我在公司网络中，想通过外部服务器 A 连接外部服务器。
本地 -> 代理 -> 服务器 A -> 服务器 B
我可以获得这个连接：
本地 -> 代理 -> 服务器 A
但是我无法通过隧道设置和代理设置连接到服务器 B。
是否WinSCP支持代理和隧道设置的连接？
代理设置在WinSCP：
type: HTTP
name: localhost
Port: 8888
SSH 隧道设置WinSCP：
Login data for server B
编辑：
日志数据：
. 2016-07-14 08:24:30.077 --------------------------------------------------------------------------
. 2016-07-14 08:24:30.093 WinSCP Version 5.7.7 (Build 6257) (OS 6.1.7601 Service Pack 1 - Windows 7 Enterprise)
. 2016-07-14 08:24:30.093 Configuration: HKCU\Software\Martin Prikryl\WinSCP 2\
. 2016-07-14 08:24:30.093 Log level: Normal
. 2016-07-14 08:24:30.093 Local account: local\user
. 2016-07-14 08:24:30.093 Working directory: C:\Program Files (x86)\WinSCP
. 2016-07-14 08:24:30.093 Process ID: 9628
. 2016-07-14 08:24:30.093 Command-line: "C:\Program Files (x86)\WinSCP\WinSCP.exe"
. 2016-07-14 08:24:30.109 Time zone: Current: GMT+2, Standard: GMT+1 (Mitteleuropäische Zeit), DST: GMT+2 (Mitteleuropäische Sommerzeit), DST Start: 27.03.2016, DST End: 30.10.2016
. 2016-07-14 08:24:30.109 Login time: Donnerstag, 14. Juli 2016 08:24:30
. 2016-07-14 08:24:30.109 --------------------------------------------------------------------------
. 2016-07-14 08:24:30.109 Session name: tunnel (Modified site)
. 2016-07-14 08:24:30.109 Host name: server-b.com (Port: 22)
. 2016-07-14 08:24:30.109 User name: ubuntu (Password: No, Key file: Yes)
. 2016-07-14 08:24:30.109 Tunnel: Yes
. 2016-07-14 08:24:30.109 Tunnel: Host name: server-a.com (Port: 22)
. 2016-07-14 08:24:30.109 Tunnel: User name: ubuntu (Password: No, Key file: Yes)
. 2016-07-14 08:24:30.109 Tunnel: Local port number: 0
. 2016-07-14 08:24:30.109 Transfer Protocol: SFTP
. 2016-07-14 08:24:30.109 Ping type: -, Ping interval: 30 sec; Timeout: 15 sec
. 2016-07-14 08:24:30.109 Disable Nagle: No
. 2016-07-14 08:24:30.109 Proxy: HTTP
. 2016-07-14 08:24:30.109 HostName: localhost (Port: 8888); Username: ; Passwd: No
. 2016-07-14 08:24:30.109 Send buffer: 262144
. 2016-07-14 08:24:30.109 SSH protocol version: 2 only; Compression: No
. 2016-07-14 08:24:30.109 Bypass authentication: No
. 2016-07-14 08:24:30.109 Try agent: Yes; Agent forwarding: No; TIS/CryptoCard: No; KI: Yes; GSSAPI: Yes
. 2016-07-14 08:24:30.109 GSSAPI: Forwarding: No; Server realm:
. 2016-07-14 08:24:30.109 Ciphers: aes,blowfish,3des,WARN,arcfour,des; Ssh2DES: No
. 2016-07-14 08:24:30.109 KEX: dh-gex-sha1,dh-group14-sha1,dh-group1-sha1,rsa,WARN
. 2016-07-14 08:24:30.109 SSH Bugs: A,A,A,A,A,A,A,A,A,A,A,A
. 2016-07-14 08:24:30.109 Simple channel: Yes
. 2016-07-14 08:24:30.109 Return code variable: Autodetect; Lookup user groups: A
. 2016-07-14 08:24:30.109 Shell: sudo su -
. 2016-07-14 08:24:30.109 EOL: 0, UTF: 2
. 2016-07-14 08:24:30.109 Clear aliases: Yes, Unset nat.vars: Yes, Resolve symlinks: Yes
. 2016-07-14 08:24:30.109 LS: ls -la, Ign LS warn: Yes, Scp1 Comp: No
. 2016-07-14 08:24:30.109 SFTP Bugs: A,A
. 2016-07-14 08:24:30.109 SFTP Server: default
. 2016-07-14 08:24:30.109 Local directory: default, Remote directory: home, Update: Yes, Cache: Yes
. 2016-07-14 08:24:30.109 Cache directory changes: Yes, Permanent: Yes
. 2016-07-14 08:24:30.109 DST mode: 1
. 2016-07-14 08:24:30.109 --------------------------------------------------------------------------
. 2016-07-14 08:24:30.155 Opening tunnel.
. 2016-07-14 08:24:30.155 Autoselected tunnel local port number 50000
. 2016-07-14 08:24:30.218 [Tunnel] Looking up host "ec2-52-29-233-82.eu-central-1.compute.amazonaws.com"
. 2016-07-14 08:24:30.218 [Tunnel] Connecting to 127.0.0.1 port 8888
. 2016-07-14 08:24:45.545 [Tunnel] Waiting for data timed out, asking user what to do.
. 2016-07-14 08:24:45.545 Asking user:
. 2016-07-14 08:24:45.545 **Host is not communicating for 15 seconds.
. 2016-07-14 08:24:45.545
. 2016-07-14 08:24:45.545 Wait for another 15 seconds?** ()
. 2016-07-14 08:24:48.569 [Tunnel] Closing connection.
. 2016-07-14 08:24:48.569 [Tunnel] Sending special code: 12
* 2016-07-14 08:24:48.631 (EFatal) **Terminated by user.**
要离开公司网络，我必须使用代理。