Aug 5, 2012

Remote log server via HTTP (II)

Let's keep on with the second article about setting up a Remote log server via HTTP. In the preceding part, the NFS daemon was configured in order to be able to export the local log server through NFS, and all this correctly secured by iptables and TCP wrappers. In this article, I am going to continue with the configuration of Samba.

First up, a new user called samba_logs will be adding to the system. From this user, the server machine will be able to hook up to the log directory via Samba. This user will not have neither a personal directory within home nor a shell.

[root@client ~]# useradd -d /dev/null -s /sbin/nologin samba_logs

In turn, this user will also be used to create an ACL (Access Control List) on the /var/log directory, granting read permissions to that user.

[root@client ~]# setfacl -R -m d:u:samba_logs:r /var/log/

[root@client ~]# getfacl /var/log/

Then the samba package will be installed and configured.

[root@client ~]# yum install samba

[root@client ~]# cat /etc/samba/smb.conf
     hosts allow = 192.168.1.
     comment = Log directory
     path = /var/log
     read only = yes
     valid users = samba_logs

Finally, the samba service will be restarted and marked as persistent. Furthermore, the user will be added to the local smbpasswd file.

[root@client ~]# service smb restart

[root@client ~]# chkconfig smb on

[root@client ~]# smbpasswd -a samba_logs

So as to shield the server by iptables, the following rules will be set into the /etc/sysconfig/iptables file (Samba uses the ports 137, 138 and 139 TCP/UDP).

[root@client ~]# cat /etc/sysconfig/iptables
-A RH-Firewall-1-INPUT -s server.local -p tcp --dport 137:139 -j ACCEPT
-A RH-Firewall-1-INPUT -s server.local -p udp --dport 137:139 -j ACCEPT

[root@client ~]# service iptables restart

Remember that is important to keep SELinux and TCP wrappes on. In order SELinux to let read the exported files, it is necessary to activate the variable samba_export_all_ro.

[root@client ~]# getenforce

[root@client ~]# setsebool -P samba_export_all_ro on

And below you can observe the configuration for iptables.

[root@client ~]# cat /etc/sysconfig/iptables
-A RH-Firewall-1-INPUT -s server.local -p tcp --dport 137:139 -j ACCEPT
-A RH-Firewall-1-INPUT -s server.local -p udp --dport 137:139 -j ACCEPT
-A RH-Firewall-1-INPUT -s server.local -p tcp --dport 445 -j ACCEPT

Now we can try out that everything is properly configured by running the next command on server.

[root@server ~]# yum install samba-client cifs-utils

[root@server ~]# smbclient -U samba_logs -L client.local
Enter samba_logs's password: 
Domain=[MYGROUP] OS=[Unix] Server=[Samba 3.5.10-125.el6]

    Sharename       Type      Comment
    ---------       ----      -------
    logs            Disk      Log directory
    IPC$            IPC       IPC Service (Samba Server Version 3.5.10-125.el6)
    samba_logs      Disk      Home Directories
Domain=[MYGROUP] OS=[Unix] Server=[Samba 3.5.10-125.el6]

    Server               Comment
    ---------            -------

    Workgroup            Master
    ---------            -------

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