我有一台远程机器（IPXX.XX.XX.XX) 运行一个用 python/cherrypy 编写的应用程序，该应用程序在环回接口上打开一个用于 http 连接的端口。如果我登录到远程计算机（使用 ssh），然后执行
curl http://127.0.0.1:8021
一切正常。但是，当我使用
ssh -L 6868:XX.XX.XX.XX:8021 -fN XX.XX.XX.XX
然后运行
curl http://localhost:6868
或者
curl http://127.0.0.1:6868
我收到此消息
curl: (52) Empty reply from server
ssh 在我创建隧道的终端中显示此消息
channel 2: open failed: connect failed: Connection refused
为了进行测试，我更改了应用程序以打开真实网络接口上的端口（XX.XX.XX.XX 而不是 127.0.0.1），然后从同一远程网络中的另一台机器使用 curl，结果成功了。然而，尝试在两台远程机器之间创建隧道时，得到的结果与在远程服务器和我的本地机器之间创建隧道时得到的结果相同。
我试图确保问题不是出在防火墙上，所以我运行了
iptables -A INPUT -d 127.0.0.1/32 -i lo -j ACCEPT
我认为这已经足够了，但我不确定。以下是 ssh -v 输出
[____@YYYY ~]$ ssh -vvL 6868:XX.XX.XX.XX:8021 -fN XX.XX.XX.XX
OpenSSH_5.4p1, OpenSSL 1.0.0-fips 29 Mar 2010
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: Applying options for *
debug2: ssh_connect: needpriv 0
debug1: Connecting to [XX.XX.XX.XX] port 22.
debug1: Connection established.
debug1: identity file /home/____/.ssh/id_rsa type -1
debug1: identity file /home/____/.ssh/id_rsa-cert type -1
debug1: identity file /home/____/.ssh/id_dsa type -1
debug1: identity file /home/____/.ssh/id_dsa-cert type -1
debug1: Remote protocol version 2.0, remote software version OpenSSH_5.4
debug1: match: OpenSSH_5.4 pat OpenSSH*
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_5.4
debug2: fd 3 setting O_NONBLOCK
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug2: kex_parse_kexinit: diffie-hellman-group-exchange-sha256,diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha1,diffie-hellman-group1-sha1
debug2: kex_parse_kexinit: [email protected],[email protected],ssh-rsa,ssh-dss
debug2: kex_parse_kexinit:
aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,[email protected]
debug2: kex_parse_kexinit:
aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,[email protected]
debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,[email protected],hmac-ripemd160,[email protected],hmac-sha1-96,hmac-md5-96
debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,[email protected],hmac-ripemd160,[email protected],hmac-sha1-96,hmac-md5-96
debug2: kex_parse_kexinit: none,[email protected],zlib
debug2: kex_parse_kexinit: none,[email protected],zlib
debug2: kex_parse_kexinit:
debug2: kex_parse_kexinit:
debug2: kex_parse_kexinit: first_kex_follows 0
debug2: kex_parse_kexinit: reserved 0
debug2: kex_parse_kexinit: diffie-hellman-group-exchange-sha256,diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha1,diffie-hellman-group1-sha1
debug2: kex_parse_kexinit: ssh-rsa,ssh-dss
debug2: kex_parse_kexinit:
aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,[email protected]
debug2: kex_parse_kexinit:
aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,[email protected]
debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,[email protected],hmac-ripemd160,[email protected],hmac-sha1-96,hmac-md5-96
debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,[email protected],hmac-ripemd160,[email protected],hmac-sha1-96,hmac-md5-96
debug2: kex_parse_kexinit: none,[email protected]
debug2: kex_parse_kexinit: none,[email protected]
debug2: kex_parse_kexinit:
debug2: kex_parse_kexinit:
debug2: kex_parse_kexinit: first_kex_follows 0
debug2: kex_parse_kexinit: reserved 0
debug2: mac_setup: found hmac-md5
debug1: kex: server->client aes128-ctr hmac-md5 none
debug2: mac_setup: found hmac-md5
debug1: kex: client->server aes128-ctr hmac-md5 none
debug1: SSH2_MSG_KEX_DH_GEX_REQUEST(1024<1024<8192) sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_GROUP
debug2: dh_gen_key: priv key bits set: 117/256
debug2: bits set: 510/1024
debug1: SSH2_MSG_KEX_DH_GEX_INIT sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_REPLY
debug1: Host 'XX.XX.XX.XX' is known and matches the RSA host key.
debug1: Found key in /home/____/.ssh/known_hosts:5
debug2: bits set: 514/1024
debug1: ssh_rsa_verify: signature correct
debug2: kex_derive_keys
debug2: set_newkeys: mode 1
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug2: set_newkeys: mode 0
debug1: SSH2_MSG_NEWKEYS received
debug1: Roaming not allowed by server
debug1: SSH2_MSG_SERVICE_REQUEST sent
debug2: service_accept: ssh-userauth
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug2: key: /home/____/.ssh/id_rsa ((nil))
debug2: key: /home/____/.ssh/id_dsa ((nil))
debug1: Authentications that can continue: publickey,gssapi-keyex,gssapi-with-mic,password,hostbased
debug1: Next authentication method: gssapi-with-mic
debug1: Unspecified GSS failure. Minor code may provide more information
Credentials cache file '/tmp/krb5cc_524' not found
debug1: Unspecified GSS failure. Minor code may provide more information
Credentials cache file '/tmp/krb5cc_524' not found
debug1: Unspecified GSS failure. Minor code may provide more information
debug2: we did not send a packet, disable method
debug1: Next authentication method: publickey
debug1: Trying private key: /home/____/.ssh/id_rsa
debug1: Trying private key: /home/____/.ssh/id_dsa
debug2: we did not send a packet, disable method
debug1: Next authentication method: password
[email protected]'s password:
debug2: we sent a password packet, wait for reply
debug1: Authentication succeeded (password).
debug1: Local connections to LOCALHOST:6868 forwarded to remote address XX.XX.XX.XX:8021
debug1: Local forwarding listening on ::1 port 6868.
debug2: fd 4 setting O_NONBLOCK
debug1: channel 0: new [port listener]
debug1: Local forwarding listening on 127.0.0.1 port 6868.
debug2: fd 5 setting O_NONBLOCK
debug1: channel 1: new [port listener]
debug1: Requesting [email protected]
debug1: Entering interactive session.
debug1: Connection to port 6868 forwarding to XX.XX.XX.XX port 8021 requested.
debug2: fd 6 setting TCP_NODELAY
debug2: fd 6 setting O_NONBLOCK
debug1: channel 2: new [direct-tcpip]
channel 2: open failed: connect failed: Connection refused
debug2: channel 2: zombie
debug2: channel 2: garbage collecting
debug1: channel 2: free: direct-tcpip: listening port 6868 for XX.XX.XX.XX port 8021, connect from 127.0.0.1 port 47048, nchannels 3
答案1
连接从您的服务器到 XX.XX.XX.XX:8021被拒绝。
如果将程序配置为监听环回接口，它将仅有的应答环回接口地址（127.0.0.1 和 ::1）上的连接，不是在同一台计算机拥有的任何其他地址上。
您需要使用：
ssh -L 6868:127.0.0.1:8021 -fN XX.XX.XX.XX
请注意，隧道目标是从 SSH 服务器的角度来看的。