[Venis33]

Podešavao sam lični uređaj i primetio da se vreme2.dmdm.rs (195.250.114.105) čudno ponaša (deo koji nisam dokumentovao). Kasnije sam proveravao aktivne servere u našem rs.pool.ntp.org i tu sam uočio da ovaj server stalno "ispada" i vraća se:

10.40, vreme2 je prisutno u poolu:

root@lap-xubuntu:~# dig rs.pool.ntp.org

; <<>> DiG 9.18.39-0ubuntu0.24.04.3-Ubuntu <<>> rs.pool.ntp.org
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 52519
;; flags: qr rd ra; QUERY: 1, ANSWER: 4, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 65494
;; QUESTION SECTION:
;rs.pool.ntp.org. IN A

;; ANSWER SECTION:
rs.pool.ntp.org. 18 IN A 217.24.20.5
rs.pool.ntp.org. 18 IN A 147.91.26.20
rs.pool.ntp.org. 18 IN A 195.250.114.105
rs.pool.ntp.org. 18 IN A 195.178.58.245

;; Query time: 1 msec
;; SERVER: 127.0.0.53#53(127.0.0.53) (UDP)
;; WHEN: Wed Apr 08 10:40:01 CEST 2026
;; MSG SIZE rcvd: 108

10.41, vreme2 nije prisutno:

root@lap-xubuntu:~# dig rs.pool.ntp.org


; <<>> DiG 9.18.39-0ubuntu0.24.04.3-Ubuntu <<>> rs.pool.ntp.org
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 39406
;; flags: qr rd ra; QUERY: 1, ANSWER: 3, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 65494
;; QUESTION SECTION:
;rs.pool.ntp.org. IN A

;; ANSWER SECTION:
rs.pool.ntp.org. 52 IN A 217.24.20.5
rs.pool.ntp.org. 52 IN A 195.178.58.245
rs.pool.ntp.org. 52 IN A 147.91.26.20

;; Query time: 0 msec
;; SERVER: 127.0.0.53#53(127.0.0.53) (UDP)
;; WHEN: Wed Apr 08 10:41:27 CEST 2026
;; MSG SIZE rcvd: 92

pool.ntp.org A RRovi bi trebalo maksimalno da vrate četiri zapisa koji se smenjuju a u ispadu ih bude troje, tako da definitivno nešto ne valja. Ovde je olakšavajuća okolnost što naš pool nema više od četiri servera pa je lakše primetiti ovako nešto. Meni liči na neki agresivni firewall u koji bi mogla da udari neka provera zdravlja ntp.org a da nije propuštena što bi moglo da izazove ovakve ispade.

Takođe, ping ponašanje je vrlo interesantno, ruter(?) vrati svaki treći paket, što bi moglo da potvrdi prethodnu teoriju.

Code:

From 77-105-12-34.smin-1.sezampro.rs (77.105.12.34) icmp_seq=3 Packet filtered From 77-105-12-34.smin-1.sezampro.rs (77.105.12.34) icmp_seq=6 Packet filtered From 77-105-12-34.smin-1.sezampro.rs (77.105.12.34) icmp_seq=9 Packet filtered From 77-105-12-34.smin-1.sezampro.rs (77.105.12.34) icmp_seq=12 Packet filtered

Više o: Nacionalni javni stratum 2 NTP serveri

[Venis33]

8. aprila je uspostavljen kontakt i već sutradan nisam primetio ispade; od 9. aprila sve deluje stabilno.

Takođe i ping prolazi od prvog paketa, nije više svaki treći.

Code:

From 77-105-12-34.smin-1.sezampro.rs (77.105.12.34) icmp_seq=1 Packet filtered From 77-105-12-34.smin-1.sezampro.rs (77.105.12.34) icmp_seq=2 Packet filtered From 77-105-12-34.smin-1.sezampro.rs (77.105.12.34) icmp_seq=3 Packet filtered From 77-105-12-34.smin-1.sezampro.rs (77.105.12.34) icmp_seq=4 Packet filtered From 77-105-12-34.smin-1.sezampro.rs (77.105.12.34) icmp_seq=5 Packet filtered From 77-105-12-34.smin-1.sezampro.rs (77.105.12.34) icmp_seq=6 Packet filtered From 77-105-12-34.smin-1.sezampro.rs (77.105.12.34) icmp_seq=7 Packet filtered From 77-105-12-34.smin-1.sezampro.rs (77.105.12.34) icmp_seq=8 Packet filtered From 77-105-12-34.smin-1.sezampro.rs (77.105.12.34) icmp_seq=9 Packet filtered From 77-105-12-34.smin-1.sezampro.rs (77.105.12.34) icmp_seq=10 Packet filtered From 77-105-12-34.smin-1.sezampro.rs (77.105.12.34) icmp_seq=11 Packet filtered From 77-105-12-34.smin-1.sezampro.rs (77.105.12.34) icmp_seq=12 Packet filtered