DNS Linux

Hey All,

Is there a way to present a path or other block device to a USB port on a Linux server then have that port connected to a USB port of another device (ie USB to USB) and have it look like a flash disk?

I can plug a USB flash disk to a router just fine. But if I wanted a device to access a path off of another device int he absence of NFS or CIFS capability, that would be handy.

In other words, anyway to assign storage to a USB port in Linux? It would be akin to something like SAN with a target and source just with USB.

Cheers,
DH

I will be setting up a few raspberry pi's in various locations, and they will be creating reverse nat ssh tunnels to my ssh server.

I need to set up a monitoring server at the server's location to monitor the raspberry pi's through the ssh server. The monitoring agent that will be installed on the raspberry pi's is communicating with the monitoring server on port 4700.

My question is:

Since I am using reverse nat ssh tunnels to connect on the ssh server, I am guessing that port 4700 will not be opened. If this is true, is there a way to also open port 4700 in that tunnel, so the monitoring server can access the remote agent?

Thanks

Hi,

So, I am learning meteor.js and signed up for a (cheap, i.e no support) VPS to host my Meteor app. Everything is running fine but I am trying to understand better how Linux works so here is my question:

I am running CentOS 7 on the VPS but it still uses iptables for its firewall.

I had to enable port 80 to access the web server. However, if I reboot the server, it stops working until I do
Code:

iptables -F

Then everything works. But I am thinking that -F might not be the best thing. I have changed the default SSH port from 22 to something else and that also works but I don't think I ever added it to the iptables rules.

If I do a port scan, the new SSH port is indicated as open as well as port 80 but others are closed as they are supposed to be.

Any idea what is doing on behind the scenes that requires iptables -F for the web access to work properly and if I shouldn't be doing iptables -F (I have it in the rc.local file), what is the right way of doing it?

(BTW, I am computer literate but not that familiar with Linux, which I am trying to learn now.)


Kamal

Hello Guys,

I am an newbie, just started with linux, I have installed centos 6.6 and learning it. But I got stuck in some user controls,

Now In my company I wanted to have an Linux Server and need to do the user authentication and wanted to create domain, But also wanted that my Client OS would be MAC and Windows..

Can anybody Help ??




Please reply here or in my email :- Yerunkar11@gmail.com

Once again thanks Again for reading, really appreciated

Hi all,

I understand that Linux by default will limit its Ephemeral port allocation between 32768 to 61000.

I need to identify the applications running on my box (around 500 of them) which are intentionally using a port which happens to be in Ephemeral port range. Objective is to get a list of those apps and flag it so that the developers get to know of it and change their application port.

When I run netstat -nap to get a list of listen ports, I am unable to figure out if the port in Ephemeral range is actually allocated by OS or one of my apps has done it.


Thanks,
linux_it_is

Hi all

I am trying out this dhcp server setup on opensuse 12.1 but it does not seem to be working.

I have eth0 configured to be 192.168.10.1 in a /24 network.

I want to hand out the rest of the address in the same subnet as dhcp addresses. (So everything from 10.2 to 10.255). The default gw is defined as 192.168.10.1, and routing table looks correct. and I only have eth0.


When I start the dhcp, and connect it to the client machine, I see nothing on the wireshark trace. no DHCP discovery or ack messages. And the client machine just keeps trying boot from the network via the network interface. I know I got the right interface (there were blinky options in the bios that lets you identify the correct interface) and the cable is not a problem. (If the cable were a problem the client boot message would say "media fault ... please check media...") instead.

Here is my dhcpd.conf file. I went through man dhcpd already, and cleaned out everything that I apparently don't need. (The original file was copied from a more complicated setup that had multiple subnets and dhcp relays.)

Code:

###################simplfied 
linux-kzy1:/var/lib/dhcp/db # cat /etc/dhcpd.conf
authoritative;

ddns-update-style none;
ddns-updates off;

#Information about the host
subnet 192.168.10.0 netmask 255.255.255.0 {
  max-lease-time 600;
  default-lease-time 600;
  range 192.168.10.2 192.168.10.255;
}

group esx_gep{
  filename "pxelinux.0";
  next-server 192.168.10.1; 
  host testserver1 {hardware ethernet a0:d3:c1:f7:f2:64;}
}

this is what /var/log/message and /var/log/rc.dhcpd.log says:
Code:

**************var log message
Mar 19 18:42:17 linux-kzy1 dhcpd: For info, please visit https://www.isc.org/software/dhcp/
Mar 19 18:42:17 linux-kzy1 dhcpd: Not searching LDAP since ldap-server, ldap-port and ldap-base-dn were not specified in the config file
Mar 19 18:42:17 linux-kzy1 dhcpd: Wrote 0 group decls to leases file.
Mar 19 18:42:17 linux-kzy1 dhcpd: Wrote 0 deleted host decls to leases file.
Mar 19 18:42:17 linux-kzy1 dhcpd: Wrote 0 new dynamic host decls to leases file.
Mar 19 18:42:17 linux-kzy1 dhcpd: Wrote 0 leases to leases file.
Mar 19 18:42:17 linux-kzy1 dhcpd: Listening on LPF/eth0/84:8f:69:cf:7c:41/192.168.10.0/24
Mar 19 18:42:17 linux-kzy1 dhcpd: Sending on   LPF/eth0/84:8f:69:cf:7c:41/192.168.10.0/24
Mar 19 18:42:17 linux-kzy1 dhcpd: Sending on   Socket/fallback/fallback-net
Mar 19 18:42:17 linux-kzy1 dhcpd[12233]: Starting ISC DHCPv4 4.x Server [chroot]..done
linux-kzy1:/home/test/Documents #


*****************var log rc.dhcpd.log
Mar 19 18:42:17 linux-kzy1 dhcpd: Internet Systems Consortium DHCP Server 4.2.2
Mar 19 18:42:17 linux-kzy1 dhcpd: Copyright 2004-2011 Internet Systems Consortium.
Mar 19 18:42:17 linux-kzy1 dhcpd: All rights reserved.
Mar 19 18:42:17 linux-kzy1 dhcpd: For info, please visit https://www.isc.org/software/dhcp/
Mar 19 18:42:17 linux-kzy1 dhcpd: Not searching LDAP since ldap-server, ldap-port and ldap-base-dn were not specified in the config file
Mar 19 18:42:17 linux-kzy1 dhcpd: Wrote 0 group decls to leases file.
Mar 19 18:42:17 linux-kzy1 dhcpd: Wrote 0 deleted host decls to leases file.
Mar 19 18:42:17 linux-kzy1 dhcpd: Wrote 0 new dynamic host decls to leases file.
Mar 19 18:42:17 linux-kzy1 dhcpd: Wrote 0 leases to leases file.
Mar 19 18:42:17 linux-kzy1 dhcpd: Listening on LPF/eth0/84:8f:69:cf:7c:41/192.168.10.0/24
Mar 19 18:42:17 linux-kzy1 dhcpd: Sending on   LPF/eth0/84:8f:69:cf:7c:41/192.168.10.0/24
Mar 19 18:42:17 linux-kzy1 dhcpd: Sending on   Socket/fallback/fallback-net
Mar 19 18:42:17 linux-kzy1 dhcpd[12233]: Starting ISC DHCPv4 4.x Server [chroot]..done
linux-kzy1:/home/test/Documents #

not very interesting stuff or useful, but I found some other messages that is very interesting:

Code:

**********
#no free lease

linux-kzy1:/home/test/Documents # cat /var/log/messages | grep "free lease"
Mar 19 15:53:59 linux-kzy1 dhcpd: DHCPDISCOVER from a0:d3:c1:f7:f2:64 via eth0: network 192.168.10.0/24: no free leases
Mar 19 15:54:03 linux-kzy1 dhcpd: DHCPDISCOVER from a0:d3:c1:f7:f2:64 via eth0: network 192.168.10.0/24: no free leases
Mar 19 15:54:11 linux-kzy1 dhcpd: DHCPDISCOVER from a0:d3:c1:f7:f2:64 via eth0: network 192.168.10.0/24: no free leases
......
Mar 19 17:01:06 linux-kzy1 dhcpd: DHCPDISCOVER from a0:d3:c1:f7:f2:64 via eth0: network 192.168.10.0/24: no free leases
Mar 19 17:01:38 linux-kzy1 dhcpd: DHCPDISCOVER from a0:d3:c1:f7:f2:64 via eth0: network 192.168.10.0/24: no free leases
linux-kzy1:/home/test/Documents #

Which ties into my first question: dhcp no free lease: I googled a bit, I found a post from a guy on ubuntu who has the same error message and the suggested course of action is to change ownership of the lease file to dhcpd and give it 777 for permission. Which I thought is weird, because the lease file is automatically created by the dhcpd itself, so it really shouldn't be a permission issue shouldn't it? (Anyway, tried that didn't do a thing.) right now it is owned by root/root and has this permission: -rw-r--r--.

2nd question: once the client gets a reply from my dhcp server saying no free lease, does it remember this dhcp server as no free lease and does it persist throughout reboots? Because I tried rebooting the client a number of times and I don't see anything on the wireshark at all. You will notice the time stamp on the last "no free lease" message is not as late as the other messages from the var/log/messages or rc.dhcpd.log and I rebooted the client and the dhcp plenty of times since 17:01:38.



Thanks for all your help in advance everyone.

Ok I'm really new at this . Not the old DOS I'm used to. I'm trying to setup my home server using Ubuntu 12.0.4, I've had no success. I have an actual raid sever I'm using. Loaded first HD with Ubuntu 12.0.4, now trying to setup so I can access from anywhere. Remember I'm a newbie so try and keep it simple until I learn Linux. I have my router setup for port forward using 192.168.100 port 21. everything I looked at so far is pretty complicated for a new user. Any help would be great.

I am new to Linux. i am sql DBA, but i need to interact with SAP HANA Database which is on Linux. currently, only way, i can log n to server is through Putty. which opens up cmd interface. is there way, i can log on to Linux server and see drives, files like windows.

thanks,
Sukhi

Hello,

I am new to Linux images (pxe, livecd). I would like to add files to a linux image, like something under etc or var, and have the files be available on the client.
The server I am working on was already configured with a pxe image, and only 2 files are present under the pxe client folder: initrd and vmlinuz. So I am wondering if either of these files contain the dirs /etc, /var, etc..., and how I could add files to them.

To give some background, I have done the same thing in Windows. An image in Windows is typically either boot.img or install.img. You can mount either of these to a folder using the Windows SDK tool imagex.exe /mountrw <img file> 1 <mount point>. From here you can add/remove/modify any files you want. Then commit the changes with imagex.exe /unmount <mountpoint> /commit.

Can someone provide insight to the linux image creation process, which of the files (initrd, vmlinuz/vmlinux, etc...) contain what for the client boot, or something similar to the Windows Image editing process?

I know I'm asking for a range of info, but pointers to any material to help my understanding will be greatly appreciated.

Thanks,
Jon

Hello All,

I am trying to check a tcp/udp port from one server to another server using netcat and nc commands. As there is no manual entry in the system I am not able to check it.

Please let me know any commands are available for checking the port from one server to another server