ping reports "system error"

Kernels & Hardware, configuring network, installing services

ping reports "system error"

Postby hbauer » 2019-01-26 16:48

Hi to all

today I installed a Debian system with debootstrap. (this page is in german but I am sure you get the steps https://www.hagen-bauer.de/2019/01/alix ... retch.html) The system is running and allows me to login and install software. So in general it looks successful. Unfortunately there is something wrong with DNS.

I can ping other hosts using the ip address but if I try to ping them via fqdn it get an "system error"

Any hint where I could start?

Code: Select all
nslookup host.domain.lcl
Server:      192.168.2.1
Address:   192.168.2.1#53

Name:   host.domain.lcl
Address: 192.168.2.16

root@host:~# ping 192.168.2.16
PING 192.168.2.16 (192.168.2.16) 56(84) bytes of data.
64 bytes from 192.168.2.16: icmp_seq=1 ttl=64 time=0.089 ms
64 bytes from 192.168.2.16: icmp_seq=2 ttl=64 time=0.081 ms
^C
--- 192.168.2.16 ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 1005ms
rtt min/avg/max/mdev = 0.081/0.085/0.089/0.004 ms
root@host:~# ping host.domain.lcl
ping: host.domain.lcl: System error
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Re: ping reports "system error"

Postby Head_on_a_Stick » 2019-01-26 18:15

hbauer wrote:Any hint where I could start?

Enter the error message into your favorite search engine and follow the bread crumbs.

If you still can't figure it out, post back listing everything you have tried in as much detail as possible so we don't waste your time suggesting things you have already attempted.
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Re: ping reports "system error"

Postby hbauer » 2019-01-26 20:20

Thats what I already did but with https://www.google.com/search?client=fi ... %22+debian I could not find any hint that would match my situation.

I have a plain vanilla Debian system and no Redhat, Windows SMB or NFS problems.

Regards

Hagen
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Re: ping reports "system error"

Postby Head_on_a_Stick » 2019-01-26 21:26

hbauer wrote:Thats what I already did but with https://www.google.com/search?client=fi ... %22+debian I could not find any hint that would match my situation.

Have you checked /etc/nsswitch.conf for any references to "wins"? (As suggested by the first link in your search.)
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Re: ping reports "system error"

Postby hbauer » 2019-01-27 04:34

sure. As I said, I have no Samba installed and the that file is like on my working machine

Code: Select all
hosts:          files myhostname mdns4_minimal [NOTFOUND=return] dns
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Re: ping reports "system error"

Postby p.H » 2019-01-27 11:24

What's "myhostname" doing in the hosts: line ?

Edit : I first thought that it was a placeholder for the actual local host name, but there is really a NSS resolver library with this name...
Is the package libnss-myhostname installed ?
Did you try and move or remove each component in the line in turns and check what happens ?

When I have no clue, I run the command with strace to print system calls.
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Re: ping reports "system error"

Postby hbauer » 2019-01-27 13:55

p.H wrote:Is the package libnss-myhostname installed ?
Did you try and move or remove each component in the line in turns and check what happens ?


I moved back to the original entry of nsswitch.conf which was
Code: Select all
hosts:          files dns

This is the same entry that is working on other boxes I am running so it should be good.

This is the first time I am working with strace and I might overlook important elements. But when I compare the output of strace on a working machine with my problematic box I see this
Code: Select all
open("/etc/nsswitch.conf", O_RDONLY|O_CLOEXEC) = -1 EACCES (Permission denied)
open("/etc/host.conf", O_RDONLY|O_CLOEXEC) = -1 EACCES (Permission denied)
getpid()                                = 477
open("/etc/resolv.conf", O_RDONLY|O_CLOEXEC) = -1 EACCES (Permission denied)

if ping is not able to read this 3 files I can imagine that things might not work. But on my filesystem the ACL looks good.
Code: Select all
ls -ls /etc/nsswitch.conf
4 -rw-r--r-- 1 root root 532 Jan 27 14:59 /etc/nsswitch.conf

ls -ls /etc/resolv.conf
4 -rw-r--r-- 1 root root 63 Jan 27 14:40 /etc/resolv.conf

ls -ls /etc/host.conf
4 -rw-r--r-- 1 root root 9 Aug  7  2006 /etc/host.conf


Why should this ping process not be able to access this files?

Regards
Hagen
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Re: ping reports "system error"

Postby p.H » 2019-01-27 15:05

I don't have a clue. Anyway if ping is executed as root, it should skip file permissions.

Are other programs affected too ?
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Re: ping reports "system error"

Postby hbauer » 2019-01-27 15:13

p.H wrote:Are other programs affected too ?


I cant say. I want to use this machine as icinga host and when ping is not working that does not make sense.

But there are no other obvious errors
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Re: ping reports "system error"

Postby p.H » 2019-01-27 15:24

Can't you test a couple of commands such as wget, traceroute, telnet, nc, ssh... ?
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Re: ping reports "system error"

Postby hbauer » 2019-01-27 15:54

apt install, traceroute, ssh, wget, nslookup, curl are all working
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Re: ping reports "system error"

Postby Head_on_a_Stick » 2019-01-27 16:17

Is there a firewall on host.domain.lcl?
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Re: ping reports "system error"

Postby p.H » 2019-01-27 16:46

AFAIK, a firewall would not deny access to local files and block DNS queries from the local resolver library but allow those from nslookup.
Maybe SELinux or Apparmor ?
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Re: ping reports "system error"

Postby hbauer » 2019-01-27 17:08

ping does also not work with local servers. And I can ping if I use the ip address. only pings via fqdn dont work. . Other hosts on the network can ping via fqdn.

I have not installed apparmor or selinux knowingly.
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Re: ping reports "system error"

Postby bw123 » 2019-01-27 17:38

hbauer wrote: The system is running and allows me to login and install software.
...
Any hint where I could start?


You should start by checking the software you installed after using the guide. Or checking and undoing system changes you made. Nobody on here will know, you have access to the logs and you're the one that made the changes.

Breaking a system tool and then asking what broke it isn't really a good way to go about solving it. Post a lot of info, after you check it first, of course.
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