带 Expect 的 Telnet 自动化：身份验证速度慢？

发布于 2024-11-05 10:08:02 字数 790 浏览 5 评论 0原文

我正在使用 Telnet 向 Mikrotik 路由器发送命令。

telnet 192.168.100.100 -l admin
Password: pass1234
[admin@ZYMMA] > /interface pppoe-server remove [find user=aspeed13]
[admin@ZYMMA] > quit

效果很好。

现在我想使用 Expect tcl 脚本自动执行它：

#!/usr/bin/expect --
spawn telnet 192.168.100.100
expect "Login:"
send "admin\r"
expect "Password:"
send "pass1234\r"
expect "\[admin@ZYMMA\] >"
send "/interface pppoe-server remove \[find user=aspeed13\]\r"
expect "\[admin@ZYMMA\] >"
send "quit\r"

它可以工作，但在身份验证（第 6 行：发送“pass1234\r”）之后，当路由器 CLI 加载时，它会冻结约 10 秒，并显示以下字符^[[?6c^[[24;3R 然后脚本运行正常。

我的问题是为什么 Telnet 在手动访问时加载速度很快，而在通过 Expect 脚本访问时则花费太多时间？我在有关 telnet 自动化的论坛上读到，他们说 telnet 很慢，但由于手动它太快了，为什么需要时间来加载期望？

原文

I'm sending a command to a Mikrotik router using Telnet.

telnet 192.168.100.100 -l admin
Password: pass1234
[admin@ZYMMA] > /interface pppoe-server remove [find user=aspeed13]
[admin@ZYMMA] > quit

It works fine.

Now I want to automate it using expect tcl script:

#!/usr/bin/expect --
spawn telnet 192.168.100.100
expect "Login:"
send "admin\r"
expect "Password:"
send "pass1234\r"
expect "\[admin@ZYMMA\] >"
send "/interface pppoe-server remove \[find user=aspeed13\]\r"
expect "\[admin@ZYMMA\] >"
send "quit\r"

It works, but after authentication (line 6: send "pass1234\r") when the Router CLI is loading it freezes for ~10seconds with the following characters ^[[?6c^[[24;3R
Then the scripts runs ok.

My question is why Telnet loads fast when accessed manually and it takes too much time when accessed via expect script? I read in forums about telnet automation they say telnet is slow, but since manually it's too fast why it takes time to load with expect?

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沫尐诺 2024-11-12 10:08:02

您所看到的是终端协商的反作用，这是因为您没有在真实终端中运行。（严格来说，您是 - 这是期望的魔力 - 但它的行为并不像普通终端那样。）

最简单的解决方法是在生成 telnet 会话之前将终端设置为其他内容，例如：

#!/usr/bin/expect --
set env(TERM) dumb
spawn telnet 192.168.100.100
# Rest of your script goes here ...

或者，您可以尝试正确响应进入 VT102 模式的请求和光标位置的报告（感觉工作量很大），或者您可以重写代码，以便它执行 interact 内的所有操作（这将另一端与您在其中运行的真实终端连接）。但如果设置一个环境变量可以解决这个问题，为什么还要这么麻烦呢？

（注意：我建议在这里将终端设置为“哑”，但关键是您需要最愚蠢的终端才能工作。哑终端是理想的选择，因为它们完全愚蠢，很容易冒充他们……）

What you're seeing is blow-back from terminal negotiation, which is because you're not running in a real terminal. (Strictly, you are – that's expect's magic – but it's not behaving as a normal terminal does.)

The easiest fix is to set the terminal to something else before spawning the telnet session, e.g.:

#!/usr/bin/expect --
set env(TERM) dumb
spawn telnet 192.168.100.100
# Rest of your script goes here ...

Alternatively, you could try to respond correctly to the request to enter VT102 mode and the report of the cursor location (which feels like a lot of work) or you could rewrite your code so that it does everything inside interact (which connects the other end with the real terminal that you're running inside). But if setting an environment variable fixes it, why go to all that extra hassle?

(NB: I suggest setting the terminal to dumb here, but the key is that you want the stupidest terminal that works. Dumb terminals are ideal, because they're just about totally stupid, making it easy to pretend to be them…)

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