Linux Networking

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The variety of Linux distributions creates myriad issues relating to configuration and operations when computers are networked, not the least of which is the use of various network management applications, some of which are included with specific distributions, while others are standalone applications.

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I am trying to mount drives using autofs. There are 3 directories that I want to mount: home, data, and web. The mount for /home works but data and web don't work. When I mounted /data and /web manually, the shares showed up. Below has the log:
Jun 10 11:09:18 testdaviddo13 automount: Starting automounter version 5.0.7-99.el7, master map auto.master
Jun 10 11:09:18 testdaviddo13 automount: using kernel protocol version 5.02
Jun 10 11:09:18 testdaviddo13 automount: lookup_nss_read_master: reading master files auto.master
Jun 10 11:09:18 testdaviddo13 automount: do_init: parse(sun): init gathered global options: (null)
Jun 10 11:09:18 testdaviddo13 automount: spawn_mount: mtab link detected, passing -n to mount
Jun 10 11:09:18 testdaviddo13 automount: spawn_umount: mtab link detected, passing -n to mount
Jun 10 11:09:18 testdaviddo13 automount: lookup_read_master: lookup(file): read entry /home
Jun 10 11:09:18 testdaviddo13 automount: lookup_read_master: lookup(file): read entry /web
Jun 10 11:09:18 testdaviddo13 automount: lookup_read_master: lookup(file): read entry /data
Jun 10 11:09:18 testdaviddo13 automount: lookup_read_master: lookup(file): read entry /misc
Jun 10 11:09:18 testdaviddo13 automount: lookup_read_master: lookup(file): read entry /-
Jun 10 11:09:18 testdaviddo13 automount: lookup_read_master: lookup(file): read entry +auto.master
Jun 10 11:09:18 testdaviddo13 automount: lookup_nss_read_master: reading master files auto.master
Jun 10 11:09:18 …
0
C++ 11 Fundamentals
LVL 13
C++ 11 Fundamentals

This course will introduce you to C++ 11 and teach you about syntax fundamentals.

I have a scenario where I need a load balancer
When a new tcp connection is initiated from the client, the load balancer much assign a server, and always route all traffic from that that to the server it initially picked

When I netstat, I see and ipaddress and port for the client. (connection) so it makes sense to use this as the identifier for that client

Is there any software in exisitance to do this? Or do. I need to write my own?
0
I have executed the following command on a red hat Linux server
rpm -qa --last 

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to try and determine when the latest updates/patches were applied to the server. I ran this under the context of a non root account but still got some output.

A couple of questions:
--will the output of this command be full/accurate if it was executed under the context of a none root account.
---Secondly, how often are updates issued for red hat Linux, and are they cumulative / is it similar to Microsoft patch releases, and do the updates also cover security vulnerabilities. The last updates listed in the output of command were 2017 which raises some concerns that security bugs have not been patched, and therefore the server is vulnerable.
----Finally, does red hat Linux have a support lifecycle where they only continue to issue patches for certain versions, and if so where can I see where the version currently operated sits in this support lifecycle, e.g. is it still eligible for updates for new bugs/vulnerabilities.
0
Hello,
I am trying to install and SSL certificate on a website after i've migrated it from Ubuntu to a CentOS server.
Everything is up and running but I can't get SSL working. Apache starts fine. My config test shows no errors. But when I try to connect to the server through ssl, in all browsers I get ERR_CONNECTION_REFUSED. I don't believe its an SSL issue but maybe a firewall. I don't know as im unfamiliar with CENTOS, Any ideas?
0
I have been running Ubuntu 14 with custom tcp tuning parameters for a couple years.  I applied, via puppet, all of the same tuning parameters, but on Ubuntu 18, my TCP Time Wait is very high.  What is the best method of finding the source of this high TCP Time Wait?  The process that is using the tcp connections is a java application.

Please let me know any other information I should provide.

Graph on the left is Ubuntu 18.04, right is Ubuntu 14.04

Thank you,

Reade
tcp-time-wait.png
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Hi everyone,

I'm searching for a tool to manage and monitor hundreds of Unix servers.
90% are on Debian but from Debian 7 to Debian 9.

I tried Cockpit and I really liked it but it is limited to 20 servers.
Webmin is not good enough.
I tried to install a CentOS server with SpaceWalk on it but I can't take the control of Debian's servers.

So I would like to know if you have some advice for me.

Tank you all.
0
I am running centos 6 and have been having issues getting a kaseya agent installed.
0
Hi expert

What is the command to check the status of the IPSec in rehat linux 7 ?
0
I just installed Ubuntu server 18 and trying to get netplan to take my static IP but not having luck.

Can someone assist me with this?

This what I entered but it's not working.

netplan
0
I am using an older version of oxidized (rancid) to grab configs. It was build by someone else about three years ago. I'm trying to find where you configure the user ID and password to be used by the different network equipment. I don't see a reference to a user in /home/oxidized/.config/oxidized/config and not even a reference to device type PanOS which is what I'm aiming for.
0
Learn Ruby Fundamentals
LVL 13
Learn Ruby Fundamentals

This course will introduce you to Ruby, as well as teach you about classes, methods, variables, data structures, loops, enumerable methods, and finishing touches.

I have some SLES 12.2 server where I need to monitor certain network traffic for diagnosing a problem that occurs every now an then. I'll try to record the traffic with tcpdump, and when that problem arises, I could dissect the correcponding network traffic with Wireshark.

I've set up a main script which contains
#!/bin/bash
tcpdump -iany -G $((30*60)) -n -w tcpdump.io.%F_%H%M%S.pcap -z ./tcpdump_postproc.sh net 192.168.1.0/24 or net 192.168.2.0/24 > tcpdump.statistics
./tcpdump_postproc.sh

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and a helper script tcpdump_postproc.sh for some postprocessing:
#!/bin/bash
gzip *.pcap
find . -maxdepth 0 -mmin +$((12*60)) -name '*.pcap.gz' -delete

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I'd expect that script to run indefinitely, creating capture files containing 30 minutes of data each, until I stop tcpdump with i.e. [CTRL-C] or kill. The postprocessing called after stopping (and whenever a new capture file is created) will zip the created capture files and limit the backlog of capture files to 12 hours.

So far, so good. Now to the problem:

tcpdump stops capturing data in the middle of the second file and exits (without error, as far as I could see).

What have I missed ?
0
Hi guys

We have an Linux instance in the cloud with Nginx installed on it. However, whenever the server restarts, the Nginx services don't. I'm not overly familiar with Linux commands. Can anyone help me how we can automate the Nginx services to start on restarts automatically?

Thanks for helping
Yash
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While setting up a PXE boot server on a CentOS 7 machine, I encountered a strange problem with TFTP. I cannot retrieve any files from the TFTP server without encountering a timeout problem. The boot process comes so far that I correctly get an IP address and a file name from the DHCP server. However, when the boot files are to be retrieved from the TFTP server, a "TFTP open timeout" message comes. If I manually make a TFTP connection to the PXE server from a local computer, I immediately get access to the server. But if I try with a "get pxelinux.0" command, I get another timeout message.
My firewall is set up correctly and it also makes no difference if I completely turn off the firewall. SeLinux is also disabled.
If I make a tcpdump on port 69 I get the following message:
12:34:33.477401 IP 172.16.1.202.ah-esp-encap > tools.dmz.tuxme.dk.tftp:  27 RRQ "pxelinux.0" octet tsize 0
12:34:35.481131 IP 172.16.1.202.acp-port > tools.dmz.tuxme.dk.tftp:  27 RRQ "pxelinux.0" octet tsize 0
12:34:39.490793 IP 172.16.1.202.msync > tools.dmz.tuxme.dk.tftp:  27 RRQ "pxelinux.0" octet tsize 0
12:34:45.477712 IP 172.16.1.202.gxs-data-port > tools.dmz.tuxme.dk.tftp:  27 RRQ "pxelinux.0" octet tsize 0
12:34:53.441801 IP 172.16.1.202.vrtl-vmf-sa > tools.dmz.tuxme.dk.tftp:  27 RRQ "pxelinux.0" octet tsize 0
12:35:03.384065 IP 172.16.1.202.newlixengine > tools.dmz.tuxme.dk.tftp:  32 RRQ "pxelinux.0" octet blksize 1456
12:35:39.414843 IP 172.16.1.202.newlixconfig > 

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0
zgrep -C5 'xyz' abc.gz

i have above grep
in the results how to search on say "error code=1111 description=null pointer"


Above results too large i am not able to copy paste to notepad++ (which i usually do makes easy to to my eyes) to search on like error code=1111 description=null pointer"

zgrep -C5 'xyz' abc.gz >>/home/TestUser/testuser.txt

can we do tail or head on above?
please advise
0
Hi Experts,

     I want to configure elasticsearch to a new IP address.  Currently, it is on a dev machine.  But I want to configure to a new IP address.

currently, in my elasticsearch.yml the current settings are

network.host:0.0.0.0

path.data : /var/lib/elasticsearch

path.logs: /var/logs/

inside /var/lib/  elasticsearch is link file to links to /mnt/elasticsearch

I want to install elasticsearch to new machine.  machine ipaddress is eg., 5*.25*.22*.1*,  

My questions are,

Do I have to install elastic search on this new IP address,

or can I set this new IP address as network.host path in the existing dev machine?

or do I have backup and restore to the new ipaddress?

Please suggest how to configure?

I had tried changing the network host to the new IP address, and copied elasticsearch folder to the new machine and set the path to path.data and I had set path.logs to new machine folder paths and restarted elastic search from the existing dev machine.

elastic search failed to start.

Please suggest how to configure the elastic search on this new machine.

With many thanks,

Bharath AK
0
i am using mputty to connect to unix box.

i see black screen with while log messages

i like to change to white bacground screen with black letter on top

please advise
0
Are there instructions somewhere for setting up VPN on Ubuntu via command line?

Anyone can provide any reference please?  Thank you!!
0
Hello,
I have open vpn server and all client work fine
I have also setup a new open vpn client config on it and its connect to the other servers.
I want when the client request a specific ip to route through vpn client connection that is established on server
so what I have to do in this case.
thanks.
0
i have removed below pid file using rm command as i got some error messages with permissions on that

rm xyz.pid

is there is a way i can restore that file

I am trying to start the web logic server and having issues which used to work earlier file

Please advise
0
OWASP Proactive Controls
LVL 13
OWASP Proactive Controls

Learn the most important control and control categories that every architect and developer should include in their projects.

to run below script to start web logic
/opt/scripts/bea_start admin
after login i cannot directly execute
i have to go to below directory to execute

cd /xyz/home/user123/opt/def/bea_domains/12/xyz_dev1/servers/xyz_dev1_admin/logs

i though below is absolute path and as soon as i login i should be able to run from
/opt/scripts/bea_start admin

also i have to run as admin only not as my user id

why i cannot run as soon as i login from root directory(if i am not mistaken that is what i go as soon as i login)

also how to see who all can run the script and how to change that script permission so that even if i login i can execute not just admin

Please advise
0
I have just provisioned a Debian 9 VM.

My /etc/network/interfaces file reads

auto ens32

iface ens32 inet static
	address 172.16.50.210
	netmask 255.255.255.0
	broadcast 172.16.50.254
	network 172.16.50.0
	gateway 172.16.50.254

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Yet for some reason, I end up with the system having one DHCP address and the static one I'd like for the file above.

I'm sure I am missing something obvious... but what??
0
zgrep 'MobileDevice' xyz_1.log.20181121.gz|grep 'USER123'| awk '$0>= "2018-Nov-21 00:01" && $0<="2018-Nov-21 23:59"' | awk -F '|' '$24>300 {print}'

zgrep 'MobileDevice' xyz_2.log.20181121.gz|grep 'USER123'| awk '$0>= "2018-Nov-21 00:01" && $0<="2018-Nov-21 23:59"' | awk -F '|' '$24>300 {print}'

zgrep 'MobileDevice' xyz_3.log.20181121.gz|grep 'USER123'| awk '$0>= "2018-Nov-21 00:01" && $0<="2018-Nov-21 23:59"' | awk -F '|' '$24>300 {print}'

i am using above 3 separate greps one after other on 3 types of jvm files

how to combine them as one

zgrep 'MobileDevice' xyz_?.log.20181121.gz|grep 'USER123'| awk '$0>= "2018-Nov-21 00:01" && $0<="2018-Nov-21 23:59"' | awk -F '|' '$24>300 {print}'
i tried above which did not work
i tried below that also did not work


zgrep 'MobileDevice' xyz_*.log.20181121.gz|grep 'USER123'| awk '$0>= "2018-Nov-21 00:01" && $0<="2018-Nov-21 23:59"' | awk -F '|' '$24>300 {print}'
please advise
0
zgrep 'MobileDevice' xyz.log.20181121.gz|grep 'USER123'| awk '$0>= "2018-Nov-21 00:01" && $0<="2018-Nov-21 23:59"' | awk -F '|' '$24>300 {print}'
above grep printing all the columns successfully satisfying abov condition of

$24>300


Now i need to filter above query based on the state like Florida which is printing in 23rd column i.e $23

zgrep 'MobileDevice' xyz.log.20181121.gz|grep 'USER123'| awk '$0>= "2018-Nov-21 00:01" && $0<="2018-Nov-21 23:59"' | awk -F '|' '$23=FLORIDA {print}'

above query not working

how to check String equality in AWK

Please advise
0
Hi,



 while adding ubuntu to vitual box after removing centos there getting attached error
i am using windows 10 hp laptop currently


please advise how resolve this error.



thanks in advance
ERRuBUNTU.png
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zgrep 'xyz'  abc.log.2018111212| grep '|[1-9][0-9][0-9][0-9][0-9]|0000' | wc -l

i am trying to figure out what above grep doing?

what is meaning of
|[1-9][0-9][0-9][0-9][0-9]|0000

wc -l means some kind of word count?
what is -l

any good links or resources or video tutorials to master greps and awk and sed end to end to debug server logs?

please advise
0

Linux Networking

18K

Solutions

15K

Contributors

The variety of Linux distributions creates myriad issues relating to configuration and operations when computers are networked, not the least of which is the use of various network management applications, some of which are included with specific distributions, while others are standalone applications.

Top Experts In
Linux Networking
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