4: Starting SAMBA service service smb start chkconfig --level 345 smb on Step 5 :Testing SAMBA Shares smbclient -L //station1.example.com

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SAMBA Server side configuration

SELinux Portion (if SELinux is enabled on the system,which will be enabled

in RHCE examination)

Check the SELinux boolean by command:

getsebool -a | grep samba

Permit all the SELinux booleans coming in the output:

setsebool -P samba_enable_home_dirs on

setsebool -P samba_share_nfs on

setsebool -P use_samba_home_dirs on

setsebool -P allow_smbd_anon_write on

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SAMBA Client Configuration Client can access samba shares using following methods smbclient //x.x.x.x/myshare smbclient //x.x.x.x/myshare -U -U usernameusername smbmount //station1/myshare /mnt -o username=marcsmbmount //station1/myshare /mnt -o username=marc

Samba Mounts in /etc/fstab file

//station1/myshare /mnt cifs defaults,username=marc 0 0//station1/myshare /mnt cifs defaults,username=marc 0 0 //station1/myshare /mnt cifs defaults,credentials=/etc/cred.txt 0 0//station1/myshare /mnt cifs defaults,credentials=/etc/cred.txt 0 0

Then Create /etc/cred.txt vi /etc/cred.txtvi /etc/cred.txt username=marcusername=marc password=passwordpassword=password

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Samba Mounts in /etc/fstab file

vi /etc/fstabvi /etc/fstab //station1/myshare /mnt smbfs defaults,username=marc 0 0//station1/myshare /mnt smbfs defaults,username=marc 0 0

Using Credentials FileUsing Credentials File vi /etc/fstabvi /etc/fstab //station1/myshare /mnt smbfs defaults,credentials=/etc/cred.txt 0 0//station1/myshare /mnt smbfs defaults,credentials=/etc/cred.txt 0 0

Then Create /etc/cred.txt vi /etc/cred.txtvi /etc/cred.txt username=marcusername=marc password=passwordpassword=password

?Questions