使用crontab出现Host key verification failed的问题

假如我们现在有这样两台服务器，都用root登陆。

服务器1：vm01

服务器2：vm02

如何在vm01服务器中免密码登陆登陆vm02？我们使用ssh-keygen认证的方法。比如在ubuntu系统vm01服务器上，我们就可以用下面两个命令简单配置来实现。

ssh-keygen -t rsa -N ''
ssh-copy-id root@vm02

按照这个设置后，使用SecureCRT登陆服务器vm01，ssh测试登陆vm02成功。但是博主今天碰到一个奇怪的问题，在vm01中用crontab计划运行脚本传文件到vm02的时候出现了错误，log信息提示“Host key verification failed.” 。

为了找到具体错误原因，需要看下详细登陆信息，在脚本中添加ssh -vvv root@vm02，看是否可以登陆。最后找到错误如下：

OpenSSH_4.3p2, OpenSSL 0.9.8e-fips-rhel5 01 Jul 2008
Pseudo-terminal will not be allocated because stdin is not a terminal.
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: Applying options for *
debug2: ssh_connect: needpriv 0
debug1: Connecting to vm02[xxx.xxx.xxx.xxx] port 22.
debug1: Connection established.
debug1: permanently_set_uid: 0/0

...中间省略...

debug2: kex_parse_kexinit:
debug2: kex_parse_kexinit:
debug2: kex_parse_kexinit: first_kex_follows 0
debug2: kex_parse_kexinit: reserved 0
debug2: mac_init: found hmac-md5
debug1: kex: server->client aes128-cbc hmac-md5 none
debug2: mac_init: 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: 135/256
debug2: bits set: 513/1024
debug1: SSH2_MSG_KEX_DH_GEX_INIT sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_REPLY
debug3: check_host_in_hostfile: filename /root/.ssh/known_hosts
debug3: check_host_in_hostfile: filename /etc/ssh/ssh_known_hosts
debug3: check_host_in_hostfile: filename /root/.ssh/known_hosts
debug3: check_host_in_hostfile: filename /etc/ssh/ssh_known_hosts
debug3: check_host_in_hostfile: filename /root/.ssh/known_hosts
debug3: check_host_in_hostfile: filename /etc/ssh/ssh_known_hosts
debug2: no key of type 0 for host master
debug3: check_host_in_hostfile: filename /root/.ssh/known_hosts2
debug3: check_host_in_hostfile: filename /etc/ssh/ssh_known_hosts2
debug3: check_host_in_hostfile: filename /root/.ssh/known_hosts
debug3: check_host_in_hostfile: filename /etc/ssh/ssh_known_hosts
debug2: no key of type 2 for host master
debug1: read_passphrase: can't open /dev/tty: No such device or address
<strong>Host key verification failed.</strong>

从上面log中可以看到主要是这个错误，“debug1: read_passphrase: can’t open /dev/tty: No such device or address” 。因为crontab里的脚本不带任何用户定义的环境变量，所以最好在脚本开头调用一下这些变量。

博主就用env命令看了下当前成功登陆vm01系统的环境变量，然后把这些变量放到脚本开头就解决问题了。。。