Zamanlayıcı sütununda iki alan vardır (yukarıdaki o / p'den):
keepalive (6176.47/0/0)
<1st field> <2nd field>
1st field
Değerlere sahip olabilir:
keepalive
- canlı tutma zamanlayıcı soketi için AÇIK olduğunda
on
- yeniden iletim zamanlayıcısı soketi için AÇIK olduğunda
off
- yukarıdakilerden hiçbiri AÇIK
2nd field
ÜÇ alt alanlara sahiptir:
(6176.47/0/0) -> (a/b/c)
a
= zamanlayıcı değeri (a = 1. alan = "saklayıcı" olduğunda zamanlayıcı zamanlayıcı; a = 1. alan = "açık" olduğunda yeniden iletim zamanlayıcısı)
b
= meydana gelen yeniden iletim
c
sayısı = gönderilen saklayıcı prob sayısı
Örneğin, bir istemci ve bir sunucu (geri döngü değil) arasında açık iki soket vardı. Kalıcı ayar:
KEEPALIVE_IDLETIME 30
KEEPALIVE_NUMPROBES 4
KEEPALIVE_INTVL 10
Ve istemci makine bir kapatma yaptım, bu yüzden sunucu tarafında bir netstat koştu ve çıktı:
Port1:
netstat -c --timer | grep "192.0.0.1:43245 192.0.68.1:49742"
tcp 0 0 192.0.0.1:43245 192.0.68.1:49742 ESTABLISHED keepalive (1.92/0/0)
tcp 0 0 192.0.0.1:43245 192.0.68.1:49742 ESTABLISHED keepalive (0.71/0/0)
tcp 0 0 192.0.0.1:43245 192.0.68.1:49742 ESTABLISHED keepalive (9.46/0/1)
tcp 0 0 192.0.0.1:43245 192.0.68.1:49742 ESTABLISHED keepalive (8.30/0/1)
tcp 0 0 192.0.0.1:43245 192.0.68.1:49742 ESTABLISHED keepalive (7.14/0/1)
tcp 0 0 192.0.0.1:43245 192.0.68.1:49742 ESTABLISHED keepalive (5.98/0/1)
tcp 0 0 192.0.0.1:43245 192.0.68.1:49742 ESTABLISHED keepalive (4.82/0/1)
tcp 0 0 192.0.0.1:43245 192.0.68.1:49742 ESTABLISHED keepalive (3.66/0/1)
tcp 0 0 192.0.0.1:43245 192.0.68.1:49742 ESTABLISHED keepalive (2.50/0/1)
tcp 0 0 192.0.0.1:43245 192.0.68.1:49742 ESTABLISHED keepalive (1.33/0/1)
tcp 0 0 192.0.0.1:43245 192.0.68.1:49742 ESTABLISHED keepalive (0.17/0/1)
tcp 0 0 192.0.0.1:43245 192.0.68.1:49742 ESTABLISHED keepalive (9.01/0/2)
tcp 0 0 192.0.0.1:43245 192.0.68.1:49742 ESTABLISHED keepalive (7.75/0/2)
tcp 0 0 192.0.0.1:43245 192.0.68.1:49742 ESTABLISHED keepalive (6.47/0/2)
tcp 0 0 192.0.0.1:43245 192.0.68.1:49742 ESTABLISHED keepalive (5.29/0/2)
tcp 0 0 192.0.0.1:43245 192.0.68.1:49742 ESTABLISHED keepalive (4.08/0/2)
tcp 0 0 192.0.0.1:43245 192.0.68.1:49742 ESTABLISHED keepalive (2.89/0/2)
tcp 0 0 192.0.0.1:43245 192.0.68.1:49742 ESTABLISHED keepalive (1.73/0/2)
tcp 0 0 192.0.0.1:43245 192.0.68.1:49742 ESTABLISHED keepalive (0.54/0/2)
tcp 0 0 192.0.0.1:43245 192.0.68.1:49742 ESTABLISHED keepalive (9.38/0/3)
tcp 0 0 192.0.0.1:43245 192.0.68.1:49742 ESTABLISHED keepalive (8.23/0/3)
tcp 0 0 192.0.0.1:43245 192.0.68.1:49742 ESTABLISHED keepalive (7.08/0/3)
tcp 0 0 192.0.0.1:43245 192.0.68.1:49742 ESTABLISHED keepalive (5.93/0/3)
tcp 0 0 192.0.0.1:43245 192.0.68.1:49742 ESTABLISHED keepalive (4.76/0/3)
tcp 0 0 192.0.0.1:43245 192.0.68.1:49742 ESTABLISHED keepalive (3.62/0/3)
tcp 0 0 192.0.0.1:43245 192.0.68.1:49742 ESTABLISHED keepalive (2.48/0/3)
tcp 0 0 192.0.0.1:43245 192.0.68.1:49742 ESTABLISHED keepalive (1.32/0/3)
tcp 0 0 192.0.0.1:43245 192.0.68.1:49742 ESTABLISHED keepalive (0.13/0/3)
tcp 0 0 192.0.0.1:43245 192.0.68.1:49742 ESTABLISHED keepalive (8.98/0/4)
tcp 0 0 192.0.0.1:43245 192.0.68.1:49742 ESTABLISHED keepalive (7.78/0/4)
tcp 0 0 192.0.0.1:43245 192.0.68.1:49742 ESTABLISHED keepalive (6.62/0/4)
tcp 0 0 192.0.0.1:43245 192.0.68.1:49742 ESTABLISHED keepalive (5.45/0/4)
tcp 0 0 192.0.0.1:43245 192.0.68.1:49742 ESTABLISHED keepalive (4.29/0/4)
tcp 0 0 192.0.0.1:43245 192.0.68.1:49742 ESTABLISHED keepalive (3.14/0/4)
tcp 0 0 192.0.0.1:43245 192.0.68.1:49742 ESTABLISHED keepalive (1.99/0/4)
tcp 0 0 192.0.0.1:43245 192.0.68.1:49742 ESTABLISHED keepalive (0.85/0/4)
Yukarıda, her biri 10 saniye sonra sunucunun DÖRT tutma probları gönderdiğini ve herhangi bir yanıt almadığı için gönderilen probların sayısı arttığını ve 4'ten sonra istemciden ayrıldığını görebilirsiniz.
Port 2:
2. bağlantı için soket aynıydı, ancak sunucu tarafındaki uygulamam istemci düştükten sonra ve saklamanın süresi dolmadan önce bazı mesajlar göndermeye çalışıyordu:
netstat -c --timer | grep "192.0.0.1:36483 192.0.68.1:43881"
tcp 0 0 192.0.0.1:36483 192.0.68.1:43881 ESTABLISHED keepalive (8.18/0/1)
tcp 0 0 192.0.0.1:36483 192.0.68.1:43881 ESTABLISHED keepalive (7.00/0/1)
tcp 0 0 192.0.0.1:36483 192.0.68.1:43881 ESTABLISHED keepalive (5.86/0/1)
tcp 0 0 192.0.0.1:36483 192.0.68.1:43881 ESTABLISHED keepalive (4.71/0/1)
tcp 0 0 192.0.0.1:36483 192.0.68.1:43881 ESTABLISHED keepalive (3.55/0/1)
tcp 0 0 192.0.0.1:36483 192.0.68.1:43881 ESTABLISHED keepalive (2.40/0/1)
tcp 0 0 192.0.0.1:36483 192.0.68.1:43881 ESTABLISHED keepalive (1.21/0/1)
tcp 0 0 192.0.0.1:36483 192.0.68.1:43881 ESTABLISHED keepalive (0.05/0/1)
tcp 0 0 192.0.0.1:36483 192.0.68.1:43881 ESTABLISHED keepalive (8.91/0/2)
tcp 0 0 192.0.0.1:36483 192.0.68.1:43881 ESTABLISHED keepalive (7.75/0/2)
tcp 0 0 192.0.0.1:36483 192.0.68.1:43881 ESTABLISHED keepalive (6.56/0/2)
tcp 0 0 192.0.0.1:36483 192.0.68.1:43881 ESTABLISHED keepalive (5.39/0/2)
tcp 0 0 192.0.0.1:36483 192.0.68.1:43881 ESTABLISHED keepalive (4.14/0/2)
tcp 0 210 192.0.0.1:36483 192.0.68.1:43881 ESTABLISHED on (0.21/2/2) // <---- retransmission timer kicks in
tcp 0 210 192.0.0.1:36483 192.0.68.1:43881 ESTABLISHED on (0.68/3/2)
tcp 0 210 192.0.0.1:36483 192.0.68.1:43881 ESTABLISHED on (2.74/4/2)
tcp 0 210 192.0.0.1:36483 192.0.68.1:43881 ESTABLISHED on (1.59/4/2)
tcp 0 210 192.0.0.1:36483 192.0.68.1:43881 ESTABLISHED on (0.43/4/2)
tcp 0 210 192.0.0.1:36483 192.0.68.1:43881 ESTABLISHED on (2.28/5/2)
tcp 0 210 192.0.0.1:36483 192.0.68.1:43881 ESTABLISHED on (1.11/5/2)
tcp 0 210 192.0.0.1:36483 192.0.68.1:43881 ESTABLISHED on (2.95/6/2)
. . . . .
tcp 0 210 192.0.0.1:36483 192.0.68.1:43881 ESTABLISHED on (0.65/249/2)
tcp 0 210 192.0.0.1:36483 192.0.68.1:43881 ESTABLISHED on (2.58/250/2)
tcp 0 210 192.0.0.1:36483 192.0.68.1:43881 ESTABLISHED on (1.48/250/2)
tcp 0 210 192.0.0.1:36483 192.0.68.1:43881 ESTABLISHED on (0.36/250/2)
tcp 0 210 192.0.0.1:36483 192.0.68.1:43881 ESTABLISHED on (2.26/251/2)
tcp 0 210 192.0.0.1:36483 192.0.68.1:43881 ESTABLISHED on (1.15/251/2)
tcp 0 210 192.0.0.1:36483 192.0.68.1:43881 ESTABLISHED on (3.01/252/2)
tcp 0 210 192.0.0.1:36483 192.0.68.1:43881 ESTABLISHED on (1.92/252/2)
tcp 0 210 192.0.0.1:36483 192.0.68.1:43881 ESTABLISHED on (0.84/252/2)
tcp 0 210 192.0.0.1:36483 192.0.68.1:43881 ESTABLISHED on (2.72/253/2)
tcp 0 210 192.0.0.1:36483 192.0.68.1:43881 ESTABLISHED on (1.64/253/2)
tcp 0 210 192.0.0.1:36483 192.0.68.1:43881 ESTABLISHED on (0.55/253/2)
tcp 0 210 192.0.0.1:36483 192.0.68.1:43881 ESTABLISHED on (2.47/254/2)
tcp 0 210 192.0.0.1:36483 192.0.68.1:43881 ESTABLISHED on (1.39/254/2)
tcp 0 210 192.0.0.1:36483 192.0.68.1:43881 ESTABLISHED on (0.31/254/2)
tcp 0 210 192.0.0.1:36483 192.0.68.1:43881 ESTABLISHED on (2.19/255/2)
tcp 0 210 192.0.0.1:36483 192.0.68.1:43881 ESTABLISHED on (1.12/255/2)
Gördüğünüz gibi, bu durumda işler biraz farklı. İstemci kapandığında, sunucum saklayıcı iletiler göndermeye başladı, ancak yine de bu saklayıcıları gönderirken sunucum istemciye bir ileti göndermeye çalıştı. İstemci çöktüğünden, sunucu istemciden herhangi bir ACK alamadı, bu nedenle TCP yeniden iletimi başladı ve sunucu, her seferinde yeniden iletim zamanlayıcısını (2. alan) her yeniden iletme zamanlayıcısını (2. alan) artırmaya çalıştı. alanı) süresi doldu.
Umarım bu netstat --timer
seçeneği iyi açıklar .