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Михаил Ребров
Asked: 2020-08-27 11:12:34 +0800 CST

Problem with outgoing connections on Ubuntu 16.04

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We have Ubuntu 16.04.3 running in OpenVZ

At some time from this server mail has ceased to be sent.
And the problem was not with the application that sends mail (on the other machine everything worked correctly).

At the same time, I noticed that the app stopped working with other third party services(REST API's).

I tried to execute: wget __SOME_HOST___
...And nothing happened!
failed: Connection timed out.

All incoming connections are working fine (ssh, nginx, mysql, etc).

I tried to understand what happened and noticed that at this time the config of the network interface changed.

/etc/network/interfaces:

# Auto generated lo interface
auto lo
iface lo inet loopback

# Auto generated venet0 interface
auto venet0
iface venet0 inet manual
        up ifconfig venet0 up
        up ifconfig venet0 127.0.0.2
        up route add default dev venet0
        down route del default dev venet0
        down ifconfig venet0 down


iface venet0 inet6 manual
        up ifconfig venet0 add 2a00:f940:2:1:2::1a7c/65
        down ifconfig venet0 del 2a00:f940:2:1:2::1a7c/65
        up route -A inet6 add default dev venet0
        down route -A inet6 del default dev venet0

auto venet0:0
iface venet0:0 inet static
        address xxx.xx.xxx.xxx
        netmask 255.255.255.255

> ifconfig

OUTPUT:

lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:65536  Metric:1
          RX packets:5934353 errors:0 dropped:0 overruns:0 frame:0
          TX packets:5934353 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:1764429418 (1.7 GB)  TX bytes:1764429418 (1.7 GB)

venet0    Link encap:UNSPEC  HWaddr 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00  
          inet addr:127.0.0.2  P-t-P:127.0.0.2  Bcast:0.0.0.0  Mask:255.255.255.255
          inet6 addr: 2a00:f940:2:1:2::1a7c/65 Scope:Global
          UP BROADCAST POINTOPOINT RUNNING NOARP  MTU:1500  Metric:1
          RX packets:12466713 errors:0 dropped:0 overruns:0 frame:0
          TX packets:23511846 errors:0 dropped:1 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:1305628952 (1.3 GB)  TX bytes:25217918312 (25.2 GB)

venet0:0  Link encap:UNSPEC  HWaddr 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00  
          inet addr:xxx.xx.xxx.xxx  P-t-P:xxx.xx.xxx.xxx  Bcast:xxx.xx.xxx.xxx  Mask:255.255.255.255
          UP BROADCAST POINTOPOINT RUNNING NOARP  MTU:1500  Metric:1

Does anyone have any idea?

UPD

cat /proc/sys/net/ipv4/ip_forward
OUTPUT:
1
networking server

0 Answers