我已经在所有客户端计算机和服务器之间建立了永久隧道大约一年了。据我所记得，我已经有几个月没有更新服务器或更改任何配置文件了。突然间，我所有客户端计算机的隧道都停止工作了（每个客户端计算机都使用不同的端口）。
我使用 RSA 密钥。我在每台计算机上都多次重新生成了它们。
我有一个脚本，当找不到“时，通过 Cron 作业运行以下命令[电子邮件保护]“在“ps aux”输出中：
ssh -p 2222 -g -T -N -x -f -R 2223:localhost:22 [email protected]
当我使用 -vvv 手动运行此命令时，我可以顺利通过 ssh 进入服务器，然后通过 ssh 进入转发端口 (ssh localhost -p 2223)。然而，五分钟后，它就挂了。我在服务器上使用 -vvv 获得以下输出：
chad@zeus:~$ ssh localhost -p 2223 -vvv
OpenSSH_4.7p1 Debian-8ubuntu1.2, 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 2223.
debug1: Connection established.
debug1: identity file /home/chad/.ssh/identity type -1
debug3: Not a RSA1 key file /home/chad/.ssh/id_rsa.
debug2: key_type_from_name: unknown key type '-----BEGIN'
debug3: key_read: missing keytype
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug2: key_type_from_name: unknown key type '-----END'
debug3: key_read: missing keytype
debug1: identity file /home/chad/.ssh/id_rsa type 1
debug1: identity file /home/chad/.ssh/id_dsa type -1
当我 telnet 到端口时，我得到
chad@zeus:~$ telnet localhost 2223
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
通常我会得到类似“SSH-2.0-OpenSSH_4.3”的输出。
在客户端，我启动了隧道（通过 ssh -p 2222 -g -T -N -x -f -R 2223:localhost:22[电子邮件保护]），我得到以下详细输出：
OpenSSH_5.1p1 Debian-5ubuntu1, 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 my.hostname [68.6.214.39] port 2222.
debug1: Connection established.
debug1: identity file /home/chad/.ssh/identity type -1
debug3: Not a RSA1 key file /home/chad/.ssh/id_rsa.
debug2: key_type_from_name: unknown key type '-----BEGIN'
debug3: key_read: missing keytype
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug2: key_type_from_name: unknown key type '-----END'
debug3: key_read: missing keytype
debug1: identity file /home/chad/.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/chad/.ssh/id_dsa type -1
debug1: Remote protocol version 2.0, remote software version OpenSSH_4.7p1 Debian-8ubuntu1.2
debug1: match: OpenSSH_4.7p1 Debian-8ubuntu1.2 pat OpenSSH_4*
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_5.1p1 Debian-5ubuntu1
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: ssh-rsa,ssh-dss
debug2: kex_parse_kexinit: aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,arcfour128,arcfour256,arcfour,aes192-cbc,aes256-cbc,[email protected],aes128-ctr,aes192-ctr,aes256-ctr
debug2: kex_parse_kexinit: aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,arcfour128,arcfour256,arcfour,aes192-cbc,aes256-cbc,[email protected],aes128-ctr,aes192-ctr,aes256-ctr
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-cbc,3des-cbc,blowfish-cbc,cast128-cbc,arcfour128,arcfour256,arcfour,aes192-cbc,aes256-cbc,[email protected],aes128-ctr,aes192-ctr,aes256-ctr
debug2: kex_parse_kexinit: aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,arcfour128,arcfour256,arcfour,aes192-cbc,aes256-cbc,[email protected],aes128-ctr,aes192-ctr,aes256-ctr
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-cbc hmac-md5 none
debug2: mac_setup: found hmac-md5
debug1: kex: client->server aes128-cbc 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: 120/256
debug2: bits set: 525/1024
debug1: SSH2_MSG_KEX_DH_GEX_INIT sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_REPLY
debug3: put_host_port: [68.6.214.39]:2222
debug3: put_host_port: [my.hostname]:2222
debug3: check_host_in_hostfile: filename /home/chad/.ssh/known_hosts
debug3: check_host_in_hostfile: match line 3
debug3: check_host_in_hostfile: filename /home/chad/.ssh/known_hosts
debug3: check_host_in_hostfile: match line 2
debug1: Host '[my.hostname]:2222' is known and matches the RSA host key.
debug1: Found key in /home/chad/.ssh/known_hosts:3
debug2: bits set: 534/1024
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: SSH2_MSG_SERVICE_REQUEST sent
debug2: service_accept: ssh-userauth
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug2: key: /home/chad/.ssh/id_rsa (0xb9b96ad0)
debug2: key: /home/chad/.ssh/identity ((nil))
debug2: key: /home/chad/.ssh/id_dsa ((nil))
debug1: Authentications that can continue: publickey,password
debug3: start over, passed a different list publickey,password
debug3: preferred gssapi-keyex,gssapi-with-mic,gssapi,publickey,keyboard-interactive,password
debug3: authmethod_lookup publickey
debug3: remaining preferred: keyboard-interactive,password
debug3: authmethod_is_enabled publickey
debug1: Next authentication method: publickey
debug1: Offering public key: /home/chad/.ssh/id_rsa
debug3: send_pubkey_test
debug2: we sent a publickey packet, wait for reply
debug1: Server accepts key: pkalg ssh-rsa blen 277
debug2: input_userauth_pk_ok: fp 14:ff:10:40:31:88:05:bc:46:73:91:ef:58:70:cc:78
debug3: sign_and_send_pubkey
debug1: Authentication succeeded (publickey).
debug1: Remote connections from LOCALHOST:2223 forwarded to local address localhost:22
debug1: Entering interactive session.
debug1: remote forward success for: listen 2223, connect localhost:22
debug1: All remote forwarding requests processed
我的.ssh 目录和文件的权限如下：
drwxr-xr-x 2 chad chad 4096 2009-10-15 00:03 .ssh
-rw-r--r-- 1 chad chad 408 2009-10-15 00:03 authorized_keys
-rw------- 1 chad chad 1675 2009-10-14 10:09 id_rsa
-rw-r--r-- 1 chad chad 393 2009-10-14 10:09 id_rsa.pub
-rw------- 1 chad chad 2210 2009-10-14 11:27 known_hosts
此外，如果我在客户端上“killall ssh”，然后 telnet 到端口 2223，我仍然会收到响应：
chad@zeus:~$ telnet localhost 2223
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
我彻底糊涂了。有人知道为什么会发生这种情况吗？
答案1
您的服务器周围的网络设置是否发生过任何变化？我曾见过这种情况，当流量经过的路由器或防火墙没有在没有流量时保持 TCP 连接的状态时，就会发生这种情况。
尝试将其添加到服务器上的 ssh_config：
ServerAliveInterval 60
这将每分钟通过 ssh 连接发送一些数据（它不会干扰您的隧道），这样无论发生什么超时，您的连接都不会忘记它。它还有一个额外的好处，就是如果它不再响应，它会自动终止您的 ssh 隧道，这将允许您现有的脚本重新连接。