From 962ca9157497ea11ebe13b2576cb1acf65fb98d9 Mon Sep 17 00:00:00 2001 From: Miroslav Lichvar Date: Mon, 23 May 2016 09:00:42 +0200 Subject: [PATCH] doc: improve answer in FAQ for firewall issue --- doc/faq.adoc | 25 ++++++++++++++++++------- 1 file changed, 18 insertions(+), 7 deletions(-) diff --git a/doc/faq.adoc b/doc/faq.adoc index 08cc31a..de1b922 100644 --- a/doc/faq.adoc +++ b/doc/faq.adoc @@ -205,13 +205,24 @@ following questions. === Behind a firewall? -If there is a firewall between you and the NTP server you're trying to use, the -packets may be blocked. Try using a tool like `wireshark` or `tcpdump` to see if -you're getting responses from the server. If you have an external modem, see -if the receive light blinks straight after the transmit light (when the link is -quiet apart from the NTP traffic). Try adding `log measurements` to the -_chrony.conf_ file and look in the _measurements.log_ file after `chronyd` has -been running for a short period. See if any measurements appear. +Check the `Reach` value printed by the ``chronyc``'s `sources` command. If it's +zero, it means `chronyd` did not get any valid responses from the NTP server +you are trying to use. If there is a firewall between you and the server, the +packets may be blocked. Try using a tool like `wireshark` or `tcpdump` to see +if you're getting any responses from the server. + +When `chronyd` is receiving responses from the servers, the output of the +`sources` command issued few minutes after `chronyd` start might look like +this: + +---- +210 Number of sources = 3 +MS Name/IP address Stratum Poll Reach LastRx Last sample +=============================================================================== +^* foo.example.net 2 6 377 34 +484us[ -157us] +/- 30ms +^- bar.example.net 2 6 377 34 +33ms[ +32ms] +/- 47ms +^+ baz.example.net 3 6 377 35 -1397us[-2033us] +/- 60ms +---- === Are NTP servers specified with the `offline` option?