Ubuntu Servers :: Use Ipv4 Forwarding To Access LAN Network From The WAN?

Jun 11, 2011

I have an OpenVPN(10.04.2 LTS) server running in bridge (TAP) mode. Its sitting behind a router and then a cable modem. The VPN works perfectly but I have a security concern. In order to allow the VPN clients to connect to the internet, I had to enable IPv4 forwarding on the server. Is this is a security hole? Can a hacker access my servers connection from the internet (without authenticating with OpenVPN) and access my network. Can someone use Ipv4 forwarding to access my LAN network from the WAN

I used this command to enable ipv4 forwarding
echo 1 > /proc/sys/net/ipv4/ip_forward

Without IPv4 forwarding my VPN clients can only access my LAN and router, but they cannot reach my modem or the internet.

[Code]...

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Red Hat :: Disabling IPv4 Packet Forwarding: Net.ipv4.ip_forward = 0 (CentOS 5.5)?

Oct 29, 2010

I'm forging a gateway server, We have 2 Internet connection that goes to a load balancer router, and goes to my centos server and from our server goes to a switch for Internet distribution or routing.

OS-CentOS 5.5
[root@server etc]# uname -srio
Linux 2.6.18-194.el5 i386 GNU/Linux

My eth0 and eth1 has the following configuration and IP

[root@server etc]# cat /etc/sysconfig/network-scripts/ifcfg-eth0
# VIA Technologies, Inc. VT6105/VT6106S [Rhine-III]
DEVICE=eth0
BOOTPROTO=none

[code]....

Disabling IPv4 packet forwarding but i already changed it to 1 at sysctl.conf One of the online forum says i need to configure the named.conf deleted some and run it(named.conf) and successful but still when I run network service I still get the :"Disabling IPv4 packet forwarding: net.ipv4.ip_forward = 0" The network is getting the IP range but it doesnt get any Internet connection.

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Fedora :: Access The Network - Eth0 - IPv4 Failed

Jan 23, 2011

I'm working in windows, and that's why I have been able to access the network. In F14, I was able to access the router address while the internet access ain't. Tried restarting network, and still the problem persists. Tried [URL] and the only thing that i've infered is that IPv4 Failed: FATAL plus, the routing table showed 0.0.0.0 as one of the entries (Gateway). So, i've deleted the wired network configuration from the Network Configuration and checked whether the os would pick it up automatically. It still didn't work.

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General :: Use Ipv6 To Access Website While Only Ipv4 Is Supported In Network?

Feb 6, 2011

I'm using Ubuntu Linux as my operating system.In my network only the ipv4 is suported, and I need to access some website through ipv6. How can I do it, is there a way to tunnel from the ipv4 to ipv6.

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OpenSUSE Network :: Connect To Servers Via Ipv4

Jun 8, 2011

Is there a way to access today the openSUSE servers via IPv4? My ISP does not support ipv6, nor my router, and I can't install software right now in openSUSE, because it wants to access te servers via IPv6.

If would be grat to have the download.opensuse.org ipv4 address.

I really need to install some packages, they are required for my school project.

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Ubuntu Servers :: Bind9 Attempting Ipv6 On Ipv4 Network

Oct 29, 2010

After upgrading from 9.10 to 10.04, a hundred or so of (for example)

Code:
error (network unreachable) resolving '14.42.117.203.in-addr.arpa/PTR/IN': 2001:500:13::c7d4:35#53: 1 Time(s)

messages appear in syslog each day. Each URL has from 2 - 6 attempts at various ipv6 addresses. My question is why is bind9 trying to resolve ipv6 addresses? I have done nothing to enable or disable ipv6 and thought that if not explicitly enabled I would not have to be concerned with it.

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Ubuntu Servers :: X Forwarding - Access Via Ssh A Virtualbox Guest Machine?

Mar 29, 2010

host - ubuntu 9.10 desktop
virtualizer - VirtualBox

What will be the easiest way to ssh connect a VM on VirtualBox, exporting its desktop to host, while it is already running ? I found; Howto Access via ssh a Virtualbox Guest machine.

[Code]...

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OpenSUSE Network :: Port Forwarding & Samba Access For An Apache Lamp Server?

May 23, 2010

How do you configure the firewall to allow external web access (it's a LAMP server) and internal access for samba shares ?

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Ubuntu Servers :: Two Network Cards / Can't Access Internal Network

Feb 25, 2011

I've installed Ubuntu Server 10.10 with two network cards. One for external, and one internal.My problem is that as soon as i activate eth1 (external), i can't access the server from the internal network (eth0)

With these settings i can't reach the internal network from inside.If i disable the gateway on eth1 and enable the gateway on eth0, it works.

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Ubuntu Servers :: Make 10.04 VM Look For An IPv4 Address If It Doesn't Seem To By Default?

Jan 5, 2011

how to make a Ubuntu 10.04 server VM look for an IPv4 address if it doesn't seem to by default?

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Ubuntu Servers :: Modify Apache IPv4 Configuration To IPv6 Config?

Feb 25, 2011

I want to modify apache IPv4 configuration to IPv6 configOn both windows and ubuntu.

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Networking :: IPV4 Syntax - Any Host On Network?

Sep 2, 2009

Can someone explain me ipv4 notation like:
192.168.1.0/255.255.255.0
Does it mean "any host on 192.168.1.x" network?

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OpenSUSE Network :: IPv4 Entry For Localhost Missing In 11.4?

Jun 28, 2011

I had some fun here, with my local Cyrus IMAP daemon. I "updated" the machine to openSuse11.4 (from 11.2) by doing a fresh install. Because some of my involved HW here isn't capable of IPv6, I switched it off using yast2:
Netzwerkgeräte/Netzwerkeinstellungen [my translation: Network devices / Network Settings] Globale Optionen [global options] Removed the mark on "IPv6 aktivieren" [activate IPv6]

Then I had a hard fight with Cyrus IMAPd, mostly caused by user brain damage on my part... But one thing really looks like a problem on the Suse side of the fence: My /etc/hosts missed the "localhost"-entry for IPv4 ! This was the contents:

Code:
# special IPv6 addresses
::1 localhost ipv6-localhost ipv6-loopback
127.0.0.2 godot.site godot

[Code].....

I haven't seen this effect on 11.2 here and I haven't seen it on "my other" machine (running 64 bit version of Suse 11.4). But there I think IPv6 is still activated. I will check this, as soon as I get there.

Should this be reported as a potential bug in 11.4 ? Or is there some way, I could have messed up this. (No I didn't edit /etc/hosts by hand, before I corrected this thing)

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OpenSUSE Network :: Assign IPv4 And IPV6 Static Addresses?

Feb 19, 2010

How do I assign IPv4 and IPv6 static addresses permanently in OpenSUSE 11.2? Currently I am only able to assign either IPv4 or IPv6 static address not both. I cannot find even the interfaces file(/etc/sysconfig/network/interfaces).

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Ubuntu Servers :: Access Files Over The Network Without Using FTP?

Sep 15, 2010

I've setup a webserver with LAMP and wondered if it was possible to edit the files without having to login through FTP, as would be the case if I was editing on an IIS server?

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Ubuntu Servers :: FTP Access Inside Local Network Only?

Jun 8, 2011

I've been researching this all day with no luck thus far. Basically I need to cutoff port 21/ftp access from IP addresses outside of my local network. My local IP range is something like 192.168.0.100 - 192.168.0.150 -- so anything outside of this range would automatically be blocked.

Any IP address outside of this range would be denied as I use SFTP for remote access, etc. from home, etc.

I've researched IP tables, tcp wrappers, etc. but am still unsure which would be best for what is probably a simple fix.

Relevant info: Vsftpd via Ubuntu Server 10.10

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OpenSUSE Network :: Can't Access The Smtp Servers

May 22, 2011

It seems I can't access smpt servers both from kmail and php. Kmail says

Code:

Sending failed:
smtp.gmail.com

The message will stay in the 'outbox' folder until you either fix the problem (e.g. a broken address) or remove the message from the 'outbox' folder.The following transport was used: ... I double checked my settings and they are correct. I can ping smtp.gmail.com. I can send emails using thunderbird on a windows box that is connected to the same network as I am.I also tried turning off the firewall through yast but no joy.

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Ubuntu Servers :: Unable To Configure PostGreSQL For Internal Network Access?

Jan 9, 2010

I have a problem configuring my PostGreSQL server for internal network access.

I want to be able to access my postgre server from 192.168.1.10

It works when I set listen_address to *, but if I input 192.168.1.10, or any other IP address, I always get:

Quote:

WARNING: could not create listen socket for "192.168.1.10"
FATAL: could not create any TCP/IP sockets
postgresql.conf section

[Code]....

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Ubuntu Servers :: Apache Setup For Hostname Access On Local Network

Apr 13, 2011

I have installed Ubuntu on four machines at work and have been blown away. On my machine I have Apache setup for web development and other machines can "see" it using my IP address. I would like to have it so they can access by the name of my computer though. I have no local DNS server so I guess I need to hard code the relationship in each machine? Ideally I'd actually like to be able to use subdomains (which I use locally to avoid annoying .htaccess path problems). i.e. from another machine on the network to go to [URL].

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Debian Configuration :: Network - Access Servers Request Failed

Feb 1, 2010

I recently installed two PC with debian lenny (kernel 2.6.26). One is called serveur-debian1 and the second one serveur-debian2. I have installed gnome,samba, mysql5, apache2, php5, and Virtualbox,bridge-tools on them. On serveur-debian2, i installed an other virtual debian lenny with apache2,mysql5,php5,nagios and centreon on it to view my network. I remember having installed a soft to access nntp on serveur-debian2 in order to test nagios.

Since a few days, i have problem to access to my servers. rom my windows 7 client, i try to ping serveur-debian1. Response is OK but not for all resquets Always from the same computer, i try to ping serveur-debian2. Response is OK but not for all again.

When i launch a ping on serveur-debian1 and serveur debian2 at the same time i have:

ping 1 to 10: serveur-debian1: response OK
serveur-debian2: no response
ping 11to 14: serveur-debian1: no response
serveur-debian2: response OK
ping 15 to 25: serveur-debian1: respone OK
serveur-debian2: @ip serveur-debian1 network unreachable (there's no error, it shows me the ip of serveur-debian1)

If i switch on the debian virtual server on the serveur-debian2, and i ping it at the same time, the response is OK for all resquests. The problem is very strange. I can't have a correct connection and when i launch a request from a software which access the mysql server, the requests failed ...

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Ubuntu Servers :: Can't Sudo When X Forwarding

Jul 13, 2011

I'm trying to set up my mythtv backend on a headless box. The many tutorials out there tell you to run mythtv-setup from a machine with a display by x forwarding through ssh.

Code:

ssh -X username@ipaddress /usr/bin/mythtv-setup

The x forwarding works fine except that the first part of the mythtv-setup requires you to stop the mythtv-backend process which you have to do as root. It brings up a box asking for your password (much like is would if you just typed sudo xxxxxxx in the terminal) but it won't accept the password. Looking in the auth log it seems that it can't authenticate

Code:

Jul 13 11:21:08 server su[21869]: pam_unix(su:auth): authentication failure; logname= uid=1000 euid=0 tty=/dev/pts/1 ruser=administrator rhost= user=root
Jul 13 11:21:10 server su[21869]: pam_authenticate: Authentication failure

[code].....

Now I know that my account (administrator) can have root privileges because I can sudo xxxx to my hearts content via ssh in the terminal, but it seems to not work when it's being requested from a forwarded X window....

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OpenSUSE Network :: Setting Up Custom FTP Servers - Access To The Cstrike Folde Via A Ftp Login

Apr 2, 2010

I dont know were to begin to solve my problem and I have been googling for hours to get a hint without any success. I'm runnning a Counterstrike Server on my virtual openSuse server - I'm exploring so don't justify what I am hosting at the moment

I want to make it possible to gain access to the cstrike folde via a ftp login. But I really have no idea were to start. The server is also a webserver, where I can ass FTP accounts for my apache vhosts via plesk - but I dont think this is the solution of my problem, isn't it?

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Ubuntu Servers :: X11 Forwarding Not Working In 9.10 Server

Jan 6, 2010

Pre-exsisting issue from 9.04 server, and has never worked right for me. When I try to open an X11 forwarded app on a mac using the command "ssh -X myusername@serverIP" Other linux machines have similar issues from terminal. I can login just fine and preform any actions I want that do not require X11 forwarding, like say firefox or a manager. I just get the error "Error: no display specified" when trying to do anything with X11 forwarding. I have almost no Linux experience but from tinkering and my friends tinkering wonder if I have a x authority issue.

At one point I had ubuntu desktop package installed (forwarding still did not work then), did a unclean uninstall of it installed Xubuntu. Xubuntu did nothing but throw fits saying I did not have authority to preform all sorts of actions, many relating to root access. This box is meant to be a headless file, print and web server with the ability to login remotely as a convince for administration. I have given up on having a working GUI of any kind on this box. I really do not want to reinstall because of the amount of data on the main partition. What can I start trying to look into?

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Ubuntu Servers :: Web Server 32-bit - DNS - Domain Forwarding?

May 22, 2010

I have set up 10.04 server, got userdir working (/home/username/public_html) so I can access it with h ttp://myipaddress/~username. What do I need to do to get mydomain.com to point to http://myipaddress/~username?

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Ubuntu Servers :: Port Forwarding To Another Server On The LAN?

Dec 13, 2010

We have a Ubuntu system that is connected to 4 different networks.

Code:
eth0: 192.168.12.9
eth1: 192.168.2.142

[code]....

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Ubuntu Servers :: Mail Forwarding To Gmail?

Jun 13, 2011

I just bought a domain, let's say it's called example.com

I also have a gmail account, let's say it's: my.account@gmail.com

I want all email to master@example.com to forward to my.account@gmail.com, and likewise I want all e-mail from my.account@gmail.com to be from master@example.com, and have the reply-to also be master@example.com.

I guess the most pressing issue here is setting up some proxy to forward all my @example.com emails to my gmail. I've been looking through the forums and reading some tutorials, but none of them seem to do exactly what I'm looking for.

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Ubuntu Servers :: Forwarding Mail With Signature?

Jun 23, 2011

At first I want say that I'm regular Ubuntu user, not system administrator. I have installed mail server using Virtual Users And Domains With Postfix, Courier, MySQL And SquirrelMail (Ubuntu 11.04). And it's work!

But I have a challenge. I need to get incoming mail (from another server), zipping mail-body (as html or text) and all attachments into zip-archive, compile new mail with this new attachment (zip-archive) and (most important!) sign all this email with signature which locale in pem-file and send it to BCC-address from incoming mail. I don't know how do it or which tutorial start to read.

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Ubuntu Servers :: Exim4 Forwarding To Local Host

Jun 9, 2010

I've recently had to rebuild our mail server - after the old one over heated - and I've realised I never backed up the config files for exim... so now tyring to work out how the hell to configure what I had....

The setup isn't the most straight forward, so I'll try and explain what happens...

- all emails @longdomain.com are received by an hosted server on the internet
- they are then forwarded to @shortdomain.com, the IP for which is our internet connection which fowards port 25 traffic to the exim server
- the exim server then spam and virus checks the emails and forwards them to an exchange server (sorry but it works well for us)....

I've installed exim4/spamassassin/clamav successfully, and it's setup to receive emails for the relevant domains and relay from the hosted server on the internet (and some local addresses).

how I then setup exim4 to foward all emails on the relevant domains to the exchange server?

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Security :: Define An IP Range That Allows Full Access Eth0-eth1 Forwarding?

Nov 25, 2010

I'm trying to write an iptables config file, but got stuck.So I want to define an IP range that allows full access eth0-eth1 forwarding, and another that is allowed to access some special ip-s. The first part works, I could make the range has full access:

iptables -A FORWARD -m iprange --src-range 192.168.80.20-192.168.80.40 -j ACCEPT
iptables -A FORWARD -i eth1 -o eth0 -m state --state ESTABLISHED,RELATED -j ACCEPT
iptables -A FORWARD -o eth1 -i eth0 -j ACCEPT
iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE
echo 1 > /proc/sys/net/ipv4/ip_forward

But cant find out, how tom make the second rule. How could I put speicified target ip-s in this? I've tried to make a new chain:

[Code]...

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Networking :: IP Forwarding To Another Network?

Apr 5, 2011

I'm facing a challenge in setting up a simple routing between 2 networks. The situation is as follows.We're using 2 networks, 1 that handles all the office traffic and 1 that is used for storage traffic to the NAS. I'm trying to setup a simple router that will forward requests from the office LAN to the storage one, so people can access the NAS interface on the storage LAN.

So, I have a CentOS 5.5 box, connected to both networks that should handle this job. The office LAN is 172.29.38.0/24 and the storage LAN 10.1.2.0/24. IP adrresses of the linux box are 172.29.38.98 (eth0) and 10.1.2.98 (eth1).First I started by enabling IP-forwarding in the kernel:

Code:

# cat /proc/sys/net/ipv4/ip_forward

Below is a copy of the iptables in use:

Code:

# Firewall configuration written by system-config-securitylevel
# Manual customization of this file is not recommended.
*filter
:INPUT ACCEPT [0:0]

[code]....

It just never seems to get to the machine on the other side. I've verified that I can access both networks from the router and I can ping the router from my client.

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