All of a sudden (read: without changing any parameters) my netbsd virtualmachine started acting oddly. The symptoms concern ssh tunneling.
From my laptop I launch:
$ ssh -L 7000:localhost:7000 user@host -N -v
Then, in another shell:
$ irssi -c localhost -p 7000
The ssh debug says:
debug1: Connection to port 7000 forwarding to localhost port 7000 requested. debug1: channel 2: new [direct-tcpip] channel 2: open failed: connect failed: Connection refused debug1: channel 2: free: direct-tcpip: listening port 7000 for localhost port 7000, connect from 127.0.0.1 port 53954, nchannels 3
I tried also with localhost:80 to connect to the (remote) web server, with identical results.
The remote host runs NetBSD:
bash-4.2# uname -a NetBSD host 5.1_STABLE NetBSD 5.1_STABLE (XEN3PAE_DOMU) #6: Fri Nov 4 16:56:31 MET 2011 root@youll-thank-me-later:/m/obj/m/src/sys/arch/i386/compile/XEN3PAE_DOMU i386
I am a bit lost. I tried running
tcpdump on the remote host, and I spotted these 'bad chksum':
09:25:55.823849 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto TCP (6), length 67, bad cksum 0 (->3cb3)!) 127.0.0.1.54381 > 127.0.0.1.7000: P, cksum 0xfe37 (incorrect (-> 0xa801), 1622402406:1622402421(15) ack 1635127887 win 4096 <nop,nop,timestamp 5002727 5002603>
I tried restarting the ssh daemon to no avail. I haven't rebooted yet - perhaps somebody here can suggest other diagnostics. I think it might either be the virtual network card driver, or somebody rooted our ssh.
$ ssh -L 7000:127.0.0.1:7000 user@host -N -v -v. (You can use "-v" up to 3 times to increase verbosity.) Also, is it possible that ssh was recently updated?
ssh -L 7000... -N -v -v(two v's) or
ssh -L 7000... -N -v -v -v.