General :: Setup A Ssh Account With No Terminal But Port Forwarding?
Jan 29, 2011
I am trying to set up a new user account I can give to friends so they can SSH into my forward computer, and only allow forwarding of certain ports.
I do not want my friends to have a shell, or be able to change what ports to where they are allowed to forward.
example session: joe(friend) connects using PuTTY (that I have pre-set, he isn't good with computers) to example.com(my Internet facing computer) forwarding ports 8080,1990,25565 to him(with what ever end ports he wants, preferably they stay the same numbers) example ssh command to do similar (but he can still change the ports on my computer!)
ssh -N restricteduser@example.com -p443 -L8080:192.168.1.2:8080 -L1990:127.0.0.1:1990 -L25565:127.0.0.1:25565
is it possible to also leave default SSH functinality for all other users but this one?
I found this when I was searching google, but alas, I did not quite understand what was being suggested, and I don't think they covered restricting port forwarding
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Oct 2, 2010
How do I setup Self Port Forwarding on Fedora 13 x64 How Port Forwarding Works Port forwarding allows access to a local area network by a remote user through forwarding ports that provide ftp access and web server access. The operating systems use a kernel or ipfirewall to carry out the port forwarding process.
There are several different ways that port forwarding is accomplished. * Self Forwarding: Self forwarding is port forwarding that is accomplished on a local area network that has multiple computers connected to the network. Since all of the computers share the same IP address, the port forwarding must be conducted within each computer on its own system. If the local area network router has a network access translator then the computers that are connected to the router must also do port forwarding within their own system.Port forwarding can be accomplished with Unix systems however the port can only be accessed by the root administrator. This is a less common method of port forwarding due to the fact that using a root administrator poses risks to the system because the users will often take a detour to a higher port number to gain faster access to the server.Double port forwarding involves the use of multiple routers that join computers on a local area network. As a result, the ports on one router are forwarded to another router that acts as a gateway. The gateway router then forwards to a host on the local area network (LAN). This type of port forwarding involves the communication of several components which include the session server, session client, and session port. When the user establishes a connection the session server will connect to one of the session ports that are to be forwarded which will in turn, forward the port to the session client. Reverse port forwarding is used when access is required to a port that is protected behind a firewall.
While port forwarding is convenient, there are a few things to be aware of when using this type of technology. If you use port forwarding only one port can be used at a time and the machine that is receiving the port forwarding can only view the information as coming from the router instead of the original machine. Additionally, port forwarding can open up network access to other machines that may be able to find the port forwarding by gaining unauthorized access. I know how to setup port forwarding in my router along with Dyndns.org free ED, but my local area network has multiple computers connected to the network on my router. All of the computers share the same external (public) dynamic IP address; when I setup port forwarding only my Web Server can access the internet, so how do I setup Self Port Forwarding on Fedora 13 x64
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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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Jul 29, 2011
i need to setup port forwarding on my server (i have it running ubuntu 11.04 desktop) so i can host a minecraft server.
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May 13, 2010
I'm new to linux, but enjoy using it very much, especially without a GUI, console is fun! I need to set up port forwarding. We have 3 servers, 1x running Ubuntu server 8.04 (used as transparent proxy), 1x server 2003, 1x windows xp.
The linux box has the following ips:
eth0 (internal) 192.168.1.5
eth1 (external) 192.168.0.7
Windows server 2003:
192.168.1.6
Windows XP:
192.168.1.9
Router:
192.168.0.1
The router automatically forwards specific ports to 196.168.0.7 (Linux eth0). From there I want to forward port 8585 to 192.168.1.6 and 3000 to 192.168.1.9. Is there a way that I can do this using iptables?
The commands that I think I'm gonna use look like this:
iptables -A FORWARD -s 192.168.0.0/24 -p tcp --dport 8585 -d 192.168.1.6 -j ACCEPT
iptables -A FORWARD -s 192.168.0.0/24 -p tcp --dport 3000 -d 192.168.1.9 -j ACCEPT
Would this be a correct way of doing it? My biggest problem is that I can't test it without going live, and if I go live and something doesn't work, the entire building will be left without internet, people will hate me. Also, The proxy captures all data on port 80 and forwards it to 3128 so that the proxy can monitor the usage, and a few systems runs fine with it, others however can ping websites, and internet explorer says "website found, waiting for reply" but the webpages cannot be displayed.
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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
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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
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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
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6. I added 7869 for telnet service as follow;
Quote:
mytelnet 7869/tcp # My Telnet server
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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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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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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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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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Feb 1, 2010
I was having trouble setting up a db connection from my local machine to a db server that was configured to only accept connections from machines behind its own subnet. I had trouble setting up a multiple hop tunnel for chaining port forwarding through my firewall machine on the same subnet as the db. My first attempt involved two port forwards, on localhost and on the firewall machine, which didn't work for me. This approach I found at URL... involved constructing an end to end connection to the db via the firewall machine.
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May 10, 2011
- I setup port forwarding of openssh :
connect 1: ssh -g -f -p 11111 -i /<path-to-private-key> user1@ip-server1 -L 22222:ip-server1:161
- Then I setup second connection
connect 2: ssh -g -f -p 11111 -i /<path-to-private-key> user1@ip-server1 -L 22223:ip-server1:3306
- Openssh waring to me "bind: address already in use"
- So I think port 22223 have had another program use,I use command:
ps aux | grep ssh /* find process id of second connection */
kill -9 <process-id-second-connection>
netstat -an | grep 22223 /*find which program use port 22223> */
- but I can't find anywhat
- Then I run again command :
connect 2: ssh -g -f -p 11111 -i /<path-to-private-key> user1@ip-server1 -L 22223:ip-server1:3306
- And I receive a error from OpenSSH :" bind: address already in use"
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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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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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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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Jun 1, 2010
Im running a web server on port80, but i want traffic coming from ip 212.333.111.222 on port 80 to be fowarded to port 9020 on the same server that my web server is rinning at that is my sshd port
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May 12, 2010
am new to linux. i have an opensuse 10.2 mail server in my LAN. my users want every e-mail they receive to be forwarded to their web mails [URl]l.
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Feb 3, 2011
I use backtrack 4 in my acer aspire one notebook and i want to connect to my mail account from terminal!Could someone tell how can i do it??
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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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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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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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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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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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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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Jan 8, 2010
We have one linux machine in the office which happens to be an important firewall. I just know the basics and need to make one changeEssentially it is forward mysql traffic to another internal machine.This is the original rule (forward to 192.20.0.17) which is working
Code:
$IPTABLES -A tcp_packets -p TCP -s 0/0 --dport 3306 -j allowed
$IPTABLES -t nat -A PREROUTING -p TCP -i $INET_IFACE -d $STATIC_IP --dport 3306 -j DNAT -
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Mar 23, 2011
I have my mail application running on xxxx port in IPv6 and IPv4 enviornment on Linux machine (RHEL 5).I want to forward IPv4 request comming from windows client
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Aug 14, 2010
I have a CentOS box which is Internet Facing. It has 3 LAN's connected to it which are for virtual machines.
I want to port forward port 445 to a machine on one of the LAN interfaces. I have tried various ways to get it done, but still cannot access that port from the interface. I definately know device hosting port 445 is live, as I can ping it from the CentOS box and use lynx to access it! (It's a web server)
iptables -t nat -A PREROUTING -i eth0 -p tcp -m tcp --dport 445 -j DNAT --to-destination 192.168.0.2:445
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Jun 7, 2010
I've been Googling about port forwarding iptables and even though there's result and I've applied it in my script, I can't make iptables forwading request to another machine so I decided to ask help.
eth0 is my Internet Interface (1.2.3.4 is the public ip)
eth1 is my Lan Interface
eth2 is my DMZ Interface
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Feb 3, 2010
I have two PC's, one with slackware and one with arch, and I am trying to access the web server from the archlinux machine but i haven't manage to do that. The archlinux machine is connect to the internet via the slackware machine via a crossover cable:
internet > eth0 (pc1) and ppp0 (the PPPoE connection, pc1) > eth1 (pc1) > eth0 (pc2)
PC1:
ifconfig eth1 192.168.0.1 netmask 255.255.255.0
echo 1 > /proc/sys/net/ipv4/ip_forward
iptables -t nat -A POSTROUTING -o ppp0 -j MASQUERADE
iptables -A FORWARD -i ppp0 -o eth1 -m state --state RELATED,ESTABLISHED -j ACCEPT
iptables -A FORWARD -i eth1 -o ppp0 -j ACCEPT
pc2:
ifconfig eth0 192.168.0.2 netmask 255.255.255.0
ifconfig eth0 up
route add default gw 192.168.0.1 eth0
/etc/resolv.conf (The same DNS as the first PC)
And now the internet is working and on the archlinux machine, but I am not able to access the web server from LAN with a public IP. I tried many iptables port forwarding commands but none worked.
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