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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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
0
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grep "testing" 789.log

zgrep "testing"  123.gz

i like to redirect above production server output to
abc/def/test.txt file which is on some other system test server where i have access

how to do it
grep "testing" 789.log >> abc/def/test.txt
above gives error no such directory as that directory is not there in production server

grep "testing" 789.log
how above different from
grep -C2 "testing" 789.log

i see below time stamp lines came 3 of them when i use -C2
2019-Jan-17 04:50:51.198 EST

i see below time stamp lines came 3 of them when i did not use -C2
2019-Jan-17 04:50:51.198 EST

please advise
WithC2.png
WithoutC2.png
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when i do ls -ltr i see bunch of .gz files says 123.gz and 456.gz
and bunch of no gz files say 789.log etc

how to grep on say "testing" on both zip gz files and non zip files

grep "testing" 789.log

zgrep "testing"  123.gz

not sure how to combine above two together

also how search today log between 10 am to 11 am for that "testing" word in log?
please advise
0
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 > 

Open in new window

0
I am trying to learn iptables and virtualbox.

I have 3 Centos7 VMs configured as follows with iptables configured on VM2. All interfaces are configured as "host only adapter" in virtual box as /24 networks:


VM1 - - - - - - - - -  - - VM2- - - - - - - - - - -VM3
192.168.1.1             192.168.1.2
                                  172.16.0.2             172.16.0.1
                                                                  10.0.0.1

iptables is configured on VM2 as follows:

LINE 1: -A INPUT -s 192.168.1.1 -d 192.168.1.2 -j LOG
LINE 2: -A FORWARD -s 192.168.1.1 -d 172.16.0.2 -j LOG
LINE 3: -A FORWARD -s 192.168.1.1 -d 172.16.0.1 -j LOG
LINE 4: -A FORWARD -s 192.168.1.1 -d 10.0.0.1 -j LOG

When I send data using scapy -- send(IP(src="n.n.n.n", dst="y.y.y.y")/TCP()) -- the traffic flow described on LINES 1, 2 and 4 is logged. But the flow from LINE 3 is not.

I have tried LINE 3 using INPUT and OUTPUT rules without success.

What am I missing?

Thanks.
Steve
0
Dear Experts,
 
I have a following setup:
 
[list]Home LAN connected to the Internet on 10.0.0.0[/list]
[list]Lab/Test LANs on 192.168.30.x & 192.168.40.x[/list]
[list]VMnet3 for .30 and VMnet4 for .40[/list]
 
I would like some of the machines in the Lab/Test LANs to access the Internet, so I'd tried to setup a router.. without having any success so far
 
Router (RHEL6.9):
eth0 = 10.0.0.100/24, GW: 10.0.0.1
eth1 = 192.168.30.254/24
eth2 = 192.168.40.254/24
 
#netstat -nr
Destination     Gateway         Genmask         Flags   MSS Window  irtt Iface
10.0.0.0        0.0.0.0         255.255.255.0   U         0 0          0 eth0
192.168.30.0    0.0.0.0         255.255.255.0   U         0 0          0 eth1
192.168.40.0    0.0.0.0         255.255.255.0   U         0 0          0 eth2
169.254.0.0     0.0.0.0         255.255.0.0     U         0 0          0 eth0
169.254.0.0     0.0.0.0         255.255.0.0     U         0 0          0 eth1
169.254.0.0     0.0.0.0         255.255.0.0     U         0 0          0 eth2
0.0.0.0         10.0.0.1        0.0.0.0         UG        0 0          0 eth0
 
Desktop on .30 (also RHEL6.9)
eth0 = 192.168.30.16/24, GW: 192.168.30.254
 
#netstat -nr
Destination     Gateway         Genmask         Flags   MSS Window  irtt Iface
192.168.30.0    0.0.0.0         255.255.255.0   U         0 0          0 eth0
0.0.0.0         192.168.30.254  0.0.0.0         UG        0 0          0 eth0
 
I can ping the GW at …
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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
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
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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
"smbpasswd -a user" makes samba server unavailable.

Previously used Debian 7 without problems. Reinstalled and set up Debian 9.

I have atttached my smb.conf. This is a fresh installation. When using the config as attached here, I can browse to my server via \\ip-address and \\netbiosname windows 10 machine, but none of the shares are available. I get a password promptwhen trying to access the shares, and then a message that I am not authorized.So then, I add the system user 'atle' to samba:
smbpasswd -a atle

This prompts me for a password twice. I enter the same password twice, all ok.

Then:
systemctl  restart smbd
systemctl  restart nmbd

Then I try to browse \\ip-address and \\netbiosname from my windows 10 machine, but no response. The server seems unavailable.
"systemctl smbd status" responds all is well. Trying to list shares from the command prompt with smbclient to \\ip-address works fine.

I then perform:
smbpasswd -x atle
systemctl restart smbd
systemctl restart nmbd

Now I can browse \\ip-address and \\netbiosname from my windows 10 machine again.

So, what is going on here? How to fix?
smb.conf
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
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

Open in new window

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,

How to resolve this error SFTP error #3 Permission denied mobaxterm to access on redhat VM lucky directory. thanks
error1.jpg
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
0
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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
Hi

My redhat (guest OS) having issue for not able to resolve the hostname like google.com but able to ping 8.8.8.8.

I didn't do anything at all just to ensure that it can ping Google first and my network subnet like 192.168.1.0/24 when my redhat added a NAT Network adapter without issue.

After that I connect my fortinet vpn client thr IPSec and still can ping and resolve my private cloud thr hostname.

Next day I do the same thing like connect to my iPad 4G network to my Hp laptop wifi.

Can ping and resolved on my hp laptop even being connected to vpn.

The guest os redhat from virtualbox on nat can ping 8.8.8.8 but not able to resolve now.

Why yesterday can and today can't without changing anything?

Thanks.
0
Hi

My redhat (guest OS) having issue for not able to resolve the hostname like google.com but able to ping 8.8.8.8.

I didn't do anything at all just to ensure that it can ping Google first and my network subnet like 192.168.1.0/24 when my redhat added a NAT Network adapter without issue.

After that I connect my fortinet vpn client thr IPSec and still can ping and resolve my private cloud thr hostname.

Next day I do the same thing like connect to my iPad 4G network to my Hp laptop wifi.

Can ping and resolved on my hp laptop even being connected to vpn.

The guest os redhat from virtualbox on nat can ping 8.8.8.8 but not able to resolve now.

Why yesterday can and today can't without changing anything?

Thanks.
0
Hi,

I need to transfer the python script to the redhat 7.5 on virtualbox.

i've done the following:-

vb_setting1.jpg
Error

vb_setting2.jpg
Thanks
0
What's the best way to monitor for UDP syslog traffic coming in from a redhat 4 and redhat 5 syslog clients if it's not arriving at the syslog server. The syslog server is running on a Redhat 6 server. netstat -taulpe | grep syslog is showing that UDP is listening on all IP's on the server but I'd like to see if there is any other way apart from running  tcpdump -i <nic> port 514. Would watch lsof -a -i:514 show it?
0
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 …
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.