Troubleshooting

Windows:

ping -v is now deprecated which was useful for sending ICMP with TOS field values. Try ping -Q as alternative from a UNIX machine.

Unix:

ping –Q

-Q tos Set Quality of Service -related bits in ICMP datagrams.  tos can be

either decimal or hex number.  Traditionally (RFC1349), these  have

been  interpreted  as: 0 for reserved (currently being redefined as

congestion control), 1-4 for Type of Service  and  5-7  for  Prece-

dence.   Possible  settings  for Type of Service are: minimal cost:

0x02, reliability: 0x04, throughput: 0x08, low delay: 0x10.  Multi-

ple  TOS  bits should not be set simultaneously.  Possible settings

for special Precedence range from priority (0x20)  to  net  control

(0xe0).   You must be root (CAP_NET_ADMIN capability) to use Criti-

cal or higher precedence value.  You cannot set bit 0x01 (reserved)

unless  ECN  has  been  enabled  in  the kernel.  In RFC2474, these

fields has been redefined as 8-bit  Differentiated  Services  (DS),

consisting  of: bits 0-1 of separate data (ECN will be used, here),

and bits 2-7 of Differentiated Services Codepoint (DSCP).

Man curl or curl –help

Curl can be useful to check TCP connections for http or https.

Result could be Connection Timeout, Connection Refused or Connected (200 OK).

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