Networking :: DNS Reverse Lookups Not Working For Private IP Addresses / Fix It?
Jul 13, 2011
We have bind 9.3 running on CentOS 5.2. We are able to do reverse lookups for the public IP's but not able to resolve to the private IP's on our network.
p, li { white-space: pre-wrap; } Laptop connects to a (wired) ethernet port on a DLINK DIR-625 wireless router using dhcp. All works perfectly.
Using the same laptop connecting to the same wireless router, but using the wireless adapter and dhcp instead of wired ethernet, I can ping IP addresses on the LAN and also WAN IP's to/from anywhere on the net. I can perform reverse name resolutions (ip to host name), but not forward lookups (host names to ip addresses). I can use the DNS server obtained from dhcp or specify, by ip address, a DNS server to perform the lookups. This makes no difference.
Web pages (LAN server pages or from the internet) are not accessible by site address name or by ip address specifically.
Fedora 12 running under VirtualBox 3.2.8 w/ Bridged networking Host OS Windows 7
I have 3 IP addresses set up in on my Fedora 12 installation: Directory: /etc/sysconfig/network-scripts/ ifcfg-eth0 -> 192.168.0.170 ifcfg-eth0:0 -> 192.168.0.171 ifcfg-eth0:1 -> 192.168.0.172
Hostname is configured to host associated with 192.168.0.170 in /etc/hosts
When I reboot and execute # ifconfig
eth0 is associated with the 172 address and the other addresses are not active. After I run # service network restart
All of the addresses are active and associated with the correct interfaces. Content of my ifcfg files below:
I work in IT, but networking is my weakest area.I'm getting very slow DNS lookups (60+ seconds with lots of page timeouts)in Firefox and Chromium on my Kubuntu laptop. Windows clients (xp and 7) work fine.
I'm running Ubuntu 11.04 and I'm really new to linux. My problem is that whenever I try to browse a site I notice the website loads very slowly because it takes a long time to do lookups. I installed Ubuntu with an onboard NIC and later switched to a PCI NIC (Dlink DGE-530T). Although I disabled the onboard NIC in the BIOS, it doesn't help. Could this conflict in configuration be a problem? My download rates are fine, its just lookups that take really long ( upto ~ 10 seconds). I know the PCI network card is fine because when I jump to Windows 7, lookups are normal again (~ 300ms). At first I thought about installing the sk98lin drivers for the PCI NIC but I saw a couple of places where people have mentioned that the skge driver that comes along with the kernel is better.
I have tried a system wide as well as Firefox disable of IPv6. Here is my /etc/udev/rules.d/70-persistent-net.rules Code: # PCI device 0x1186:0x4b01 (skge) SUBSYSTEM=="net", ACTION=="add", DRIVERS=="?*", ATTR{address}=="00:24:01:14:eb:39", ATTR{dev_id}=="0x0", ATTR{type}=="1", KERNEL=="eth*", NAME="eth0" # PCI device 0x10de:0x0373 (forcedeth) SUBSYSTEM=="net", ACTION=="add", DRIVERS=="?*", ATTR{address}=="00:1e:8c:3e:19:ed", ATTR{dev_id}=="0x0", ATTR{type}=="1", KERNEL=="eth*", NAME="eth1" The interface I want to use according to the listing above is the one with the MAC - 00:24:01:14:eb:39.
I tried removing one of the entries in the file above and rebooting but it still didn't work. Here is a look at my /etc/network/interfaces Code: auto lo iface lo inet loopback # The primary network interface auto eth0 iface eth0 inet static address 192.168.1.10 gateway 192.168.1.1 netmask 255.255.255.0 network 192.168.1.0 broadcast 192.168.1.255
way to get nginx to perform DNS lookups at regular intervals against hostnames that are defined for upstream servers? It seems nginx only performs a DNS lookup once, the first time it starts, and subsequently does not perform any other DNS lookups. This causes problems when the ip addresses of our upstream servers change.
I posted this same question in the nginx forum; however I also posted it here as it seems that not many of the posts there get answered.
I have an odd issue with postfix 2.5.5 trying to relay email internally to a range of mail servers and it keeps ignoring the transport map [ ] and instead always doing mx lookups.
Essentially the server is only allowing connections from an internal network and only for certain domains that it will relay to other mail servers.
It has no local delivery and yet every time I get email passed to it, it will check the local network DNS server for MX information or with diable_dns_lookups enabled (as below) the A record for the domain, and try to deliver to that instead of the transport map destination.
Here's the main.cf # See /usr/share/postfix/main.cf.dist for a commented, more complete version smtpd_banner = $myhostname ESMTP $mail_name (Debian/GNU) biff = no disable_dns_lookups = yes # appending .domain is the MUA's job.
i am logging on to ssh server from my laptop and i have my private key there but i would like to logon also from my desktop at home so how can i copy the key?
I has used centos for all my servers but today i have problem with my router.
I install and configure my router/gateway as follows code...
at previous configuration (centos 4x) everything work well with those configuration but when i use centos 5.4 all my client cannot browse the Internet, its only work when i put the ISP dns (221.321.32.15)
I have a domain and the settings for it are pointed at my IP address. But when I look up my IP address, it does not show my domain as the hostname. What settings do I have to change to make my IP translate into my domain as the hostname?
After years with Linux and using ssh on a daily basis I have to admit I've never setup public/private key authentication and I've never run passwordless logon to ssh. It's not that I've never tried, I have - I've just never got it working. That to me is an almost alien concept as I am a tinkerer at heart and rarely stop until something is working the way I'd like it to. I get the principle of what's going on but I've always had a mental block about it.
I have a strange problem and I can't seem to find clear information on how to do this . I have 2 loadbalancer set up keepalived NAT mode with 2 interfaces each
I recently just upgraded from humble Linux user to confused Linux admin of my own virtual Linux server. When I issue the ifconfig command I get following output.
Code:
venet0:0 Link encap:UNSPEC HWaddr 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00 inet addr:1.2.3.4 P-t-P:1.2.3.4 Bcast:1.2.3.4 Mask:255.255.255.255 UP BROADCAST POINTOPOINT RUNNING NOARP MTU:1500 Metric:1
The WAN IP of the interface is not really 1.2.3.4 I just changed that IP for security reasons.What I am trying to figure out, is it possible to assign a private IP address to the same interface or can I only have one IP address per interface. I understand I have a mask of /32 so I am not going to be able to subnet the address to create any more addresses, so I assume I am stuck with the WAN IP (public IP) that I have, and just need to deal with it.
The reason I ask this is because I have been reading through several DNS/BIND tutorials/walk-throughs, and a lot of them specify setting up a intranet access with 192.168.1.1 address for the local DNS server, but since I am connecting to the sever via SSH I figure I do not need a private IP address.
I have a linux system which is conencted to a corporate lan and it has internet access to it. But i don think that machine hs any static ip or DNS name. I am able to ssh to that machine within the lan but is it possible to ssh to that machine outside the lan using internet?
I want to be able to SSH into my computer that I can't expose port 22 on. I've tried the ssh -R ... several times, but can't manage to make it work.I have my home computer (want to SSH into), server (can SSH into), and some computer I want to SSH from.Do I need to install the sshd on the machine I want to SSH into? What are the commands I need to enter to forward from my server to my home computer?
I'm running Karmic Koala on my laptop and I'm attempting to connect to my university's secure wireless network. I was directed here by the university's computer help websiteI've followed all the steps, but when I open the wireless network authentication applet and try to browse to my private key, I can't find it. The "chose your private key" window claims to be looking for "DER, PEM, or PKCS#12 private keys (*.der, *.pem, *.p12)," and while my private key file shows up as a .p12 file when I open that location with my file browser, the file doesn't show up when I try and browse to it from the authentication applet. I've attached an image which shows the file in one window, but not in the other f clarification.
I'm currently successfully using the Terminal Server Client to connect to an SBS 2003 server at a remote location. I've been trying to figure out if it's possible to connect to any of the XP machines on the LAN behind it. I currently have to use RWW in IE on a VirtualBox XP machine to do that, and I'd love to be able to get rid of VirtualBox completely.
The server has 2 NICs, one connected to the internet, and the other connected to the LAN. There is only one public IP. The computer I'd most like to connect to has a static, private IP. Anybody done anything like this or have any thoughts on how to get it to work?
My Ubuntu server is now providing routing duties to my network, but I'm having trouble opening ports to my network. I have a DynDNS account, so the IP is always current, but I can't ping even my IP directly.
My network map looks like
Internet > SpeedTouch DSL modem with DHCP > eth1 > Ubuntu > eth0 > LAN
With the modem providing a 192.168.1.xx IP to eth1, I can browse fine. The default gateway is my modem. I switched to the public IP of the modem so I could use iptables for firewall duties, but I was locked out of the internet. No gateway was set when I did that, but eth1 received the public IP of my modem.
We have to connect one PC in private network (campus) with other PC (mostly a modem in our case)in public network. Connection should be peer to peer like and we have to use C coding for establishing connection between this two systems. Is it possible if we use port forwarding or is there any other way?
1. I have at work a regular LAN with many PCs, each with a DNS-registered public IP. Therefore I am able to address each of these PCs by their fully-qualified names and, for instance, initiate ssh sessions to any of these computers just by typing "ssh <name_of_machine>" from a terminal.
2. Within the aforementioned LAN I have just created a private network with some clients, which access the LAN through a router (a D-link DIR-825). We have created this private network for many reasons, but most importantly because we need to guarantee that the hosts in this network will remain networked among them even if the LAN goes down for any reason (which unfortunately happens often). But we still need to have access to the hosts in the private network from the LAN.
3. I am able to define port forwarding rules in the router in order to access certain services on the private network's clients. For example. I am able to access (by ssh) hosts "H1" and "H2" on the private network from a client on the LAN by defining rules for forwarding ports "P1" and "P2" on the router's public IP to TCP port 22 on the private IPs of "H1" and "H2", respectively. Then I would access each of these hosts from the LAN by using:
4. The problem with the port forwarding approach is that it is not easily scalable. For instance, If I wanted to enable ssh access to each host in the private network, I would have to define a port forwarding rule for each machine, and then REMEMBER all these port rules when initiating a ssh session from the LAN in order to point to the right host. And the problem gets worse when considering more services in addition to ssh.
5. The ideal solution would be to be have a means for addressing each host in the private network individually, in much the same way in which I address the hosts in the LAN (which have DNS-registered names). For instance, in order to access hosts H1 and H2 as in the previous example, i would like to be able to just type
I guess I can say that what I need is some kind of combined DNS-ing and routing that allows me to communicate with the hosts in the private network from outside of it in a transparent way.
The question is: what are any possible solutions for accomplishing this? I have searched the web and found stuff about things like VPNs, reverse-proxies and NAT servers, but I really can't understand if any of these could serve to solve my problem (BTW, isn't my router doing some sort of NAT-ing already? could I just add some DNS-ing in some way?)
I run a server that is connected to several other boxes in a private network (192.168.0.0). I have had no problems previously, but upon a reinstall of Debian squeeze I have no connectivity to the private network: a ping of other addresses on that network fail. Ping and connection to outside world is fine. This box is configured similarly to another on this private network which connects successfully. I have quadruple-checked all my basic information. I post my ifconfig below of the malfunctioning device, then the ifconfig for equivalent nic on a box connected succesfully to the private network.
Questions:
1.Could it be a cable problem? (I don't see how since the cables have not been changed I do not believe since my reinstallation).
2. What about the difference in the last lines of eth1 below and eth2 of the successful box. Is it significant that the bad eth1 reads Memory:fc3a0000-fc3c0000
In order to enable some one in the remote host to connect my machine. through the command
Code: ssh 127.0.0.1:<remote port>
However when I try to execute the first ssh command above I got the warnning
Code: Warinning: remote port forwarding failed for listen port <remote port>
The problem always happens when the remote host I have tried to connect is my Fedora 14 machine. I can do that when using an Ubuntu as the remote host.
so i start it with ssh -f -R 4096:localhost:22 me@server.com and it comes up and someone can log in at the remote end. how do i close the tunnel from the initiating end ? netstat doesnt seem to identify my end of the tunnel , unless im looking for the wrong thing!
I am looking at using reverse SSH tunnels to manage servers on client sites. I have played around with reverse tunnelling, and have it working on one server back to my middle man server from which I can SSH across from my own PC. All working fine. When I scale this up to 100+ servers reverse tunnelling in, usernames & passwords become a pain, so I'd prefer to use RSA keys instead. My question, finally you might say, is this, to successfully ssh from my PC to the remote server, do the RSA keys need to be on the middle man server as well, or is it just my PC and the remote server?