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hinatahajime9801
Copper Contributor
Dec 21, 2021

Started netserver on remote machine, but netperf cannot make connection

I'm using two azure machines to run a TCP_STREAM test from netperf between them.

The remote machine is called `mymachine-Standard-D8as-v4-premium-disk-west` and the local one is called `mymachine-Standard-D8as-v4-premium-disk`.

I follow these steps:

  1. Start the netserver in the remote server at port 2333:
ubuntu@mymachine-Standard-D8as-v4-premium-disk-west-0001:~$ sudo netserver -p 2333
Starting netserver with host 'IN(6)ADDR_ANY' port '2333' and family AF_UNSPEC

make sure it is started:

ubuntu@mymachine-Standard-D8as-v4-premium-disk-west-0001:~$ ps -ef | grep netserver
root        4139       1  0 16:16 ?        00:00:00 /usr/bin/netserver
root       26990       1  0 16:21 ?        00:00:00 netserver -p 2333
ubuntu     27011    1906  0 16:25 pts/0    00:00:00 grep --color=auto netserver

ubuntu@mymachine-Standard-D8as-v4-premium-disk-west-0001:~$sudo lsof -i tcp:2333
COMMAND     PID USER   FD   TYPE DEVICE SIZE/OFF NODE NAME
netserver 26990 root    3u  IPv6  66361      0t0  TCP *:2333 (LISTEN)
  1. Get the IP address of the remote machine:
ubuntu@mymachine-Standard-D8as-v4-premium-disk-west-0001:~$ ifconfig
enP17061s1: flags=6211<UP,BROADCAST,RUNNING,SLAVE,MULTICAST>  mtu 1500
      ether 00:22:48:79:d8:1b  txqueuelen 1000  (Ethernet)
      RX packets 80523  bytes 114044067 (114.0 MB)
      RX errors 0  dropped 0  overruns 0  frame 0
      TX packets 12984  bytes 1550954 (1.5 MB)
      TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
      inet 10.2.0.27  netmask 255.255.192.0  broadcast 10.2.63.255
      inet6 fe80::222:48ff:fe79:d81b  prefixlen 64  scopeid 0x20<link>
      ether 00:22:48:79:d8:1b  txqueuelen 1000  (Ethernet)
      RX packets 29439  bytes 130068468 (130.0 MB)
      RX errors 0  dropped 0  overruns 0  frame 0
      TX packets 12987  bytes 1555721 (1.5 MB)
      TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

lo: flags=73<UP,LOOPBACK,RUNNING>  mtu 65536
      inet 127.0.0.1  netmask 255.0.0.0
      inet6 ::1  prefixlen 128  scopeid 0x10<host>
      loop  txqueuelen 1000  (Local Loopback)
      RX packets 222  bytes 30160 (30.1 KB)
      RX errors 0  dropped 0  overruns 0  frame 0
      TX packets 222  bytes 30160 (30.1 KB)
      TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

Which shows the IP address for the west machine is 10.2.0.27!

  1. Run netperf from the local machine
netperf -H 10.2.0.27 -p 2333 -D 0.5 -c -C -l 20 -t TCP_STREAM -P 0 -f g -- -b 2 -D -o throughput,throughput_units

and now it gives me:

establish control: are you sure there is a netserver listening on 10.2.0.27 at port 2333?
establish_control could not establish the control connection from 0.0.0.0 port 0 address family AF_UNSPEC to 10.2.0.27 port 2333 address family AF_INET

This is so confusing! Because I have verified that the netserver is listening on 10.2.0.27 at port 2333. Actually, the same procedure works fine on GCE's machines.

I wonder what may cause this and how to fix it.

 

I also looked at the `ip route`, `ufw status`, `sudo traceroute the-other-system` on both machines.

On the west machine:

ubuntu@mymachine-Standard-D8as-v4-premium-disk-west-0001:~$ ip route
default via 10.2.0.1 dev eth0 proto dhcp src 10.2.0.27 metric 100 
10.2.0.0/18 dev eth0 proto kernel scope link src 10.2.0.27 
168.63.129.16 via 10.2.0.1 dev eth0 proto dhcp src 10.2.0.27 metric 100 
169.254.169.254 via 10.2.0.1 dev eth0 proto dhcp src 10.2.0.27 metric 100 
ubuntu@mymachine-Standard-D8as-v4-premium-disk-west-0001:~$ ufw status
ERROR: You need to be root to run this script
ubuntu@mymachine-Standard-D8as-v4-premium-disk-west-0001:~$ sudo traceroute 10.1.0.62
traceroute to 10.1.0.62 (10.1.0.62), 30 hops max, 60 byte packets
 1  * * *
...
30  * * *

On the local machine:

ubuntu@jane-cr22-Standard-D8as-v4-premium-disk-0001:~$ ip route
default via 10.1.0.1 dev eth0 proto dhcp src 10.1.0.62 metric 100 
10.1.0.0/18 dev eth0 proto kernel scope link src 10.1.0.62 
168.63.129.16 via 10.1.0.1 dev eth0 proto dhcp src 10.1.0.62 metric 100 
169.254.169.254 via 10.1.0.1 dev eth0 proto dhcp src 10.1.0.62 metric 100 
ubuntu@mymachine-Standard-D8as-v4-premium-disk-0001:~$ ufw status
ERROR: You need to be root to run this script
ubuntu@mymachine-Standard-D8as-v4-premium-disk-0001:~$ sudo ufw status
Status: inactive
ubuntu@mymachine-Standard-D8as-v4-premium-disk-0001:~$ sudo traceroute  10.2.0.27
traceroute to 10.2.0.27 (10.2.0.27), 30 hops max, 60 byte packets
 1  * * *
...
30  * * *

Besides, for the west machine, I've added an inbound port rule that has priority 100, allowing any source and destination, with port range 2333. But still, the local machine cannot connect with the remote one.

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