A little question to an SSH guru (port forwarding)
Linux - SoftwareThis forum is for Software issues.
Having a problem installing a new program? Want to know which application is best for the job? Post your question in this forum.
Notices
Welcome to LinuxQuestions.org, a friendly and active Linux Community.
You are currently viewing LQ as a guest. By joining our community you will have the ability to post topics, receive our newsletter, use the advanced search, subscribe to threads and access many other special features. Registration is quick, simple and absolutely free. Join our community today!
Note that registered members see fewer ads, and ContentLink is completely disabled once you log in.
If you have any problems with the registration process or your account login, please contact us. If you need to reset your password, click here.
Having a problem logging in? Please visit this page to clear all LQ-related cookies.
Get a virtual cloud desktop with the Linux distro that you want in less than five minutes with Shells! With over 10 pre-installed distros to choose from, the worry-free installation life is here! Whether you are a digital nomad or just looking for flexibility, Shells can put your Linux machine on the device that you want to use.
Exclusive for LQ members, get up to 45% off per month. Click here for more info.
A little question to an SSH guru (port forwarding)
I have the following setup:
serverA - internet - serverB - serverC
I do on serverA:
ssh -L10000:serverC:10000 serverB
This will connect localhost:10000 of serverA to serverC:10000.
Since the connection is made to localhost, it can only be used locally, on serverA itself (so far as I know).
Is there a way to establish the connection in a way that any machine close to serverA can make use of it?
i.e. to connect serverA:10000 to serverC:10000, so that any client (even if not having ssh) connecting to serverA:10000 would actually connect to serverC:10000?
I wonder, however, how this exactly works on internet gateways? I mean: does it forward port lo:10000, iif:10000, oif:10000, or all? (You might have found out: I would prefer oif:10000 not being forwarded)
Also if it is possible to allow GatewayPorts on a per-forwarding-basis, i.e. GatewayPorts should not be enabled for all port forwarding, only for specific ones.
As far as I know it needs to be on for all ports unless you run 2 sshd servers on different ports each with a different config. I also don't think there is a way to only bind to one interface so you'll need to use iptables to stop connections to the external interface.
LinuxQuestions.org is looking for people interested in writing
Editorials, Articles, Reviews, and more. If you'd like to contribute
content, let us know.