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From: | Richard Neill |
Subject: | [Qemu-devel] Re: user-net -redir working? [problem located] |
Date: | Tue, 22 Nov 2005 22:04:32 +0000 |
User-agent: | Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7.12) Gecko/20050920 |
Re: User-net not working: > Disabling the Nagle algorithm (i.e., enabling TCP_NODELAY) or typing a > lot of garbage just to fill the buffer with enough data can help, > also.> > And IIRC, netcat has a UDP mode as well. I see no reason for this to> happen, but is there any chance it's using UDP by default, and you're > only redirecting TCP?> > Good luck!Thanks for your message.I think that -redir really is broken: I've also been unsuccessful in trying to make it work using an FTP server on a Windows guest, and using the SSH server on a knoppix guest. Has anyone here ever had success with it? It also fails on hosts with 2 different versions of Mandrake.Anyway, I've taken your suggestion, and run both ends with ethereal. Here's what I did:HOST (Linux); qemu -cdrom /dev/cdrom -boot d -user-net -redir tcp:2200::22 GUEST (Knoppix): Boot up, then start sshd. Verify that I can indeed do ssh address@hidden, and that PermitRootLogin is yes in sshd_config. Then, start ethereal (on the "any" interface) HOST: Start ethereal (on the "any" interface") ssh -p 2200 address@hidden At this point, ssh just stalls. It's obviously waiting for something, but not known what. I get no output at all from it.
Can you try "ssh -p 2200 root@<my IP address not localhost> I've run into this several times dealing with the -redir function, especially since localhost resolves as 127.0.0.1. On my Solaris host with a linux guest, the packet arriving showed up as 127.0.0.1, which ended up with the same behavior as you're describing. --------------- Dear Ben,Good guess! That's an ingenious bit of debugging, and it now works perfectly. I suppose that now means 3 things need to be done:
1)Figure out *why* it doesn't work. It's definitely QEMU-specific, since if I run 2 separate netcat processes on the host, I have no problem. I'd be interested to know why this occurs. In particular, is it a problem with the user-net stuff on the host, or a problem with the guest?
2)Fix it... :-)3)Document this on the website as a known bug, so Google can find it. Currently, anyone using an earlier version will just think that qemu is broken. It hasn't worked since at least 0.6.1, although I can't tell you about earlier versions.
I suspect that I am not up to the task of (2), so I must defer to the experts...
Best wishes, Richard
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