To figure out whether perl module is installed at the system. Run:

perl -M<module_name> -e 1

if command return an error or NOT 0(zero) then module is not installed at the moment.

Here is also perl script which help you check a lot of modules:

#!/usr/local/bin/perl

my @modules = qw (put your modules here separated by space without any quotes);

foreach my $module (@modules){
print $module,"\t";
my $result=system("perl -M$module -e 1");
print "Installed" if (!$result);
print "\n";
}

EOF

My Perl script require several things :

1. Perl interpreter of course
2. IO::Socket perl module
3. Getopt::Long perl module

I will tell you nothing about first one. To install perl modules run cpan as root:

cpan -i Getopt::Long

and

cpan -i IO::Socket

When installation will be finished. Download bandtest.pl and save it at 1-st server.

Now go to the second one and run netcat(please make sure you have this package installed):

server02# nc -4tl 7777 > /dev/null

You can use any free port instead port 7777.

Back to first server and run bandtest.pl, but before make sure there is no any firewalls rules which hamper in connection between to hosts on port 7777.

Use telnet to check connection:

server01# telnet server02 7777
Connected to kivras01.
Escape character is '^]'.

This output means connection is successfully opened, so you can continue.

Make file with size for example 100Mb(I advice you to don’t use very big files, 100Mb is fit size which doesn’t fill your memory out and enough for proper results. I intentionally put file into memory before sending the data’s. This allow me delete any I/O operation during the network connection and as result prevent any result distortion.):

server01# dd if=/dev/zero of=/tmp/test bs=1024 count=1000000
100000+0 records in
100000+0 records out
102400000 bytes (102 MB) copied, 1.20234 s, 85.2 MB/s

Run bandtest.pl to get a results:

server01$ ./bandtest.pl -h server02 -p 7777 -f /tmp/test
Bytes were transfered 102.40 MB
Seconds taken: 8
Average speed 12.80 MB

EOF.

Let’s imagine that we have 2 hosts.

• Host A with user1 is your local host from which you will connect to remote.
• Host B with user2 is remote host where you want to log in as user2.

Run

ssh-keygen

as user1 on Host A to generate keys unless old one is exist. When I will be prompted to enter passphrase just keep it blank. This command generate RSA key with long in 2048 bit:

ssh-keygen -b 2048
Generating public/private rsa key pair.
Enter file in which to save the key (/home/user1/.ssh/id_rsa):
/home/user1/.ssh/id_rsa already exists.
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in /home/user1/.ssh/id_rsa.
Your public key has been saved in /home/user1/.ssh/id_rsa.pub.
The key fingerprint is:
9e:f0:44:4a:e2:81:72:02:0b:3c:b5:3d:be:a7:c2:95 user1@host_a
The key's randomart image is:
+--[ RSA 2048]----+
...
+-----------------+

After it’s done check content of your id_rsa.pub file:

host_a:~# cat .ssh/id_rsa.pub
ssh-rsa AAAAB3NzaC1yc2EAAAABIwAAAQEAzU6SlO7EZksPGmLTz3EcMpFQXME9otJ4vWqQ1Nnzd0g0FX5MS
/H1m2xJWCLfgsWTWyOP7hHQufPrzY5kqJkeF0tgOSPHnzDQt4YBE1Xi0ihR/cDK+KHOlIFG4kHlEs/ThTDpD0mwgBC755Tu5g2GOW3ogsrViZbyfa72HJQaEbISZwfiPnJUwmtGJ/+PQiEoN8cgK1zrk8oVnlguK0V52ZygFuvNKd6jmKIiDKOcQ2ZIobu6jYVd/Nit1gg+9llbuAdXDFn24AdNHatBzvlwb76yYa/ZAwZQKzytWca0NnMMwMeQ== user1@host_a

Copy it and log in remote Host B as user2. And append it to authorized_keys file:

$ cat >> /home/grytsenko/.ssh/authorized_keys
ssh-rsa AAAAB3NzaC1yc2EAAAABIwAAAQEAzU6SlO7EZksPGmLTz3EcMpFQXME9otJ4vWqQ1Nnzd0g0FX5MS
/H1m2xJWCLfgsWTWyOP7hHQufPrzY5kqJkeF0tgOSPHnzDQt4YBE1Xi0ihR/cDK+KHOlIFG4kHlEs/ThTDpD0mwgBC755Tu5g2GOW3ogsrViZbyfa72HJQaEbISZwfiPnJUwmtGJ/+PQiEoN8cgK1zrk8oVnlguK0V52ZygFuvNKd6jmKIiDKOcQ2ZIobu6jYVd/Nit1gg+9llbuAdXDFn24AdNHatBzvlwb76yYa/ZAwZQKzytWca0NnMMwMeQ== user1@host_a

Set proper permissions for file:

user2@host_b:~$ chmod 600 ~/.ssh/authorized_keys

Now you are ready to log in without password from Host A:

host_a~# ssh -p 443 user2@host_b
Linux host_b 2.6.18-5-686 #1 SMP Fri Jun 1 00:47:00 UTC 2007 i686

That’s all folks:).