特殊情况 ssh 连接延迟

Question

设置

我们办公室有一个 DMZ 和 LAN，它们通过以下设置连接到外部：

+------+
|      |------> LAN (normal office router)
|Modem |
|      |------> DMZ (a single machine)
+------+

我们的互联网帐户是 Comcast 的，我们有 5 个状态 IP，其中一个指向 DMZ 中的单台机器。

问题

ssh 连接在任何地方启动，除了办公室 LAN真的很快。但是，从 LAN 来看，大约有 5 秒的延迟。跆拳道？？

额外信息

DMZ 机器是 debian 5。

wget对 DMZ执行 a没有延迟。

执行以下操作时，所有内容都会HERE IS WHERE THE LAG IS INCURRED立即执行。

ssh -vvvv sam@dmz.com

...
debug2: set_newkeys: mode 1
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug3: Wrote 16 bytes for a total of 1015
debug2: set_newkeys: mode 0
debug1: SSH2_MSG_NEWKEYS received
debug1: SSH2_MSG_SERVICE_REQUEST sent
debug3: Wrote 48 bytes for a total of 1063
debug2: service_accept: ssh-userauth
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug2: key: /home/shopkins/.ssh/id_rsa (0x22440830)
debug2: key: /home/shopkins/.ssh/identity ((nil))
debug2: key: /home/shopkins/.ssh/id_dsa ((nil))
debug3: Wrote 64 bytes for a total of 1127`


HERE IS WHERE THE LAG IS INCURRED


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/shopkins/.ssh/id_rsa
debug3: send_pubkey_test
debug2: we sent a publickey packet, wait for reply
debug3: Wrote 368 bytes for a total of 1495
debug1: Authentications that can continue: publickey,password
debug1: Trying private key: /home/shopkins/.ssh/identity
debug3: no such identity: /home/shopkins/.ssh/identity
debug1: Trying private key: /home/shopkins/.ssh/id_dsa
debug3: no such identity: /home/shopkins/.ssh/id_dsa
debug2: we did not send a packet, disable method
debug3: authmethod_lookup password
debug3: remaining preferred: ,password
debug3: authmethod_is_enabled password
debug1: Next authentication method: password
sam@dmz.com's password:

Answer 1

很可能必须等待反向 DNS 查找超时/失败。

尝试在/etc/ssh/sshd_config 中设置它（假设您使用的是默认安装的 openssh），看看是否能解决您的问题。

UseDNS no