在非标准端口上通过 ssh 建立隧道，因为我必须在端口 10401（它是“svnserve”）上的远程服务器上运行 svn，所以我在关于协议 2.0 的日志行应该是之前遇到了问题：
本地框 unname：Linux localbox 3.0.0-14-generic #23-Ubuntu SMP Mon Nov 21 20:28:43 UTC 2011 x86_64 x86_64 x86_64 GNU/Linux
Remote box unname (server name changed to 'foo'): Linux foo 2.6.32.27-grsec #5 SMP Thu Dec 30 01:24:01 PST 2010 i686 unknown unknown GNU/Linux
christopherbalz@localbox:~$ svn co --username=christopherbalz svn+ssh10401://foo.bar.com/baz
OpenSSH_5.8p1 Debian-7ubuntu1, OpenSSL 1.0.0e 6 Sep 2011
debug1: Reading configuration data /home/christopherbalz/.ssh/config
debug1: Applying options for foo.bar.com
debug1: Applying options for foo.bar.com
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: Applying options for *
debug1: Connecting to foo.bar.com [208.95.105.37] port 10401.
debug1: Connection established.
debug1: identity file /home/christopherbalz/.ssh/id_rsa type 1
debug1: Checking blacklist file /usr/share/ssh/blacklist.RSA-2048
debug1: Checking blacklist file /etc/ssh/blacklist.RSA-2048
debug1: identity file /home/christopherbalz/.ssh/id_rsa-cert type -1
debug1: identity file /home/christopherbalz/.ssh/id_rsa type 1
debug1: Checking blacklist file /usr/share/ssh/blacklist.RSA-2048
debug1: Checking blacklist file /etc/ssh/blacklist.RSA-2048
debug1: identity file /home/christopherbalz/.ssh/id_rsa-cert type -1
< hangs here forever >
相比之下，一个普通的 ssh 到这个服务器会给出与上面相同的日志加上这个（还有更多，这里没有粘贴），就在日志挂在上面的位置：
debug1: Remote protocol version 2.0, remote software version OpenSSH_5.8
debug1: match: OpenSSH_5.8 pat OpenSSH*
debug1: Enabling compatibility mode for protocol 2.0
. . .
由于'protocol 2.0'日志紧随其后，我想知道在svn+ssh下日志中提到的兼容模式是否有问题？如果是这样，如何解决这个问题？如果不是，可能是什么原因导致此挂起？