检查SSH隧道是否已启动并正在运行

I have a perl script which, when destilled a bit, looks like this:

我有一个perl脚本,当有点蒸馏时,看起来像这样:

my $randport = int(10000 + rand(1000));          # Random port as other scripts like this run at the same time
my $localip = '192.168.100.' . ($port - 4000);   # Don't ask... backwards compatibility
system("ssh -NL $randport:$localip:23 root\@$ip -o ConnectTimeout=60 -i somekey &");    # create the tunnel in the background

sleep 10;       # Give the tunnel some time to come up

# Create the telnet object
my $telnet = new Net::Telnet(
        Timeout =>      10,
        Host    =>      'localhost',
        Port    =>      $randport,
        Telnetmode =>   0,
        Errmode =>      \&fail,
);

# SNIPPED... a bunch of parsing data from $telnet

The thing is that the target $ip is on a link with very unpredictable bandwidth, so the tunnel might come up right away, it might take a while, it might not come up at all. So a sleep is necessary to give the tunnel some time to get up and running.

问题是目标$ ip是在带有非常不可预测的带宽的链路上,因此隧道可能会立即出现,可能需要一段时间,它可能根本不会出现。因此,需要睡眠才能让隧道有一段时间起床和跑步。

So the question is: How can i test if the tunnel is up and running? 10 seconds is a really undesirable delay if the tunnel comes up straight away. Ideally, i would like to check if it's up and continue with creating the telnet object once it is, to a maximum of, say, 30 seconds.

所以问题是:我如何测试隧道是否正常运行?如果隧道立即出现,10秒是非常不希望的延迟。理想情况下,我想检查它是否已启动并继续创建telnet对象一次,最多为30秒。

Edit: Ping doesn't help me mouch, as the remote end of the tunnel is generally up, but with a very high amount of packetloss

编辑:Ping不能帮助我mouch,因为隧道的远端通常是up,但是有很多的数据包丢失

Solved: Extrapolating from the tip suggested by mikebabcock, sleep 10 has been replaced with this block which works like a charm:

解决:从mikebabcock提出的提示推断,睡眠10已经取代了这个像魅力一样的块:

my $starttime = time();
while (1)
{
    # Check for success
    if (system("nc -dzw10 localhost $randport > /dev/null") == 0) { last }

    # Check for timeout
    if (time() > $starttime + 30) { &fail() }

    # 250ms delay before recheck
    select (undef, undef, undef, 0.25);
}

3 个解决方案

#1

Use netcat -- often nc on Linux systems:

在Linux系统上使用netcat - 通常是nc:

nc -dvzw10 ${HOSTNAME} 23

Works for me, with a response like:

对我有用,回复如下:

Connection to ${HOSTNAME} 23 port [tcp/telnet] succeeded!

It also returns 0 on success, and is happy with a simple connection after which it goes away.

它也会在成功时返回0,并且对一个简单的连接感到满意,之后它就会消失。

-d means not to read anything from the keyboard side

-d表示不从键盘端读取任何内容

-v means to be verbose (turn this off in a script)

-v表示冗长(在脚本中将其关闭)

-z means to disconnect after making the connection

-z表示在建立连接后断开连接

-w10 means to wait up to 10 seconds, otherwise give up

-w10表示等待最多10秒,否则放弃

#2

You can integrate a ping to your ssh server and if it works fine the ssh tunnel is up

您可以将ping集成到您的ssh服务器,如果它正常工作,则ssh隧道已启动

# only a ping sample :-D
if !  ping -c 1 192.168.101.9
then
        echo ":-("
else
        echo ":-)"
fi

#3

I think fping might be better then the usual ping, more script friendly.

我认为fping可能比通常的ping更好,脚本更友好。

fping -t 60000 [your server]

fping -t 60000 [你的服务器]

should try to connect to the server 60seconds before giving up Something like

应该尝试在放弃之前60秒连接到服务器

if(fping -t 60000 [your server]) {
execute desired code;
} else {
execute this script again to rerun;;
}

I think you get the idea even if the coding isn't real.

即使编码不真实,我认为你也能得到这个想法。

#1