linux mtu =1500情况下tcpdump抓包分析

node2:/root/test#netstat -in
Kernel Interface table
Iface       MTU Met    RX-OK RX-ERR RX-DRP RX-OVR    TX-OK TX-ERR TX-DRP TX-OVR Flg
eth1       1500   0   318073      0      0      0   411512      0      0      0 BMRU
lo        16436   0   168243      0      0      0   168243      0      0      0 LRU



node1:/root#netstat -i
Kernel Interface table
Iface       MTU Met    RX-OK RX-ERR RX-DRP RX-OVR    TX-OK TX-ERR TX-DRP TX-OVR Flg
eth1       1500   0  2060917      0      0      0  1718001      0      0      0 BMRU
lo        16436   0   238247      0      0      0   238247      0      0      0 LRU



node2:/root/test#python t16.py 
1500

发送1500数据:


node2:/root#tcpdump -S -i eth1 '((tcp) and  (port 8080) and (host 192.168.137.2))'
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on eth1, link-type EN10MB (Ethernet), capture size 65535 bytes
14:32:27.565653 IP node2.34070 > node1.webcache: Flags [S], seq 1323596397, win 14600, options [mss 1460,sackOK,TS val 121389260 ecr 0,nop,wscale 7], length 0
14:32:27.565858 IP node1.webcache > node2.34070: Flags [S.], seq 753559329, ack 1323596398, win 14480, options [mss 1460,sackOK,TS val 46393088 ecr 121389260,nop,wscale 6], length 0
14:32:27.565872 IP node2.34070 > node1.webcache: Flags [.], ack 753559330, win 115, options [nop,nop,TS val 121389260 ecr 46393088], length 0

14:32:27.565959 IP node2.34070 > node1.webcache: Flags [.], seq 1323596398:1323597846, ack 753559330, win 115, options [nop,nop,TS val 121389260 ecr 46393088], length 1448
14:32:27.565991 IP node2.34070 > node1.webcache: Flags [P.], seq 1323597846:1323597898, ack 753559330, win 115, options [nop,nop,TS val 121389260 ecr 46393088], length 52

1448+52

14:32:27.566034 IP node2.34070 > node1.webcache: Flags [F.], seq 1323597898, ack 753559330, win 115, options [nop,nop,TS val 121389260 ecr 46393088], length 0
14:32:27.566565 IP node1.webcache > node2.34070: Flags [.], ack 1323597846, win 272, options [nop,nop,TS val 46393088 ecr 121389260], length 0
14:32:27.566576 IP node1.webcache > node2.34070: Flags [.], ack 1323597898, win 272, options [nop,nop,TS val 46393088 ecr 121389260], length 0
14:32:27.566578 IP node1.webcache > node2.34070: Flags [F.], seq 753559330, ack 1323597899, win 272, options [nop,nop,TS val 46393088 ecr 121389260], length 0
14:32:27.566582 IP node2.34070 > node1.webcache: Flags [.], ack 753559331, win 115, options [nop,nop,TS val 121389261 ecr 46393088], length 0