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我有一个 dnssec 区域，想使用 sshfp 发布 ssh 密钥。

因此，在拥有密钥的主机上，我运行：

 ssh-keygen -r localhost

这给了我结果：

 localhost IN SSHFP 1 1 223458a4e3f4cae23a2365a127a9fc5dbfc4df0b
 localhost IN SSHFP 1 2 cf04e11c129c465e90afc3fc68b0a9c6f256e7c3dc2f0ef0d61557f5848cc2bb

然后我将它放在我的 dnssec 区域（显然是正确的主机名），退出该区域并通过 dig 查询进行检查。一切安好。

然后，一个 ssh 查询说事情是错误的：

  stephane@luciole:~$ ssh -v -o VerifyHostKeyDNS=yes host
  OpenSSH_6.6.1, OpenSSL 1.0.1i 6 Aug 2014
  debug1: Reading configuration data /home/stephane/.ssh/config
  debug1: /home/stephane/.ssh/config line 1: Applying options for host
  debug1: Reading configuration data /etc/ssh/ssh_config
  debug1: /etc/ssh/ssh_config line 19: Applying options for *
  debug1: Connecting to host [2001:16d8:d0:205::5]
  debug1: Connection established.
  debug1: identity file /home/stephane/.ssh/id_rsa type 1
  debug1: identity file /home/stephane/.ssh/id_rsa-cert type -1
  debug1: identity file /home/stephane/.ssh/id_dsa type -1
  debug1: identity file /home/stephane/.ssh/id_dsa-cert type -1
  debug1: identity file /home/stephane/.ssh/id_ecdsa type -1
  debug1: identity file /home/stephane/.ssh/id_ecdsa-cert type -1
  debug1: identity file /home/stephane/.ssh/id_ed25519 type -1
  debug1: identity file /home/stephane/.ssh/id_ed25519-cert type -1
  debug1: Enabling compatibility mode for protocol 2.0
  debug1: Local version string SSH-2.0-OpenSSH_6.6.1p1 Debian-7
  debug1: Remote protocol version 2.0, remote software version OpenSSH_6.6
  debug1: match: OpenSSH_6.6 pat OpenSSH_6.5*,OpenSSH_6.6* compat 0x14000000
  debug1: SSH2_MSG_KEXINIT sent
  debug1: SSH2_MSG_KEXINIT received
  debug1: kex: server->client aes128-ctr hmac-md5-etm@openssh.com none
  debug1: kex: client->server aes128-ctr hmac-md5-etm@openssh.com none
  debug1: sending SSH2_MSG_KEX_ECDH_INIT
  debug1: expecting SSH2_MSG_KEX_ECDH_REPLY
  debug1: Server host key: ECDSA 4d:57:c1:77:2d:cf:6b:46:d4:83:24:3c:b7:d4:0d:67
  debug1: found 4 insecure fingerprints in DNS
  debug1: mismatching host key fingerprint found in DNS
  @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
  @    WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED!     @
  @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
  IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!
  Someone could be eavesdropping on you right now (man-in-the-middle attack)!
  It is also possible that a host key has just been changed.
  The fingerprint for the ECDSA key sent by the remote host is
  4d:57:c1:77:2d:cf:6b:46:d4:83:24:3c:b7:d4:0d:67.
  Please contact your system administrator.
  Update the SSHFP RR in DNS with the new host key to get rid of this message.
  debug1: checking without port identifier
  The authenticity of host '[host] ([2001:16d8:d0:205::5])' can't be established.
  ECDSA key fingerprint is 4d:57:c1:77:2d:cf:6b:46:d4:83:24:3c:b7:d4:0d:67.
  No matching host key fingerprint found in DNS.
  Are you sure you want to continue connecting (yes/no)?

那我为什么会有？

我现在在安全的环境中工作，本地网络可以直接访问服务器。没有 MITM 可能。

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1 回答 1

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创建 dns sshfp 时，我没有注意到我只有四个 sshfp RR，而我有三个 ssh 密钥（每个密钥两个 sshfp）。

于是我将ssh目录下的sshfp返回并一一生成，并与我在dns中的对比。看来我没有 ecdsa 密钥。

所以我专门用这个密钥生成了 sshfp。在该区域注册并签名。之后，当我尝试使用 VerifyHostKeyDNS 和详细信息进行 ssh 连接时，ssh 说它建立了正确的 ssh 指纹！

cd /etc/ssh
ls
ssh_config
ssh_dsa_key
ssh_dsa_key.pub
...

ssh-keygen -r host -f ssh_host_ecdsa_key
于 2014-09-25T20:54:24.027 回答