You can fordward ports from userspace using netcat like this:
nc -l -p $localport -c "nc $remotehost $remoteport"
Example:
nc -l -p 8888 -c "nc example.com 8888"
Caution: This starts a new process for ever connect to the port.
Jonas Wagner
Software Engineer
Zürich, Switzerland
More about me
guitarmasterclass.net (guitar lessons)
Hey Jonas, are you sure that this version of nc is that same as the BSD version? Under linux I don't have the "-c" command line option. Any ideas?
Comment by heretoo — 5/21/09 9:11 AM | # - re
Okay, I figured it out. There are several versions of netcat. Under ubuntu I have the two variants "openbsd" and "traditional" (nc 1.10 which has a buffer overflow in it). Well, I think I'll forward ports some other way.
Comment by heretoo — 5/21/09 9:34 AM | # - re
hi there, i'm stuck with this problem:
I need to forward traffic from a local tcp port to another tcp in the same machine... like tcp 8080 to tcp 81. Can i use netcat to do that??
Something like:
nc -l -p 8080 -c "nc 127.0.0.1 81"
Thanks in advance...
Comment by caesar — 8/26/09 4:16 PM | # - re
I think this should work. Although if you are using linux I think you are better of if you use iptables.
Comment by Jonas Wagner — 8/26/09 8:08 PM | # - re
Hi there!! It's me again. I want to explain why i need "something" to forward a local port to another local port...
I use Java ICA Client Applet to connect via SSL-Tunnels to my Citrix Metaframe XP Server... ICA server listens by default on port tcp 1494 and it doesn't allow me to set a listening port range. When i set up the java ica client, i cannot open 2 SSL-tunnels over the same port(1494), and if i set another SSL-tunnel over other port than 1494 the client cannot connect to de ICA Server. So if i redirect tcp port 1495 traffic to tcp 1494 then i guess i'll be able to set up ssl-tunnels over other ports than 1494 forwarding them locally to itself.
Comment by caesar — 8/26/09 7:04 PM | # - re