| venet cannot listen on ip address specified [message #53160] |
Wed, 31 January 2018 10:42  |
kdlsw
Messages: 2
Registered: January 2018
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Junior Member |
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I have a VPS Ubuntu running on OpenVZ, I think. The problem I am having is, some program requires user to manually specify an IP address for listening, I do not know which IP address to put with the Venet0 and Venet0:0.
Here is the ifconfig
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:16436 Metric:1
RX packets:155139 errors:0 dropped:0 overruns:0 frame:0
TX packets:155139 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:275037011 (275.0 MB) TX bytes:275037011 (275.0 MB)
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: 2001:3e6:643:0:2:1:0:57/128 Scope:Global
UP BROADCAST POINTOPOINT RUNNING NOARP MTU:1500 Metric:1
RX packets:1826058 errors:0 dropped:0 overruns:0 frame:0
TX packets:1040054 errors:0 dropped:1 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:2360040465 (2.3 GB) TX bytes:120564554 (120.5 MB)
venet0:0 Link encap:UNSPEC HWaddr 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00
inet addr:183.181.101.87 P-t-P:183.181.101.87 Bcast:183.181.101.87 Mask:255.255.255.255
UP BROADCAST POINTOPOINT RUNNING NOARP MTU:1500 Metric:1
I did some experiments with netcat, and the results are really confusing. I first tried the public ip address on venet0:0 listening on port 80 didn't work, no connection received. Then I tried netcat default ip listening which only port parameter required it worked, so, with this command running, I want to find out which address it is listening on, I did
The resultActive Internet connections (servers and established)
Proto Recv-Q Send-Q Local Address Foreign Address State
tcp 0 0 127.0.0.1:8022 0.0.0.0:* LISTEN
tcp 0 0 0.0.0.0:25 0.0.0.0:* LISTEN
tcp 0 0 0.0.0.0:3843 0.0.0.0:* LISTEN
tcp 0 0 0.0.0.0:80 0.0.0.0:* LISTEN
...
tcp6 0 0 :::25 :::* LISTEN
tcp6 0 0 :::3843 :::* LISTEN
It shows netcat is listening on 0.0.0.0, I guess all program without requiring a specific listening address is setting default to 0.0.0.0, and all addresses will be included.
Then I tried to give 0.0.0.0 as a specified address to netcat Something strange happened, in netstat, it shows
Active Internet connections (servers and established)
Proto Recv-Q Send-Q Local Address Foreign Address State
tcp 0 0 127.0.0.1:8022 0.0.0.0:* LISTEN
tcp 0 0 0.0.0.0:25 0.0.0.0:* LISTEN
tcp 0 0 0.0.0.0:3843 0.0.0.0:* LISTEN
tcp 0 0 0.0.0.0:45690 0.0.0.0:* LISTEN
...
tcp6 0 0 :::25 :::* LISTEN
tcp6 0 0 :::3843 :::* LISTEN
Apparently port 80 becomes 45690, and this port is random. I also tested with other programs, this random port changing issue seems not happening. When I tried to connect netcat with my browser via port 45690, it showsinvalid connection to [183.181.101.87] from (UNKNOWN) [101.229.171.186] 31559
If I do connection from a browser gives something similar to GET / HTTP/1.1
Host: 183.181.101.87:45690
Connection: keep-alive
...
I am not sure what happened here, and for other programs, even if the listening port is not randomized, I cannot establish any connection.
Any suggesions? Thank you
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