有关ssh的疑问

我虚拟机机子是ubuntu8.04 刚装了openssh 想从windows访问linux
不过我在虚拟机里测试ssh时，有问题。如下：
我在终端中敲入 ssh localhost 返回 read from socked failed: connection reset by peer
我debug得到的结果是 ： ssh -vvv localhost

OpenSSH_4.6p1 Debian-5ubuntu0.6, OpenSSL 0.9.8g 19 Oct 2007
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: Applying options for *
debug2: ssh_connect: needpriv 0
debug1: Connecting to localhost [127.0.0.1] port 22.
debug1: Connection established.
debug1: identity file /home/listar/.ssh/identity type -1
debug1: identity file /home/listar/.ssh/id_rsa type -1
debug1: identity file /home/listar/.ssh/id_dsa type -1
debug1: Remote protocol version 2.0, remote software version OpenSSH_4.6p1 Debian-5ubuntu0.6
debug1: match: OpenSSH_4.6p1 Debian-5ubuntu0.6 pat OpenSSH*
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_4.6p1 Debian-5ubuntu0.6
debug2: fd 3 setting O_NONBLOCK
debug1: SSH2_MSG_KEXINIT sent
Connection closed by UNKNOWN

请大家帮忙看下，这个是为什么呢?