Networking :: Dynamic IP Address With PTR Record Versus Fixed IP Address Without?
May 7, 2010
I am running my own Postfix mail server. Some time ago I noticed that most email was rejected because of the server's dynamic IP address. So I got a fixed IP address. However then I noticed that some mails got rejected due to failing the reverse DNS check. So my ISP told me to get a range of IP addresses and they could then create a PTR record for one of those addresses. That is now running but it turns out that the IP address used for the PTR record is a ... dynamic IP address. So Spamhaus PBL rejects my emails again.
I need a small shell based program that prints the mac address of physical ethernet adapter from it's firmware. I need this utility for license generation and appliance activation. I have tried several example but none of them is flawless, The easiest method I have found is to parse the output of "ifconfig" command but it has also some drawbacks.
1. Firstly program should differentiate between physical and virtual adapters. Physical means installed on board(wired or wireless) or installed additionally. Virtual adapters are those created by VPN or created by virtualization apps such as VirtualBox/VMWare etc. I am not interested in virtual ones.
2. In case of more them one physical adapters(wired and wireless), it should print the mac address and description(name & vendor) of both/all adapters.
3. If media is disconnected then also it should be able to read the mac address and description(name, vendor) of card.
4. This one is bit complex. I know that 'ethtool' can show you the universal mac address but it's limited to use only 2 types of drivers and won't work in all cases.
When I install Fedora 10 on a new system, I let it default to DHCP. Later, I change the system to a fixed IP address by running system-config-network, selecting eth0, clicking on "Edit", clicking on "Statically set IP addresses:" and filling in the blanks. Is it possible to accomplish the same thing using commands that could be entered in a script? I assume one of them would be
We have Verizon as our ISP with a dynamic IP address. We published our website but the IP changes frequently. How can we set Network address translator(NAT) so our website can be published regardless of IP changes? We don't have domain name and have no intention for one.
Is there some kind of Ubuntu desktop application that notifies you when your WAN ip address has changed? I don't care about my LAN ip address. I need some kind of popup on the desktop when my ISP assigns the next dynamic WAN ip address.
I have a slackware server running ISC dhcpd and bind, and I want to give a dual boot XP / Ubuntu client a fixed address based on its MAC.
I added a host stanza to my server's dhcpd.conf:
Code:
I restarted bind and dhcpd, restarted the client's networking, and it still requests (and receives) its previously leased address, which is not the fixed address I want it to get. I tried dhclient -r to make the client release the old address, didn't help. On networking restart it still gets offered the old (wrong) address. Could it be that dhcpd somehow hangs on to the old lease even after the client sent a DHCPRELEASE?
How do I tell dhcpd to forget about an old lease, and how do I make dhcpd hand out the fixed address (and only that address) I specified for a given MAC, regardless of what the client requests?
I am new to Linux so thought it would be a good learning exercise to try and setup an FTP server using linux.I have downloaded and installed Ubuntu 10 server edition and installed vsftpd, following instructions found on here I have configured the software and I can connect from an FTP client on my windows PC across the internal LAN.I have a couple of questions if I may:
1) a post on this forum suggests that local users can access the FTP server if the correct line is enabled in vsftpd.conf - I have done this and the fact that I can access it shows this is working I would think, however users added subsequently with the useradd command cannot access the server. Filezilla shows a could not connect to server error.
2) how do I give the server a fixed IPv4 address? It is currently using DHCP
3) I need to be able to put files into users folders for them to access offsite, but I don't want them to see each others filesfolders, can I do this?
Ubuntu LTS 8.04 + DHCP. Works fine except for fixed addresses. I mean all devices which need to get fixed IP according to their MACs don't get them and keep to receive random IPs from the range (almost everytime all machines receive the same IP they got from DHCP for the first time).
I have DDNS configured and working for dynamic addresses, but it's not quite right for static addresses yet. The DHCP server assigns the static address, but it doesn't update the DNS sever with the associated host name. Which means I have to use the IP address when accessing the host instead of the host name. How can I get the DHCP server to update the DNS with the host name associated with the fixed-address?Here is my current dhcpd.conf.
Currently my OS is Ubuntu 9.04 Jaunty Jackalope Desktop OS and my web server is Apache2. I have a public address 60.x.y.z and my pc local address is 10.x.y.z. I have a web app in my Apache2 which currently run in localhost(10.x.y.z).
I would like to enable the web app so that it could be browse from outside. I know there maybe some port forwarding process and some commands involved in order to do that. But I have no idea on the steps to do that.
I am working on implementing a protocol on NS2.34 .I really need help to solve this problem . Actually , I don't now whether the problem is generated by the tcl code or the c++ code when I run the simulation, I get this result :
Code: num_nodes is set 64 INITIALIZE THE LIST xListHead 34 45 channel.cc:sendUp - Calc highestAntennaZ_ and distCST_ highestAntennaZ_ = 1.5, distCST_ = 550.0 SORTING LISTS ...DONE! code....
Version 10.04 LTS. Installed desktop version and network worked but I needed a static IP address and the install configures for a DHCP configured address. I tried changing to static address using the System->Preferences->Network Connections application but was unable to get the system to come up with the network up.
So I manually modified the /etc/network/interfaces and the /etc/resolv.conf files. I restart the system but when I do an ifconfig, I don't see a configured IP address on eth0 (only the loopback address). If I run /sbin/ifup eth0 everything then works fine and ifconfig shows the correct address bound to eth0.
I'm running Ubuntu 10.10 and I'm having problems trying to assign it a static IP address. No matter what I put in the Preferences->Networking area (identifying the interface as Manual)... it still will query DHCP for an address if I run the dhclient command. I'm using to using ubuntu server where I just set the IP in the interfaces config file.
I need to obtain daily dynamic IP address from my router for remote user. In order to get into the router page, I need to login to it with ID and password.
Can I tell the server to do this every time it started up to login to router and extract the ip address and send out via email?
The router can only access through web interface and below is what I copied from browser.
I'd like to implement a dynamic menu which will allow me to specify an IP address and read it into memory. This is what I've got so far (it's fairly basic...)
Code: IPS=`ifconfig -a | grep 'inet addr:' | awk '{print $2}' | tr -d "addr:"` PS3='Select an option and press Enter: ' select i in $IPS do case $i in $i) echo $IPS;; esac done echo $IPS
At the moment it just says "Which IP would you like to use" and then freezes, most success I've had is it showing all the IP's listed in ifconfig and then showing the same menu.
I have a few external IP's assigned to me by my ISP. I have IPcop as my router/firewall. I am wondering how to bind 1 of my external ip's to my internal ip address. So I do not have to port forward, etc. For Example, 77.77.77.77 to 192.168.1.123 and on the server it see's the external IP address.
I have trouble getting a gateway to the internet when setting eth0 with a fixed IP address. The gateway address (192.168.2.1 my modem/router) resets to 0.0.0.0 whenever I apply the changes. DHCP works fine but I need a fixed address for my server.
I have 4 servers that I got at auction and they now have ubuntu running with gnome interface.I installed apache2 and tried to edit the conf file but i am not sure if it is a router issue a dns or the config.I am trying to figure out how to set the server to hold the domain from a dynamic ip address and also how to create some test page to see if i can acess from the internet.
I have purchased some books on the command lines and how ubuntu works, I am understanding it so far, but dont know how to have a directory for the dns request to point to for the sitewhat i want to do with the servers...voipeb server for about 4 websites - one is for a volunteer rescue organization, another for a test auction site and 2 portfolio sitesremote file access- if possiblealso on a side note, is it possible to have a message relay from one cell phone or transmit to the server and have it send sms message to cell phones? - this will be used for the rescue group as well.
In my job I use some ethernet embedded devices. They take an ip address from dhcp server or auto ip. I only know mac address.How can I obtain ip from mac address? In other words I need a rarp packet generator.
I dont know for what reason, since 2 days, I started having this message whenever I try to start httpd.I commented "Listen 443", restarted httpd started correctly. I needed to comment "listen 443" in order to be able to start httpdWhat is strange is when I do
I have a dedicated control computer that can only be accessed with web-browser (with its ip-address). My DHCP-server gives a static ip-address to the control computer (base on its mac-address). Somehow and after some time the control computer looses its ip-address (can't ping to it any more) ... and then I have to reset the control computer to get it to pick up the ip-address ... this is not a good solution since the control computer is not nearby. is there a way to force the control computer to renew its ip-address based on its mac-address
My security software has picked up multiple port scanning detections on my router/network and only the IP addresses are available. Is it possible to find out what the remote mac address is to see if the IP source has been spoofed? I've got a couple of different IP sources which were found scanning my ports.
I don't know if my IP and the remote IP address are on the same network or subnet for that matter which is the reason for my wanting to know what the mac address is to find out if its coming from the same remote machine.
Im an academic (university networks and security lecturer) studying/teaching network and operating system security, and inspired by the work of Hovav Shacham set about testing ASLR on linux. Principley I did this by performing a brute force buffer overflow attack on Fedora 10 and Ubuntu 9. I did this by writting a little concurrent server daemon which accidently on purpose didnt do bounds checking.
I then wrote a client to send it a malicious string brute forcing guessed addresses which caused a return-to-libc to the function usleep with a parameter of 16m causing a delay of 16 seconds as laid out in [URL] Once I hit the delay I new I had found the function and could calculate delta_mmap allowing me to create a standard chained ret-to-libc attack. All of that works fine. However .... To complete my understanding I am trying establish where I can find the standard base address for ubuntu 9 (and other distros) for the following, taken from Shacham:-
Quote:
[code]....
/proc/uid/maps gives me some information but not the base address ldd also gives me the randomised starting address for sections in the user address space but neither gives me the base address. Intrestingly ... when a run ldd with aslr on for over (about) 100 times and checked the start point of libc I determined that the last 3 (least significant) hex digits were always 0's and the fist 4 (most significant) where between 0xB7D7 and 0xB7F9. To me this indicated that bits 22-31 were fixed and bits 12-21 were randomized with bits 11-0 fixed. Although even that doesnt define the boundaries observed correctly.
Note: I am replicating the attack to provide signatures to detect it using IDS, and for teaching purposes. I am NOT a hacker and if needed to could reply from my .ac.uk email address as verification.
I want to pass ip address,port address and some parameters from command line using python script.The ip address and port address for establishing socket connection and remaining parameters to execute different connection.
I want to configure a VPN over the Internet.I installed the 'openvpn' package, generated the key file, transfered it by a secure way to the client, and setted up the configuration file.
So, in that configuration file I input the IP addresses of the tunneled interfaces. Both IPs are static in the tunnel.
Then, I've heard somewhere that I can assign a dynamic configuration IP for the client. I do this registering a range.
Well, when I tried to change static IP to dynamic IP (changing '192.168.0.2' to '192.168.0.0/24') in the configuration file, the OpenVPN didn't work.
Obviously I don't know what I'm doing, and I really, don't believe that simply changing the IP will make it work, but I tried.
I hope I explained my problem as well.
My configuration file:
# OpenVPN Server Configuration File dev tun 0 ifconfig 192.168.0.1 192.168.0.2 cd /etc/openvpn secret key_file
In client I execute the 'openvpn' without the '--daemon' parameter.Then I want that my client uses a IP in a range (192.168.0.0/24, for example), instead of a static IP (192.168.0.2).I also thought to use a DHCP server, but I'm not sure that will work.
