ntpd, ntpdate, rdate

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궁금해서 확인해봤습니다.

* DNS 리졸빙내역
time.bora.net (203.248.240.140)
time.ewha.net (114.207.245.166)

* ntpdate time.ewha.net  실행시 캡쳐한 패킷 -> 123번 포트 사용
16:07:51.615309 IP 10.0.0.2.ntp > 114.207.245.166.ntp: NTPv4, Client, length 48
16:07:51.620379 IP 114.207.245.166.ntp > 10.0.0.2.ntp: NTPv4, Server, length 48
16:07:51.620429 IP 10.0.0.2.ntp > 114.207.245.166.ntp: NTPv4, Client, length 48
16:07:51.625493 IP 114.207.245.166.ntp > 10.0.0.2.ntp: NTPv4, Server, length 48
16:07:51.625532 IP 10.0.0.2.ntp > 114.207.245.166.ntp: NTPv4, Client, length 48
16:07:51.630399 IP 114.207.245.166.ntp > 10.0.0.2.ntp: NTPv4, Server, length 48
16:07:51.630435 IP 10.0.0.2.ntp > 114.207.245.166.ntp: NTPv4, Client, length 48
16:07:51.635405 IP 114.207.245.166.ntp > 10.0.0.2.ntp: NTPv4, Server, length 48

* rdate -s time.bora.net   실행시 캡쳐한 패킷 -> 37번 포트 사용
16:06:43.357404 IP 10.0.0.2.46607 > time.bora.net.time: Flags [S], seq 2642715429, win 65535, options [mss 1460,nop,wscale 6,sac
16:06:43.361895 IP time.bora.net.time > 10.0.0.2.46607: Flags [S.], seq 1200549318, ack 2642715430, win 49248, options [nop,nop,
16:06:43.361917 IP 10.0.0.2.46607 > time.bora.net.time: Flags [.], ack 1, win 1026, options [nop,nop,TS val 2586383464 ecr 34170
16:06:43.366456 IP time.bora.net.time > 10.0.0.2.46607: Flags [P.], seq 1:5, ack 1, win 49248, options [nop,nop,TS val 341704755
16:06:43.366466 IP time.bora.net.time > 10.0.0.2.46607: Flags [F.], seq 5, ack 1, win 49248, options [nop,nop,TS val 3417047555 
16:06:43.366479 IP 10.0.0.2.46607 > time.bora.net.time: Flags [.], ack 6, win 1025, options [nop,nop,TS val 2586383476 ecr 34170
16:06:43.366504 IP 10.0.0.2.46607 > time.bora.net.time: Flags [F.], seq 1, ack 6, win 1026, options [nop,nop,TS val 2586383476 e
16:06:43.004294 IP time.bora.net.time > 10.0.0.2.46607: Flags [.], ack 2, win 49248, options [nop,nop,TS val 3417047555 ecr 2586

[ ~ # ] egrep "time|ntp" /etc/services 
time 37/tcp   timserver
time 37/udp   timserver
ntp 123/tcp   #Network Time Protocol
ntp 123/udp   #Network Time Protocol


vmware는 가상머신에서 시간이 이상하게 빨리가는 문제가 있더군요.

rc.conf에 ntpd_enable="YES" 세팅했는데 대몬이 안떠있길래 보니 1000초이상 차이나면 대몬이 안뜨네요.

대몬 띄워놓으면 왠지 든든하긴 하지만 또 죽을까봐 보다 확실한방법으로 일단 이렇게 크론탭에 걸어놨습니다.

1  *   *   *   *   root    /usr/sbin/ntpdate time.ewha.net  > /dev/null 2>&1
REDHAT °è¿­ ±âÁØÀ¸·Î º¸¸é...

==============================================================
1. /etc/ntp.conf ¿¡
tinker panic À» 0 À¸·Î ¼³Á¤ÇØ ÁÖ°í

2. /etc/ntp/step-tickers ¿¡ ÃÖÃÊ ±âµ¿½Ã ½ÌÅ©ÇÒ NTP ¼­¹ö¸¦ ÁöÁ¤ÇÑ´Ù.
==============================================================

ÀÌÁ¤µµ¸é, tick ÀÌ ºñ Á¤»óÀûÀ϶§µµ NTP ¼­ºñ½º ÀÚü°¡ Á״´ٴø°¡, VM ¾ÈÂÊ¿¡¼­
ºñ Á¤»óÀûÀÎ tick À» ¾ò´Â Çö»óÀ» "¼­ºñ½º °¡´ÉÇÑ ¼öÁØ" À¸·Î ÁÙÀÏ ¼ö ÀÖ½À´Ï´Ù.

 * http://kb.vmware.com/kb/1006427


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