Linux Networking





The variety of Linux distributions creates myriad issues relating to configuration and operations when computers are networked, not the least of which is the use of various network management applications, some of which are included with specific distributions, while others are standalone applications.

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I installed dietpi today on a Zero w. (did it on a 3B+ and setup as Hotspot no problem). I wanted to setup the zero as a webcam.
I did this 4 times before I started to install or change the configuration and reboot at least 2 times to make sure all was good.
I changed the setup to US. connected to the Wi-Fi.
Updated to the latest version of dietpi. Update the firmware.
Changed drop bear to ssh.
installed REALVNC.
But when I Install RPI WEB CAM it keeps rebooting and I can't stop it.
As I said after the 3rd time I flashed a fresh image again and rebooted at least 2 times after each change or install until I got to the RPI Web CAM issue.
I get "You're in emergency mode. Enter root password for maintenance or CTRL D.
I tried dietpi for the password and root. CTRL D does nothing but reboot back to the same area.
I'm assuming there is am issue with RPI Web Cam.
And Yes I made sure the power supply is good. I replaced the power supply with one used on my Pi3B+. It's 5.2V, 3amps.
I even tested it with my voltmeter. The issue is this pi Zero W setup works fine with a full version of Raspian and the RPI WEB CAM version I had to manually configure. I switched back to that card and all is fine. I just like the small footprint and ease of setup with DietPi. And it only starts to reboot when I add in the Web Cam distro on DietPi. I even tried some other packages after my 4th attempt, on the card, flashed a new image. In fact I added a few distros to the DietPi setup …
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Dear Experts

in the Windows Active Directory domain controller environment joining the windows client to the domain controller by assigning the IP address and preferred DNS pointing to Windows AD server (which functions as domain controller and also name server).
 Joining the windows client does not require manually creating the entries in the forward and reverse zones, the moment windows client device is joined the records are automatically created in the DNS server.   Now how to make Linux servers in the network to use windows AD server as its  DNS server,  should we have to manually create forward zone and reverse zone entries and then configure Linux server to use windows AD server as its DNS server, please suggest .
how to find number of count in the unix logs for a grep search keyword say 'nullpointerexception on deviding 109418 with 0' please advise
Dear Experts

I would like to understand the need for Windows Active Directory services OR openldap in the organisation where there are multiple departments and various access controls on network resources like internet access/CRM/ERP, EMAIL.  Each department will have working on different modules of CRM/ERP/network data store. is it recommended to make all the business applications CRM/ERP/email to authenticate with Windows Active Directory services OR openldap,  the organisation has more than 500 users however with branches and each location minimum of 100 to 125 users using the business applications though the internet or mpls connectivity, please help me understand domain controller setup with windows AD/open ldap real benefits for the company wide. thanks.
Hi All,

I'm having an issue with CentOS and webhosting.

wget -O-  works
wget -O- http://myServerIP/    -> 403 Forbidden.

In IIS I would just add the name to the host header.  
How do I configure this or allow the IP to serve the same path as for the IP?

Thanks in advanced.
I have a Red Hat 7.1 server.  I cannot FTP into the RH7.1 server I get a message 530 Login incorrect.
I can receive files if I use FTP from the RH7.1 server but I cannot SEND files from the RH7.1 server.
When attempting to send files from the RH7.1 server a zero length file is put on the receiving server but no data is ever copied to the receiving server and the FTP process on the RH7.1 server hangs.

This is on an internal network with no outside connections so security is not a concern here.
I also tried sftp with no success.

Any suggestions would be greatly appreciated.

Dan Kaib
what is the meaning of below command

less log123.log | grep -i nullpointerexception

why we use less and then grep on it

Please advise
in vi we can use /nullpointerexception to find that string right.

how to find how many occurrence of that string total and go to say 10th occurence line
please advise
Dear Experts

We are using nextcloud which is on ubuntu 16.04 with php, mysql and apache until now we were using within the local network but now there is a requirement to enable this to external network that is from internet hence would like to procure ssl certificate and install the same,
1.  can you please suggest the good source to purchase the ssl certificates
2. at present users are using this solution  by installing the ssl certificates will it have any impact of not functioning or breaking down the system please suggest.
3. can you please help me how to install the ssl certificate in this server instance
what are the best ways to migrate or move Zimbra 8.6 on RedHat Linux 6.6 to Zimbra 8.8

current usage: authentication is LDAP, cbpolicyD,fail2ban, spamfiltering is in cloud level

it is possible to install a latest version of CentOS. but what is the best choice? CentOS or Ubuntu ?

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I have a NAS server that I recently have lost the ability to access using the IP address. When an attempt to access I receive an Access Denied error. Below is what I have checked and the results.

  • I have verified that account credentials are correct.
  • I have verified that the account permissions are correct to access the share.
  • I am able to ping the device from any other device in the network.
  • I am able to access the SMB share using the Hostname and the FQDN with the same account credentials mention above but not the IP address.
  • I have verified that the IP address is not assigned to any other device on the network.
  • I have verified that the ARP table correctly associates the IP address to the correct MAC address. (However after a packet capture when the device attempts to authenticate with the SMB share it gets a response from a different MAC address which I can not locate anywhere on the network.)
  • I have verified that NTLM is not disabled on the device or in GPO.

I have reached out to the manufacturer (Panzura) and they said after reviewing the packet capture and all the items above they believe that it is a network issue. At this point, I have run out of ideas of what to do next. The manufacturer suggested changing the IP address, however, I would like to reserve that as a last resort.
no one in ubuntu 16.04 can change password. permission deni...
and new user (sudo adduser (not permission to give a password).
Hello Experts,

I have a DELL server that I am going to mirror a couple of hard drives. It needs to become a file server.

My question is, is there a NAS software I could install on it and make it NAS server?

Software like FreeNAS or OpenFile. I will like the software to be free or otherwise, I will use a Linux server like CentOS 7 or Ubuntu.

If that is the case configuring Samba will be enough? Recommendation needed, please.

Thank you!
Hello everyone!. Perhaps somebody could help me. I am trying to configure firewallD (Centos 7) so public network only has access to http and https services but my trusted networks to ssh, webmin, http, https, etc...
Btw I have only 1 interface.

I need to achieve something like this:

-interface: eth0
-allowed services: http, https

-interface: eth0
-allowed services: http, https, ssh
-allowed ports: 10000

Ho can I do it?
What is the process needed to get the AWS KVM and ZEN drivers loaded in a VMWare Ubuntu 18.04 LTS System before we use the AWS migration tool to put in on an AWS Instance ?  I’m specifically needing what and how to preload the drtivers etc.
Dear Experts

We have a network of less than 15 systems with 2 broadband connections from 2 different ISP's.
1. ISP1 in their provided router configured the network of and their provided router ip and function's as DHCP server in the LAN
2.. similarly ISP 2 also configured in their provided router with network of and their provided router ip and this also funcationing as DHCP server in the LAN.2
Both the routers of both ISP's are connected to the same switch at the present I have turned off ISP 2 router to avoid 2 DHCP in the LAN.
3. have linux server working as internal private DNS
As per the experts exchange experts advice I am in process of procuring the router with 2WAN port so that each one of the ISP will be connected to one of the WAN port and will stop DHCP service on the router level and will configure DHCP server in linux server. I would like to divide the network of to 4 subnets, as following
a)  of ip range 1 to 62
b) of ip range 65 to 126
c) of ip range 128 to 190
d) of ip range from 193 to 254

attached DHCP configuration, request to please review the defined 2 subnets statements in the config
Soution design and suggestion for the below please:
in this dhcp server the defined 2 subnets i,e access point-1 to one of the subnet of above a) i,e  of ip range 1 to 62 and access point-2 to another …
i try to mount synology nas drev on ubuntu but in different ip rang
nas has nfs support and permission
i say
sudo mont /mnt/backup/

my ubuntu har
i get connection timeout
amd with smb connection
sudo mount -t  cifs // /mnt/backup user=Administrator
get mount error(115) Operation now in progress
Dear Experts

We are in process of setting up very small IT infra where local dns (private dns server) be done on ubuntu server16.4.4.  We will be hosting web based application server in on-premise and for the internet we have 2 service providers  both are of different,
1.  ISP 1 provided device enabled with the dhcp service for the network and it is ON with the subnet of  this is more stable connection
2. ISP2 also provided device and enabled with DHCP service for the network and they are asking to turn it ON -
purpose of 2 service provider is to have backup when one is down operation can happen with other service provider
As of now I have not yet turned ISP-2 modem/router ON as this will also function as DHCP server and in a network 2 DHCP server cannot be enabled.
Please suggest the best practice
1. Should I have to ask ISP-2 to configure for different subnet like and configure one DHCP server in linux server define 2 subnets here and stop both service providers ISP-1 and ISP-2 modem/router DHCP service but when the clients systems boot which subnet to be released as ISP-1 may be down and but the DHCP server release the IP of subnet ISP-1 , how to switch here to another subnet - NOT sure if this is good way to go with please suggest
2. stop dhcp service of ISP-1 and ISP-2 devices and configure dhcp server in linux but with one subnet only but segment the ip range for ISP-1  router and gateway sections pointing to ISP-1 in dhcp …
Would anyone know if there is an open source firmware like WRT or Tomato that will work in a Netgear FVS318N? I have a number of these and would like to use OpenVPN but am limited by the Netgear firmware among other limitations. It would be great to have the robustness of WRT or Tomato on one of these.
Any thoughts?
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I have run the command Get-SmbConnection in Powershell and I see that one of the Linux fileshares presented is showing dialect 1.5

My question is if I change the smb.conf for that server, adding protocol = SMB2 - will that 'break' the existing file share using SMB1?

Many thanks

how to connect to samba ad via phpldap?
I have a samba 4 active directory in ubuntu and open ldap (slapd) is running. How to connect  open ldap to ad.
i connect to open ldap via phpldapadmin on port 1389.
i can't connect to openldap from webmin,
Failed to create new tree : The password in the LDAP server configuration is encrypted and cannot be used by Webmin
I have samba 4.x.x ad on ubuntu server 16.04.
I want to create 2 way identification.
then when user logon to domain get sms on mobil. is there any open software to this issue. (not google identificatio, this is only for ssh).

I am seeing a lot of collisions and errors on a WAN port (Sophos SG210) which connects to fiber NTU ( Cisco ME 3400E)

This is 100Mb up/down fiber but I am getting around 60Mb download and 3Mb upload. I think the cause of the slow upload speed is because of the packet collisions and errors.

I get around 70Mb/70Mb when I connect my laptop directly to the NTP.

What would be the cause of the problem?

Here is ifconfig on the WAN link on SG210.

eth1   Link encap:Ethernet HWaddr xx:xx:xx:xx:xx:xx
          inet Mask:
          RX packets:373271 errors:0 dropped:0 overruns:0 frame:0
          TX packets:220080 errors:2306 dropped:0 overruns:0 carrier:2306
          collisions:128842 txqueuelen:1000
          RX bytes:527821557 (503.3 Mb) TX bytes:48346583 (46.1 Mb)

 ethtool eth1
Settings for eth1:
        Supported ports: [ TP ]
        Supported link modes: 10baseT/Half 10baseT/Full
                                100baseT/Half 100baseT/Full
        Supported pause frame use: Symmetric
        Supports auto-negotiation: Yes
        Advertised link modes: 10baseT/Half 10baseT/Full
                                100baseT/Half 100baseT/Full
        Advertised pause frame use: Symmetric
        Advertised auto-negotiation: Yes
If you have two accounts in AWS with one linux host in each - what options do you have to copy files (sftp) between the two hosts?
What would be the options? What would be the fastest? The least costly?

Linux Networking





The variety of Linux distributions creates myriad issues relating to configuration and operations when computers are networked, not the least of which is the use of various network management applications, some of which are included with specific distributions, while others are standalone applications.