New answers tagged ping
Answering your update: I don't know anything about HFT trading, but I can practically guarantee that it doesn't take place over ICMP (the protocol used for pinging). Since ICMP messages are likely to be buffered and prioritized differently than traffic carrying your actual data (most likely using TCP or UDP), the ping results are not directly relevant to ...
According to ping man pages, the f flag is: -f: Flood ping. For every ECHO_REQUEST sent a period ''.'' is printed, while for ever ECHO_REPLY received a backspace is printed. This provides a rapid display of how many packets are being dropped. If interval is not given, it sets interval to zero and outputs packets as fast as they come back or one hundred ...
Complementing the previous answer, try to add a rule that allow traffic UDP like the previous answer, and TCP connection like this: # iptables -A INPUT -p tcp --sport 53 -j ACCEPT TCP connection is used when the response data size exceeds 512 bytes, that is normal.
I don't see a rule to allow UDP port 53. Without UDP port 53, you don't get DNS, so it's not surprising that name resolution fails. You need to add a rule to allow incoming UDP traffic from port 53, at least from the DNS server(s) of your Internet access providers. Something like iptables -A INPUT -p udp --sport 53 -j ACCEPT possibly with additional ...
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