Verify the GRE/UDP tunnel between vSCOUT and vSTREAM

Introduction

vSCOUT does not produce session detail records nor does it store packets . However, you can still gain access to session details and packet-level data by configuring traffic forwarding from vSCOUT to vSTREAM or InfiniStream interface managed by the same nGeniusONE server. Forwarded packets can be stripped out of the tunnel and made availabe for packet-level analysis on the receiving interface.  

This procedure allows you to verify is the tunnel is operational i.e. packets are being transported between vSCOUT and vSTREAM.

 

Solution

This procedure assumes vSCOUT/vSTREAM has been installed and configured correctly by COMCERT engineers and has worked correcly.

On vSTREAM:

Login to vSTREAM CLI (ssh) as root

First we need to identify the interface terminating the GRE or UDP tunnel 

Execute the command:

# cat /opt/NetScout/rtm/bin/monitor_ip.conf

Should output:

[root@CRT-VIR-A-VSTREAM6 ~]# cat /opt/NetScout/rtm/bin/monitor_ip.conf
eth1:10.165.30.185

In this example, we want to test the tunnel between the vSCOUT running on host <IP-VSCOUT> and the vSTREAM whlle the tunnel is terminating on interface <INT>.

There is only traffic from vSCOUT towards vSTREAM.  To visulalize this traffic, execute the command:

# tcpdump -i <INT> src host <IP-VSCOUT>

Example (vSCOUT is running on host IP 10.165.30.146):

# tcpdump -i eth1 -n host 10.165.30.146

Should output (omit all warnings):

[root@CRT-VIR-A-VSTREAM6 ~]# tcpdump -i eth1 -n host 10.165.30.146
tcpdump: /lib64/libcrypto.so.10: no version information available (required by tcpdump)
tcpdump: WARNING: eth1: no IPv4 address assigned
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on eth1, link-type EN10MB (Ethernet), capture size 65535 bytes
07:37:05.878177 IP 10.165.30.146 > 10.165.30.185: GREv0, length 1435: gre-proto-0x4e54
07:37:05.878196 IP 10.165.30.146 > 10.165.30.185: GREv0, length 1435: gre-proto-0x4e54
07:37:05.878207 IP 10.165.30.146 > 10.165.30.185: GREv0, length 1435: gre-proto-0x4e54
07:37:05.878221 IP 10.165.30.146 > 10.165.30.185: GREv0, length 1435: gre-proto-0x4e54
07:37:05.878236 IP 10.165.30.146 > 10.165.30.185: GREv0, length 1435: gre-proto-0x4e54
07:37:06.010301 IP 10.165.30.146 > 10.165.30.185: GREv0, length 1423: gre-proto-0x4e54
07:37:06.010320 IP 10.165.30.146 > 10.165.30.185: GREv0, length 1423: gre-proto-0x4e54
07:37:06.010336 IP 10.165.30.146 > 10.165.30.185: GREv0, length 1423: gre-proto-0x4e54
07:37:06.010350 IP 10.165.30.146 > 10.165.30.185: GREv0, length 1423: gre-proto-0x4e54
07:37:06.010365 IP 10.165.30.146 > 10.165.30.185: GREv0, length 1423: gre-proto-0x4e54
07:37:06.376144 IP 10.165.30.146 > 10.165.30.185: GREv0, length 1401: gre-proto-0x4e54
07:37:06.376167 IP 10.165.30.146 > 10.165.30.185: GREv0, length 1401: gre-proto-0x4e54
07:37:06.376177 IP 10.165.30.146 > 10.165.30.185: GREv0, length 1401: gre-proto-0x4e54
07:37:06.376194 IP 10.165.30.146 > 10.165.30.185: GREv0, length 1401: gre-proto-0x4e54
07:37:06.376204 IP 10.165.30.146 > 10.165.30.185: GREv0, length 1401: gre-proto-0x4e54
07:37:06.951974 IP 10.165.30.146 > 10.165.30.185: GREv0, length 1425: gre-proto-0x4e54
07:37:06.953081 IP 10.165.30.146 > 10.165.30.185: GREv0, length 1425: gre-proto-0x4e54
07:37:06.953093 IP 10.165.30.146 > 10.165.30.185: GREv0, length 1425: gre-proto-0x4e54
07:37:06.953123 IP 10.165.30.146 > 10.165.30.185: GREv0, length 1425: gre-proto-0x4e54
07:37:06.953132 IP 10.165.30.146 > 10.165.30.185: GREv0, length 1425: gre-proto-0x4e54

Note that you will only see GRE or UDP traffic when there is activity on the host running vSCOUT.