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 running centos 6 and have been having issues getting a kaseya agent installed.
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Learn Ruby Fundamentals
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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.

Hi expert

What is the command to check the status of the IPSec in rehat linux 7 ?
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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
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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.
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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 ?
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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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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
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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
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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
Angular Fundamentals
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Angular Fundamentals

Learn the fundamentals of Angular 2, a JavaScript framework for developing dynamic single page applications.

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

Anyone can provide any reference please?  Thank you!!
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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
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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
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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??
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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
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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
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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
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Our Solaris 10 server running Weblogic are getting thousands of messages below:
Intermittently the OS would freeze:  no core/crash dumps found.

Does this require a WL or Solaris patch or certain TCP tuning?  


Feb  5 06:17:27 VGUV30 ip: [ID 995438 kern.warning] WARNING: High TCP connect timeout rate! System (port 8080) may be under a SYN flood attack!
Feb  5 12:13:03 VGUV30 ip: [ID 995438 kern.warning] WARNING: High TCP connect timeout rate! System (port 8080) may be under a SYN flood attack!
Feb  6 10:28:25 VGUV30 ip: [ID 995438 kern.warning] WARNING: High TCP connect timeout rate! System (port 8080) may be under a SYN flood attack!
Feb  6 11:56:35 VGUV30 ip: [ID 995438 kern.warning] WARNING: High TCP connect timeout rate! System (port 8080) may be under a SYN flood attack!
Feb  7 21:57:33 VGUV30 ip: [ID 995438 kern.warning] WARNING: High TCP connect timeout rate! System (port 8080) may be under a SYN flood attack!
Feb  7 22:06:34 VGUV30 ip: [ID 995438 kern.warning] WARNING: High TCP connect timeout rate! System (port 8080) may be under a SYN flood attack!
Feb  8 04:24:08 VGUV30 ip: [ID 995438 kern.warning] WARNING: High TCP connect timeout rate! System (port 8080) may be under a SYN flood attack!
Feb  9 21:28:25 VGUV30 ip: [ID 995438 kern.warning] WARNING: High TCP connect timeout rate! System (port 8080) may be under a SYN flood attack!
Feb  9 22:12:10 VGUV30 ip: [ID 995438 kern.warning] WARNING: High TCP connect timeout rate! System (port 8080) may be …
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Build an E-Commerce Site with Angular 5
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Build an E-Commerce Site with Angular 5

Learn how to build an E-Commerce site with Angular 5, a JavaScript framework used by developers to build web, desktop, and mobile applications.

Dear Experts
We are having web based CRM application running on LAMP stack web server and data base servers are running two different server. Our software developers have decided to create indexes based on their analysis due to slow queries observations, the database server is mysql 5.4 version.
As it is production server the indexing will affect the work and also the tables size is huge and overall database size is 65GB. Please suggest the best practice, following is the approach can think about but again not sure if this is best recommended but there is a challenge as mentioned, please suggest on how such cases are handled.
1.Setup new webserver and mysql server with same config and same versions and take backup of production server database and import it to the new database server and create indexes and test, this process may take few days to week and by the time indexing gets completed which may take few days during this period production server database would have undergone changes as users are working on production instance, can you please suggest the best way to handle this.
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Previously when we transferred a 20GB gz  Solaris file down to PC's
local HDD & then from the local PC HDD, transfer to a USB HDD, our
DLP corrupted the gz file when it's transferred from local HDD to USB

We have since resolve that but to prevent untoward corruption in
future for copying of critical files to USB HDD,

Q1:
Does Winscp has checksum feature that checks at Unix end & at
PC end?

Q2:
If so I would rather use Winscp to transfer directly to USB HDD.
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unix server keep sign out after 1 minute or so on production.

is there is a way i can run some process like

tail -f xyz.gz
to keep continuous rolling until i cancel that so that it wont sign out on me while i focus on some other work  for 30 miinutes and come back it should not signout
please advise
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On a Redhat Linux system running a bash shell script I need some help with an if then statement that has more than 2 conditions. I basically want to check for this
A AND B or C  
A AND B or D
A AND B or E

Something along these lines but it doesn't work and wondered if I have the correct usage of brackets. It's not what's contained for evaluation that's the issue it's the syntax of the AND and OR where there's more than two conditions that I am struggling with.

if [[ $(find /opt/app -name httptd*.conf | grep -v grep | grep -c http) -eq 0 ] && [ ! -f /etc/init.d/apache ] ||  [ $(find /app -name http*.conf | grep -v grep | grep -c http) -eq 0 ]] || \
[[ $(find /opt/app -name httptd*.conf | grep -v grep | grep -c http) -eq 0 ] && [ ! -f /etc/init.d/apache ] ||  [ $(find /application -name http*.conf | grep -v grep | grep -c http) -eq 0 ]] || \
[[ $(find /opt/app -name httptd*.conf | grep -v grep | grep -c http) -eq 0 ] && [ ! -f /etc/init.d/apache ] ||  [ $(find /application -name manifest* | grep -v grep | grep -c http) -eq 0 ]] ; then
.....
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Dear Experts

We are running web server (10.253.18.41) which is on lamp stack and database server mysql is on another server 10.253.12.42, users are complaining the application is taking too long time also on prospect conversion takes too much time and finally timeout approx 3 mins then time out , when check the network statics below is the continuous report, please let me know what does this indicate, what could be the solution

tcp        0      0 10.253.18.41:38760          10.253.12.42:3306           TIME_WAIT
tcp        0      0 10.253.18.41:38765          10.253.12.42:3306           TIME_WAIT
tcp        0      0 10.253.18.41:38274          10.253.12.42:3306           TIME_WAIT
tcp        0      0 10.253.18.41:38130          10.253.12.42:3306           TIME_WAIT
tcp        0      0 10.253.18.41:38590          10.253.12.42:3306           TIME_WAIT
tcp        0      0 10.253.18.41:38116          10.253.12.42:3306           TIME_WAIT
tcp        0      0 10.253.18.41:39296          10.253.12.42:3306           TIME_WAIT
tcp        0      0 10.253.18.41:38577          10.253.12.42:3306           TIME_WAIT
tcp        0      0 10.253.18.41:38379          10.253.12.42:3306           TIME_WAIT
tcp        0      0 10.253.18.41:39027          10.253.12.42:3306           TIME_WAIT
tcp        0      0 10.253.18.41:38827          10.253.12.42:3306           TIME_WAIT
tcp        0      0 10.253.18.41:38222          10.253.12.42:3306           TIME_WAIT
tcp        0     …
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Dear Experts

CRM system work flow triggers emails to the prospect email account as and when the prospect statues changes via the SMTP server ( without password that is without authentication as it is Relay server hosted locally-office 365 mail protection ). We could see the connection to the email server getting established but no packets sent/received , but through telnet we can send and receive mails by making use of from and to email commands through the telnet session, can you help where the things are going wrong. following SL2 cases it works but SL3 it does not work.
1. though telnet to the smtp server with FROM and TO commands it works that is mail is delivered to the TO addressed account.
2. though CRM system configure email settings with email account, smtp and port without the SMTP authentication mail is getting delivered to the To account.
3. CRM system through workflow trigger email on each status changes mail is not getting delivered instead we can see connection is ESTABLISHED to the smtp server
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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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