Network dropping, Centos freezes, reboot to restore, repeat

Issues related to applications and software problems and general support
mjz
Posts: 66
Joined: 2020/02/13 22:05:02

Network dropping, Centos freezes, reboot to restore, repeat

Post by mjz » 2020/02/20 23:09:08

I am new to Centos.

It has been working fine for about a week, but today I noticed I can't maintain an FTP connection for more than a few minutes when the network freezes, drops, and Centos then freezes and I have to do a manual reset. Each time, I get a new IP address (DHCP) assigned. This has never happened before. My router maintains the mac address's and always reassigns the same IP address, but not anymore with this issue.

Would someone point me to the logs I can check to see what is going on? I may have a hardware problem (network card)? It boots up fine, runs normally for 10 minutes or so then hangs.

(I work with the system using SSH on a remote machine. When the hang occurs, I go to the computer room and connect a monitor to the VGA port and it's blank - keyboard/mouse no response forcing a reset. Upon resetting, monitor comes up as normal.)

User avatar
TrevorH
Forum Moderator
Posts: 29985
Joined: 2009/09/24 10:40:56
Location: Brighton, UK

Re: Network dropping, Centos freezes, reboot to restore, repeat

Post by TrevorH » 2020/02/21 01:15:06

What's the output from lspci -nn | grep -i net ?
CentOS 6 died in November 2020 - migrate to a new version!
Info for USB installs on http://wiki.centos.org/HowTos/InstallFromUSBkey
CentOS 5 is dead, do not use it.
Full time Geek, part time moderator. Use the FAQ Luke

mjz
Posts: 66
Joined: 2020/02/13 22:05:02

Re: Network dropping, Centos freezes, reboot to restore, repeat

Post by mjz » 2020/02/21 16:17:35

05:00.0 Ethernet controller [0200]: Intel Corporation 80003ES2LAN Gigabit Ethernet Controller (Copper) [8086:1096] (rev 01)
05:00.1 Ethernet controller [0200]: Intel Corporation 80003ES2LAN Gigabit Ethernet Controller (Copper) [8086:1096] (rev 01)

mjz
Posts: 66
Joined: 2020/02/13 22:05:02

Re: Network dropping, Centos freezes, reboot to restore, repeat

Post by mjz » 2020/02/21 16:29:09

I did a test between two identical computers on the same lan running the same OS (Centos 8) (192.168.1.146 & 192.168.1.148) and ftp transfer for large files worked perfectly .. no network disconnect or needing to reboot. I don't think there is anything wrong with hardware - I suspect firewall, but I am still puzzled since the other machine is on the same lan, BUT is a windows 10 box with a USB connected drive where the large files are located. Transferring them to the server is where I have issues.

summitflier
Posts: 13
Joined: 2020/01/22 22:16:05

Re: Network dropping, Centos freezes, reboot to restore, repeat

Post by summitflier » 2020/02/21 17:25:08

what is output from netstat -i ?

lightman47
Posts: 1225
Joined: 2014/05/21 20:16:00
Location: Central New York, USA

Re: Network dropping, Centos freezes, reboot to restore, repeat

Post by lightman47 » 2020/02/21 20:45:58

Any chance there is a "second" DHCP server on your network? Example: I 'used the back end' of a Linksys router as a switch - but forgot to disable the DHCP on it (already had a server running DHCP with reserved addresses) with similar dropout results. What about a static machine address on a DHCP network - might work ... for a while.

Just a thought of likely little relevance.
Remember - importing/building packages will likely "byte you in the butt" come update time, long after you'd forgotten you did that! Use repos whenever possible.

mjz
Posts: 66
Joined: 2020/02/13 22:05:02

Re: Network dropping, Centos freezes, reboot to restore, repeat

Post by mjz » 2020/02/21 22:17:33

I thought about that - and no, there is no other DHCP server, just the one.
But I did set static address and seems to work. The system is stable now. Filezilla is staying up as well.

I won't call it "solved" until I try again with the windows machine. Right now between Centos machines, file serving is very fast (100 Mb/s)

lightman47
Posts: 1225
Joined: 2014/05/21 20:16:00
Location: Central New York, USA

Re: Network dropping, Centos freezes, reboot to restore, repeat

Post by lightman47 » 2020/02/21 22:28:17

Perhaps another machine is intermittently "getting" your static address (boots up/lease runs out first). This can be avoided with reserved/assigned addresses on the DHCP server - then all machines can be DHCP, and certain chosen addresses can be 'predictable'. It's exceptionally simple to do.

;-)
Remember - importing/building packages will likely "byte you in the butt" come update time, long after you'd forgotten you did that! Use repos whenever possible.

MartinR
Posts: 622
Joined: 2015/05/11 07:53:27
Location: UK

Re: Network dropping, Centos freezes, reboot to restore, repeat

Post by MartinR » 2020/02/22 15:27:54

Just going back to your initial report for a moment:
  1. It has been working fine for about a week, but today I noticed I can't maintain an FTP connection for more than a few minutes when the network freezes, drops, and Centos then freezes and I have to do a manual reset.
  2. Each time, I get a new IP address (DHCP) assigned. This has never happened before. My router maintains the mac address's and always reassigns the same IP address, but not anymore with this issue.
  3. Would someone point me to the logs I can check to see what is going on?
  4. I may have a hardware problem (network card)?
  5. It boots up fine, runs normally for 10 minutes or so then hangs.
  6. I work with the system using SSH on a remote machine
  7. When the hang occurs, I go to the computer room and connect a monitor to the VGA port and it's blank - keyboard/mouse no response forcing a reset.
  8. Upon resetting, monitor comes up as normal.
I wonder if your analysis is correct. Are you certain that "the network freezes, drops, and Centos then freezes"[1]? Could it be CentOS freezing, and then the network failing? Statement [7] is possibly the key. The system being unresponsive and needing a reset (I'm assuming you mean reboot) could be the cause, not the symptom. Likewise [5] looks very hardware related.

I had something similar some years ago on a tower system and found I needed to keep the window open in winter and put a fan against the ventilation slots in order to run for more than a few minutes. Eventually the failing PSU finally went, was replaced, and the machine functioned perfectly.

Of course I may be barking up the wrong tree entirely, it wouldn't be the first time, but I would want to ensure the underlying system worked before examining higher layers.

mjz
Posts: 66
Joined: 2020/02/13 22:05:02

Re: Network dropping, Centos freezes, reboot to restore, repeat

Post by mjz » 2020/02/22 17:55:31

It's running fine now, but only if I ftp between other unix machines. If I try to maintain a connection to a win 10 computer, I get the problem again. Something in win10 doesn't like maintaining a connection. Since all machines are on the same LAN served by the same DHCP server, firewall should not be an issue. There is no local firewall only the router has firewall protection.

Post Reply

Return to “CentOS 8 - General Support”