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I have a compressed file size of about 9.5 GB and want to transfer from one server to another server, I tried to use like the below,
server2:
nc -lp 1234 > file.tar.gz
server1:
nc -w 1 1234 < file.tar.gz
its not working.
I tried so many ways.
One machine is CentOS 6.4 and the other one is Ubuntu 12.04 LTS
Thanks in advance.
On receiving end:
nc -l 1234 > file.tar.gz
On sending end:
cat file.tar.gz | nc <reciever's ip or hostname> 1234
That should work. Depending on the speed, it may take a while but both processes will finish when the transfer is done.
From the nc(1) man page:
-l Used to specify that nc should listen for an incoming connection rather than initiate
a connection to a remote host. It is an error to use this option in conjunction with
the -p, -s, or -z options.
So your use of -p is wrong.
Use on server2:
nc -l 1234 > file.tar.gz
And on server1:
nc server2 1234 < file.tar.gz
from the sender
nc -v -w 30 1337 - l < filename
where "-v" from verbose, "-w 30" for a wait before and after 30 sec for the connection, "1337" port number, "-l" tell nc that this is a sender
from the receiver
nc -v -w 2 ip_add_of_sender 1337 > filename
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when I use docker run -itd mysql,then to use ps -elf check the process infomation with "4 S systemd+ 257584 257561 1 80 0 - 712611 poll_s Jul17 ? 00:40:16 mysqld".
root#xx:/proc/257584/ns# ps -elf | grep mysqld
4 S systemd+ 257584 257561 1 80 0 - 712611 poll_s Jul17 ? 00:40:20 mysqld
root#xx:/proc/257584/ns# ps -el | grep mysqld
4 S 999 257584 257561 1 80 0 - 712611 poll_s ? 00:40:21 mysqld
But I use "cat /cat/passwd" can't find username equal to "systemd+".
docker Version: 20.10.12
os ubuntu20.04
ps (sadly) trims the username to 8 (if i'm counting right) characters and adds a + after the user name initial part. The username could be systemd-mysql or systemd-something that you can find in passwd.
From manual:
If the length of the username is greater than the length of the display column, the username will be truncated. See the -o and -O formatting options to customize length
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First of all, Here is my environment of system:
# cat /proc/version
Linux version 4.15.0-52-generic (buildd#lgw01-amd64-051) (gcc version 7.3.0 (Ubuntu 7.3.0-16ubuntu3)) #56-Ubuntu SMP Tue Jun 4 22:49:08 UTC 2019
# cat /etc/issue
Ubuntu 18.04.2 LTS \n \l
Refer to this Ubuntu Wiki, ubuntu has used Systemd by default since 15.04 and Systemd runs with PID 1 as /sbin/init. However, I found the different result on my ubuntu 18.04:
# ps aux | awk '$2==1{print $0}'
root 1 0.0 0.8 159692 8784 ? Ss Oct24 0:21 /sbin/init noibrs splash
# lsof -p 1 | grep txt
systemd 1 root txt REG 252,1 1595792 927033 /lib/systemd/systemd
So, my question is that:
Why Ubuntu 18.04 use /sbin/init instead of /lib/systemd/systemd?
Why lsof -p 1 | grep txt return /lib/systemd/systemd while the process of PID 1 is /sbin/init?
/sbin/init is a symbolic link to /lib/systemd/systemd
Take a look at the output of stat /sbin/init or readlink /sbin/init
This is what they mean by systemd "running as /sbin/init". The systemd binary is linked as /sbin/init and started by that link name.
Update
To further explain the difference between the ps and lsof output: ps is showing the command that started the process, while lsof is showing which files a process has opened.
When systemd was started, it was called by /sbin/init noibrs splash, the file system resolved the link to the file /lib/systemd/systemd which was then read from disk and executed.
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I using fail2ban v.0.8.2 but I can't unban an IP:
with fail2ban-client I see IP:
fail2ban-client status fail2ban
Status for the jail: fail2ban
|- filter
| |- File list: /var/log/fail2ban.log
| |- Currently failed: 1
| `- Total failed: 8
`- action
|- Currently banned: 2
| `- IP list: 151.10.65.197 151.10.72.169
`- Total banned: 2
from man page should be sufficiently do:
fail2ban-client get fail2ban actionunban 151.10.65.197
output of command does not return error but:
iptables -L -nv |grep -b2 -a1 151
16262- pkts bytes target prot opt in out source destination
16351: 0 0 DROP all -- * * 151.10.72.169 0.0.0.0/0
16440: 0 0 DROP all -- * * 151.10.65.197 0.0.0.0/0
16529- 181K 48M RETURN all -- * * 0.0.0.0/0 0.0.0.0/0
and the output of
fail2ban-client status fail2ban
is same of above, hence command does not run.
You need to use fail2ban-client get jail-name actionunban ipaddress That will allow you to unban an IP address. Use iptables -L -n to find the status of the correct jail-name to use?. The command you are giving: fail2ban-client get fail2ban actionunban xxx.xxx.xxx.xxx is correct given your output. Check status again to make sure it has not already been unblocked by the timeout. That would explain why the command fails.
Here is a good page Fail2ban Manual Unban Single Host (for iptables) There have been changes to the unban procedure syntax (get/set) depending on version.
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I'm connected to a private network where the IP addresses are like 192.168.xxx.xxx. I know the IP address of the default gateway but how do I get the gateway mac address? I'm working on iMac and Linux machines. Any Unix command for that?
This gives you list of everything:
netstat -rn
or this one to get default gateway:
netstat -rn | grep 'default'
WHAT YOU REALLY WANT:
netstat -rn | grep 'default' | awk '{print $2}'
Here the command line example for arping assuming your gateway's IP address is 192.168.1.1 and you have connected over eth0:
arping -f -I eth0 192.168.1.1
ARPING 192.168.1.1 from 192.168.1.24 eth0
Unicast reply from 192.168.1.1 [ab:cd:ef:01:02:03] 1.030ms
Sent 1 probes (1 broadcast(s))
Received 1 response(s)
So in this case gateway's MAC address is ab:cd:ef:01:02:03
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I used netcat in the following way
nc -l 3333 //for server
nc 127.0.0.1 3333 // for client
With this I am able to use it as a two way chatting system.
My question is, then why is there another option
-p ( -p source_port Specifies the source port nc should use, subject to privilege restrictions and availability.)
It works with -p option too. What is the difference between the two?
A TCP connection consists of two TCP endpoints, each consisting of an IP address and a TCP port. The client usually chooses a random port, although you can force netstat to use a given port using the -p option.
Try:
adi#laps:~$ nc -l 3333 -p 4444
nc: cannot use -p and -l
adi#laps:~$ nc -l 3333 &
[1] 6025
adi#laps:~$ nc localhost 3333 -p 3333
nc: bind failed: Address already in use