server latency

[Walt E]

Hello,

When I want to know the approximate latency from local to remote servers, I know I can use icmp ping.
However, some servers, such as by Azure's default security policy, prohibit icmp ping.
So, in this situation, how do I know the local latency to those servers?

Thanks.

[Michael Kjörling]

Post by Walt E
When I want to know the approximate latency from local to remote servers, I know I can use icmp ping.
However, some servers, such as by Azure's default security policy, prohibit icmp ping.
So, in this situation, how do I know the local latency to those servers?

nmap -sn is likely to be a good starting point.

If you know a port that is open, then you can try

nmap -sS/-sU -p port host

where -sS selects a TCP SYN scan and -sU selects a UDP scan, -p
specifies the port, and host is what it says on the tin.

For example, a typical host would probably give reasonable results
for:

$ nmap -sS -p 22,3389 192.0.2.1

That will check the default SSH and Microsoft RDP ports on 192.0.2.1.

[Andy Smith]

Hi,

Post by Walt E
However, some servers, such as by Azure's default security policy, prohibit icmp ping.
So, in this situation, how do I know the local latency to those servers?

I pick a port that I know is open and use a traceroute that uses
those kinds of UDP/TCP packets instead of ICMP.

Also mtr is quite interesting to provide intermediary hop details
and other useful stuff. Just normal traceroute can be made to do
UDP/TCP though.

Example: http://paste.debian.net/plain/1324660

Thanks,
Andy