Ubuntu :: Port Forwarding Crutch - Number Of Apps That Are Unable To Have The Outgoing Port Changed ?

Mar 28, 2010

I'm not that great with mailservers, and just been thrown a curveball with a MS Exchange environment for which there is apparently no solution... yeah, right. But is there a workaround?

The problem is that the site mail (SMTP) needs to be sent via port 26 instead of the commonly used 25. Port 25 is mapped to a mailfilter, which apparently causes havoc with some of the mail, and the techs that have been on site trying to coax the Exchange server to co-operate have said that the only way would be to get rid of the filter.

The problem is that there are number of apps that are unable to have the outgoing port changed and so keep sending mail out on port 25.

I look after the Unix/Linux side of things at work, and I was wondering if there was an easy way to set up a Ubuntu box to receive mail on port 25 and just forward it to the MS box on port 26? So, in other words (and I hope this makes sense): monitor port 25, and forward whatever comes in on port 25 to the server on port 26. Simple portforwarding, or is it? What steps do I need to take?

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Networking :: Outgoing Port Forwarding Wrt54gs?

Feb 22, 2010

How would one forward a specific outgoing port to a local computer?

E.G.
Router: 192.168.1.1
Comp 1: 192.168.1.100
Comp 2: 192.168.1.200

When Comp 1 tries to browse to an internet page, forward that connection via the router to comp 2 to display a custom webpage. Using WRT54GS

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Networking :: Shorewall: Port Forwarding Port Is Closed Even After Forwarding?

Dec 12, 2009

I have just set up shorewall on my router running Arch Linux. The external network is on eth0 and the internal network on eth1.I have set it up for masquerading and that works fine and I can open ports to the firewall. But I'm having trouble with port forwarding to my internal machines.The problem I have is that when port 22350 is forwarded to 192.168.1.3 on my local network, checking the port with nmap from a remote computer gives me:

Code:
PORT STATE SERVICE
22350/tcp closed unknown

[code]....

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Ubuntu Security :: SSH Port Forwarding, Disable Or Edit A Forwarded Port?

Nov 1, 2010

sudo ssh -L 750:192.168.123.103:873 username@192.168.123.103It does exactly what it's supposed to do, but how do i edit / remove this rule?Is there some config file where i can alter the forwarding? How does it get stored?Im using Ubuntu 10.10Server Edition (allthough i recon it would be pretty much the same across all versions

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Ubuntu Networking :: Error - Remote Port Forwarding Failed For Listen Port 5500

Aug 7, 2010

When I use the following command:

ssh user@ssh_server -L 5500:localhost:5500 -p 22

everything works fine. I can log in, and local port forwarding is done. Otherwise when I use the command:

ssh user@ssh_server -R 5500:localhost:5500 -p 22

I get an error "remote port forwarding failed for listen port 5500". However when I try remote port forwarding in WinXP by use of putty there is no problem...

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General :: Warning: Remote Port Forwarding Failed For Listen Port 7869

Jul 20, 2010

I tried to make "ssh tunneling", but failed and got this message.

Quote:

Administrator@windstory-PC /
$ ssh -R 7869:localhost:7869 windowsstudy@192.168.0.4
windowsstudy@192.168.0.4's password:

Warning: remote port forwarding failed for listen port 7869 Last login: Wed Jul 21 01:56:04 2010 from 192.168.0.2 -bash-3.2$

1. system environment

192.168.0.2 - windows 7 + copssh
192.168.0.4 - centos 5.4 x86 + openssh

2. Guide for setting "ssh tunneling"

[URL]

3. Added this to sshd.conf

Quote:

AllowTcpForwarding yes

4. "netstat -na|grep 7869" at 192.168.0.4

Quote:

[root:maestro:~]# netstat -na|grep 7869
tcp 0 0 0.0.0.0:7869 0.0.0.0:* LISTEN
tcp 0 0 127.0.0.1:7869 127.0.0.1:53539 ESTABLISHED

[code]....

5. result of "ssh -vvv -R 7869:localhost:7869 windowsstudy@192.168.0.4"

Quote:

debug3: authmethod_lookup password
debug3: remaining preferred: ,password
debug3: authmethod_is_enabled password

[code]....

6. I added 7869 for telnet service as follow;

Quote:

mytelnet 7869/tcp # My Telnet server

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Ubuntu Networking :: Port Forwarding Through A Specific Port?

Jul 14, 2011

I want to set my ip as static and port forward it through a specific port can anyone help me with this im using ubuntu 10 with 64 bit OS

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Security :: Port-bind Shellcodes Work With Port-forwarding?

Apr 27, 2011

I'll explain this in one sentence: Is it possible to program a port-binding shellcode in which people across the Internet can connect to, without being thwarted by the router blocking their data because the port its bound to doesn't allow port-forwarding

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Networking :: Iptables - Port Forwarding To Blocked Port?

Mar 25, 2010

I have a mail server on which I would like to block port 25 on my eth0 for everyone except our external spam filter. the problem is that I want our users to be able to connect via port 10025 which is forwarded to port 25, which then is blocked...

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Networking :: Setup Port Forwarding Of Port 1000 To Ip 192.168.1.200?

Oct 24, 2010

I had to add them to my firewall script when I installed openvpn on my dd-wrt router:

iptables -I FORWARD -i br0 -o tun0 -j ACCEPT
iptables -I FORWARD -i tun0 -o br0 -j ACCEPT
iptables -I INPUT -i tun0 -j REJECT
iptables -t nat -A POSTROUTING -o tun0 -j MASQUERADE

what should I add/change to set up port forwarding of port 1000 to ip 192.168.1.200. also how to get the answer sent by 192.168.1.200 follow the same route used by the data received through port forwarding.

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General :: X11 - Unable To Add Any Port Forwarding Rules To Router

Feb 22, 2011

Say I have Computer A behind a router with NAT. I'm unable to add any port forwarding rules to that router. Then I have Computer B with a public IP address that I want to forward X windows from. This computer is headless, but does have a video card so X windows can be used. Here are some of the things I'd perform to setup my scenario.

1. Computer B, I'd run xhost + public_ip of NAT router.
2. Make sure that computer B's sshd service has X11 forwarding enabled.
3. SSH from Computer A to Computer B with the X windows forward option.
4. Once in Computer B, set the DISPLAY env variable to the public_ip of NAT router.
5. On Computer B run xclock.

At this point I'd expect to see an instance of xclock originating from Computer B onto my desktop. However this obviously won't work. The problem is that when the request is made to Computer B to forward the instance of xclock to Computer A the forwarded instance of xclock will get stuck at the NAT router. Without a port forwarding rule the NAT router will not know which internal IP to route the instance of xclock.

Here's my question. Is there any way for Computer A to initiate a connection to Computer B and then forward the instance of xclock? That way if it uses that same connection the NAT router will know which internal IP to route it to because it would be an active connection in the router's routing table. Or is there an alternative? Of course I can vnc into another computer outside the NAT network and then forward an X window to it just fine. But in the spirit of expanding my knowledge on X windows I'd like to see what is possible.

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Networking :: How To Open A Port - Failed To Open The TCP Port Number In The License

Jun 20, 2009

I am running lmgrd on CentOS5, but it returns Failed to open the TCP port number in the license. The port is 27000, how can I open that port?

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Fedora Networking :: Port Redirect, I.e. Whatever Comes Through Whatever Interface On Port AAAA Will Get Redirected To Port BBBB?

Feb 18, 2010

I want to do a simple port redirect, i.e. whatever comes trough whatever interface on port AAAA will get redirected to port BBBBI thought that iptables -t nat -I PREROUTING --source 0/0 --destination 0/0 -p tcp --dport AAAA -j REDIRECT --to-ports BBBBhowever it doesn't work, e.g. nc -v -w2 -z localhost AAAA gives:

nc: connect to localhost port AAAA (tcp) failed: Connection refused
while
nc -v -w2 -z localhost BBBB

[code]....

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Server :: Postfix Port - Send Message Via Port 587 Not Port 25

May 2, 2010

I have a mail server i need it to send message via port 587 not port 25, i make some changes to my postfix server which i use and it is already successed making a telnet to 587 port like it :

[Code]....

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Fedora Servers :: Can't Send My Outgoing Mail Using Port 587 / Why Is So?

Dec 10, 2009

I have installed a sendmail server on fedora 10
I try to configure my sendmail server as a mail server to send outgoing email using port 587( because port 25 is blocked). after finishing configuring my sendmail server, i checked out my sendmail server using telnet localhost 587, and it worked fine as below code...

I have tried two different ways for user name: name, or name@mail.mydomian.com, but not working at all, the two results are the same.
PS: I have test port 587 and can use port 587 and Kmail to send outgoing mail using other external relay server

is my wrong configuration for sendmail server or kmail?

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Red Hat / Fedora :: Changing Outgoing DNS (port 53) IP Address With Iptables?

Mar 31, 2009

I need to know what the Iptables "code" is to change the outgoing/Incoming IP for port 53 (DNS). I'm running CentOS on a dedicated server. I very familiar with Putty and SSH. So I don't need much details, I just can't figure this out. I asked my server providor but they deleted my ticket and didn't answer me.I tried this but am not sure if this correct of working?

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Ubuntu Networking :: Cannot Access Certain Ports Via Web Browser, Outgoing Port Blocked

Aug 12, 2011

I have a vps server running certain services which can be accessed via a web browser (e.g webmin control panel), but I have recently been unable to access these services from my home machine using Firefox 5.0, running ubuntu 11.04.

Example:

I can access the server on port 80 fine, eg: [URL]

However I cannot access my webmin control panel on: [URL]

The pages takes ages to load and then times out. Same with transmission-daemon on: [URL]

Everything is set up fine on my server, the ports are open in firewall etc. and I can access these pages fine from my work computer.

This has only started happening in the last day or two and had been working fine up till then. I have not messed around at all with the firewall on my home machine. I have tried other browsers besides Firefox with same result.

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Ubuntu :: DREADED Port Forwarding ?

Jan 24, 2010

I am having issues with the DREADED port forwarding. *why* is this important? *why* does it become such a chore to change? trying to run xlink kai on karmic. i have access to the routers in the house. the primary (#1) router is a standard issue Linksys, the other router is my DDWRT router which connects wirelessly to #1.

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Ubuntu :: How To Disable Port Forwarding

Oct 28, 2010

i have already changed the sshd_config file but anyone who logs in can access to the internet what should i do?

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Ubuntu Networking :: How To Ssh 9.10 Without Port Forwarding?

Nov 21, 2010

I have a ubuntu 9.10 on my desktop in my office and I have another ubuntu on my home desktop. Both machines are behind a router. I guess many people have already asked the same question: how to remote control the office desktop from my home desktop?Many posts discussed about solving this by setting up ssh and port forwarding. But my situation is that I cannot control the router in my office so I cannot set up any port forwarding for my office desktop. So I guess my question becomes how to remote control my office desktop without setting up any port forwarding on the office router.

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Ubuntu Networking :: SSH - VNC - No-IP And Port Forwarding

Mar 26, 2011

I currently use a commercial VPN when working overseas for secure internet access.

I now also need to VNC to a home ubuntu desktop (which runs software 24/7 that I need to periodically check).

When overseas, I use a Ubuntu laptop and an Android tablet.

For the VNC I intend to use an SSH tunnel. So my question is: should I ALSO set up openVPN on the home computer (so I can stop paying for a commercial provider which routes all my traffic twice across the Atlantic...) or is it easier/better to use the SSH tunnel for the secure webbrowsing too? Something like a SOCKS proxy?

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Server :: Port Forwarding For FTP?

Oct 21, 2010

my ftp (with SSL) server is behind firewall.

Code:81.81.81.81 FIREWALL (my external address) 192.168.1.5 - FTP server How to create portforwarding for such a configuration. I`m not interesting about iptables rules. I would like to know which port should I redirect and how ? FTP server usualy using 20 and 21. What about VSFTPD with SSL ? Also 20 and 21 ?

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CentOS 5 :: Can't Do Port Forwarding ?

Mar 5, 2011

I did local apache server at internal ip 192.168.1.2 and i wanna to do port forwarding to enter to it by my external ip address ?

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Ubuntu Networking :: Setting Time Delay For IPTables (Incoming / Outgoing Port)

Mar 9, 2010

I've got a box with 2 interfaces, with IP1 = 192.168.100.1 and IP2 = 10.1.1.1 respectively on them. I've got an iptables rule that looks like:
Code:
iptables -t nat -A POSTROUTING -s 192.168.100.0/24 -d 10.0.0.0/8 -p udp -j SNAT --to-source 10.1.1.1 --random

If I get 2 consecutive packets from the same address and port from 192.168.100.0/24, they get SNAT-ed and come out of the same port on 10.1.1.1. If then I get another packet from the same address and port 10 minutes later, then it gets SNAT-ed, but comes out of a different port on 10.1.1.1. My question is: how can I set the time delay I would like iptables to remember its incoming address/port to outgoing port mappings?

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Ubuntu Networking :: Terminate SSH Port Forwarding

Jan 31, 2010

I have a script to establish a reverse tunnel with other machine,My problem is to stop the tunnel. If I just kill the PID at sshtunnel.pids, ssh does not release the ports at the server side, so any new connection will fail for several minutes.Is there any way to signal SSH to exit gracefully?

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Ubuntu Security :: Dangers Of Port Forwarding?

Feb 4, 2010

Up to now I've been playing with Ubuntu whilst storing important data elsewhere for about 2 years. Now I'm ready to move to Ubuntu completely but want to address my security.I'm currently using a desktop and server behind a hardware firewall / Internet router. The router has DynDNS and forwards port 80 to the webserver and a port I picked at random to the desktop 22 for SSH with private keys. SSH passwords are disabled.

The first question is, is there a danger of running different security levels on the two machines? I don't care about the server, there is no data on it so I currently forward port 80 and am considering forwarding ports 631 (CUPS) and a port for LDAP. Will this effect my desktop (which has info I don't want to loose).The next question is whether port forwarding / hardware firewall is actually a safeguard against attack.

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Ubuntu Networking :: SSH Port Forwarding For Web Server

Feb 20, 2010

This should be easy but for some reason its not working. I don't have admin rights on one of my local networks to open the firewall for port 80 to make my server accessible remotely (from the internet). I have a remote server (OpenVZ VPS) and I want to port forward so that [url]:8080 will point to my localhost:80 from the internet itself (i can get it to work on the remote VPS server's local network)...

How could I accomplish this? Basically, I am trying to serve webpages from behind a firewall using a VPS as a hub.

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Ubuntu Networking :: Set Up Port Forwarding On Laptop?

May 6, 2010

would it be possible for anyone to give me step-by-step instructions on how to set up port forwarding on my laptop? I've been using Karmic Koala and just upgraded to Lucid Lynx and not really bothered to port-forward before, so not too sure where to start - googling gives me a lot of terms I don't understand.

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Ubuntu Security :: SSH Remote Port Forwarding

May 13, 2010

I'm trying to SSH into my home computer from a remote location outside of my house's LAN and can't figure out remote port fowarding.

The guide here says to use the following:

Code:

I've tried connecting to my home computer through many combinations of the syntax listed above, read the man file, and looked online for help. But can't find out the proper syntax or a good guide that isn't written for Windows users using Putty.

Let's assume for the sake of simplicity that the public IP address of my home SSH server is 123.123.123.123, the private IP address of my home SSH server is 192.168.1.100, my home SSH port is 2222, and the SSH port at my current location is is 22. How would I write out the command?

Every time I try to connect I get a "connection times out" error.

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Ubuntu Networking :: Two Nic Cards But No Port Forwarding?

Jul 6, 2010

I have two nic cards installed in a Lucid LTS server.

eth0 is static using
address 192.168.0.235
gateway 192.168.0.1
netmask 255.255.255.0

[Code]...

I have my Qwest DSL modem port forwarding port 80 to 192.168.3.235 however this doesn't seem to work if I have both cards running. If I remove the second card (eth1) and reconfigure eth0 to use 192.168.3.235 I can port forward into my webserver.

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