Frame 6: 63 bytes on wire (504 bits), 63 bytes captured (504 bits) on interface \Device\NPF_{E6E18012-6BC3-40E2-87FD-B987B450CA13}, id 0 Section number: 1 Interface id: 0 (\Device\NPF_{E6E18012-6BC3-40E2-87FD-B987B450CA13}) Encapsulation type: Ethernet (1) Arrival Time: Aug 21, 2025 10:07:13.159693000 中国标准时间 UTC Arrival Time: Aug 21, 2025 02:07:13.159693000 UTC Epoch Arrival Time: 1755742033.159693000 [Time shift for this packet: 0.000000000 seconds] [Time delta from previous captured frame: 0.295483000 seconds] [Time delta from previous displayed frame: 0.295483000 seconds] [Time since reference or first frame: 12.017632000 seconds] Frame Number: 6 Frame Length: 63 bytes (504 bits) Capture Length: 63 bytes (504 bits) [Frame is marked: False] [Frame is ignored: False] [Protocols in frame: eth:ethertype:ip:tcp:data] [Coloring Rule Name: TCP] [Coloring Rule String: tcp] Ethernet II, Src: e0:d3:62:10:1a:55 (e0:d3:62:10:1a:55), Dst: 8c:86:dd:33:2f:28 (8c:86:dd:33:2f:28) Destination: 8c:86:dd:33:2f:28 (8c:86:dd:33:2f:28) … …0. … … … … = LG bit: Globally unique address (factory default) … …0 … … … … = IG bit: Individual address (unicast) Source: e0:d3:62:10:1a:55 (e0:d3:62:10:1a:55) … …0. … … … … = LG bit: Globally unique address (factory default) … …0 … … … … = IG bit: Individual address (unicast) Type: IPv4 (0x0800) [Stream index: 0] Internet Protocol Version 4, Src: 192.168.1.100, Dst: 192.168.3.101 0100 … = Version: 4 … 0101 = Header Length: 20 bytes (5) Differentiated Services Field: 0x00 (DSCP: CS0, ECN: Not-ECT) Total Length: 49 Identification: 0x5be7 (23527) 010. … = Flags: 0x2, Don’t fragment …0 0000 0000 0000 = Fragment Offset: 0 Time to Live: 128 Protocol: TCP (6) Header Checksum: 0x0000 [validation disabled] [Header checksum status: Unverified] Source Address: 192.168.1.100 Destination Address: 192.168.3.101 [Stream index: 0] Transmission Control Protocol, Src Port: 64166, Dst Port: 60000, Seq: 1, Ack: 1, Len: 9 Source Port: 64166 Destination Port: 60000 [Stream index: 0] [Conversation completeness: Complete, WITH_DATA (31)] [TCP Segment Len: 9] Sequence Number: 1 (relative sequence number) Sequence Number (raw): 387336689 [Next Sequence Number: 10 (relative sequence number)] Acknowledgment Number: 1 (relative ack number) Acknowledgment number (raw): 1889122141 0101 … = Header Length: 20 bytes (5) Flags: 0x018 (PSH, ACK) 000. … … = Reserved: Not set …0 … … = Accurate ECN: Not set … 0… … = Congestion Window Reduced: Not set … .0… … = ECN-Echo: Not set … …0. … = Urgent: Not set … …1 … = Acknowledgment: Set … … 1… = Push: Set … … .0… = Reset: Not set … … …0. = Syn: Not set … … …0 = Fin: Not set [TCP Flags: ·······AP···] Window: 255 [Calculated window size: 65280] [Window size scaling factor: 256] Checksum: 0x863d [unverified] [Checksum Status: Unverified] Urgent Pointer: 0 [Timestamps] [Time since first frame in this TCP stream: 12.017632000 seconds] [Time since previous frame in this TCP stream: 12.013701000 seconds] [SEQ/ACK analysis] [iRTT: 0.003931000 seconds] [Bytes in flight: 9] [Bytes sent since last PSH flag: 9] TCP payload (9 bytes) Data (9 bytes) Data: 313233343536373839 [Length: 9] Frame 7: 56 bytes on wire (448 bits), 56 bytes captured (448 bits) on interface \Device\NPF_{E6E18012-6BC3-40E2-87FD-B987B450CA13}, id 0 Section number: 1 Interface id: 0 (\Device\NPF_{E6E18012-6BC3-40E2-87FD-B987B450CA13}) Encapsulation type: Ethernet (1) Arrival Time: Aug 21, 2025 10:07:13.201939000 中国标准时间 UTC Arrival Time: Aug 21, 2025 02:07:13.201939000 UTC Epoch Arrival Time: 1755742033.201939000 [Time shift for this packet: 0.000000000 seconds] [Time delta from previous captured frame: 0.042246000 seconds] [Time delta from previous displayed frame: 0.042246000 seconds] [Time since reference or first frame: 12.059878000 seconds] Frame Number: 7 Frame Length: 56 bytes (448 bits) Capture Length: 56 bytes (448 bits) [Frame is marked: False] [Frame is ignored: False] [Protocols in frame: eth:ethertype:ip:tcp] [Coloring Rule Name: TCP] [Coloring Rule String: tcp] Ethernet II, Src: 8c:86:dd:33:2f:28 (8c:86:dd:33:2f:28), Dst: e0:d3:62:10:1a:55 (e0:d3:62:10:1a:55) Destination: e0:d3:62:10:1a:55 (e0:d3:62:10:1a:55) … …0. … … … … = LG bit: Globally unique address (factory default) … …0 … … … … = IG bit: Individual address (unicast) Source: 8c:86:dd:33:2f:28 (8c:86:dd:33:2f:28) … …0. … … … … = LG bit: Globally unique address (factory default) … …0 … … … … = IG bit: Individual address (unicast) Type: IPv4 (0x0800) [Stream index: 0] Trailer: 0000 Internet Protocol Version 4, Src: 192.168.3.101, Dst: 192.168.1.100 0100 … = Version: 4 … 0101 = Header Length: 20 bytes (5) Differentiated Services Field: 0x00 (DSCP: CS0, ECN: Not-ECT) Total Length: 40 Identification: 0x331f (13087) 010. … = Flags: 0x2, Don’t fragment …0 0000 0000 0000 = Fragment Offset: 0 Time to Live: 127 Protocol: TCP (6) Header Checksum: 0x4297 [validation disabled] [Header checksum status: Unverified] Source Address: 192.168.3.101 Destination Address: 192.168.1.100 [Stream index: 0] Transmission Control Protocol, Src Port: 60000, Dst Port: 64166, Seq: 1, Ack: 10, Len: 0 Source Port: 60000 Destination Port: 64166 [Stream index: 0] [Conversation completeness: Complete, WITH_DATA (31)] [TCP Segment Len: 0] Sequence Number: 1 (relative sequence number) Sequence Number (raw): 1889122141 [Next Sequence Number: 1 (relative sequence number)] Acknowledgment Number: 10 (relative ack number) Acknowledgment number (raw): 387336698 0101 … = Header Length: 20 bytes (5) Flags: 0x010 (ACK) 000. … … = Reserved: Not set …0 … … = Accurate ECN: Not set … 0… … = Congestion Window Reduced: Not set … .0… … = ECN-Echo: Not set … …0. … = Urgent: Not set … …1 … = Acknowledgment: Set … … 0… = Push: Not set … … .0… = Reset: Not set … … …0. = Syn: Not set … … …0 = Fin: Not set [TCP Flags: ·······A····] Window: 255 [Calculated window size: 65280] [Window size scaling factor: 256] Checksum: 0xbaac [unverified] [Checksum Status: Unverified] Urgent Pointer: 0 [Timestamps] [Time since first frame in this TCP stream: 12.059878000 seconds] [Time since previous frame in this TCP stream: 0.042246000 seconds] [SEQ/ACK analysis] [This is an ACK to the segment in frame: 6] [The RTT to ACK the segment was: 0.042246000 seconds] [iRTT: 0.003931000 seconds] listening on eth0, link-type EN10MB (Ethernet), capture size 65535 bytes 00:54:08.812647 IP 192.168.0.1.22 > 192.168.0.100.60319: Flags [P.], seq 2066893244:2066893356, ack 3794839666, win 1002, length 112 00:54:08.814409 IP 192.168.0.1.22 > 192.168.0.100.60319: Flags [P.], seq 112:320, ack 1, win 1002, length 208 00:54:08.815139 IP 192.168.0.100.60319 > 192.168.0.1.22: Flags [.], ack 320, win 251, length 0 00:54:09.821509 IP 192.168.0.1.22 > 192.168.0.100.60319: Flags [P.], seq 320:512, ack 1, win 1002, length 192 00:54:09.821680 IP 192.168.0.1.22 > 192.168.0.100.60319: Flags [P.], seq 512:784, ack 1, win 1002, length 272 00:54:09.822547 IP 192.168.0.100.60319 > 192.168.0.1.22: Flags [.], ack 784, win 255, length 0 00:54:10.844496 IP 192.168.0.1.22 > 192.168.0.100.60319: Flags [P.], seq 784:1152, ack 1, win 1002, length 368 00:54:10.897588 IP 192.168.0.100.60319 > 192.168.0.1.22: Flags [.], ack 1152, win 254, length 0 00:54:11.290370 IP 192.168.1.100.57933 > 192.168.1.1.53: 50024+ A? optimizationguide-pa.googleapis.com. (53) 00:54:11.290729 IP 192.168.1.1.53 > 192.168.1.100.57933: 50024 ServFail 0/0/0 (53) 00:54:11.291268 IP 192.168.1.100 > 192.168.1.1: ICMP 192.168.1.100 udp port 57933 unreachable, length 89 00:54:11.868777 IP 192.168.0.1.22 > 192.168.0.100.60319: Flags [P.], seq 1152:1424, ack 1, win 1002, length 272 00:54:11.869673 IP 192.168.0.1.22 > 192.168.0.100.60319: Flags [P.], seq 1424:1584, ack 1, win 1002, length 160 00:54:11.869787 IP 192.168.0.1.22 > 192.168.0.100.60319: Flags [P.], seq 1584:1824, ack 1, win 1002, length 240 00:54:11.870553 IP 192.168.0.100.60319 > 192.168.0.1.22: Flags [.], ack 1584, win 252, length 0 00:54:11.924818 IP 192.168.0.100.60319 > 192.168.0.1.22: Flags [.], ack 1824, win 251, length 0 00:54:12.892435 IP 192.168.0.1.22 > 192.168.0.100.60319: Flags [P.], seq 1824:2000, ack 1, win 1002, length 176 00:54:12.892673 IP 192.168.0.1.22 > 192.168.0.100.60319: Flags [P.], seq 2000:2480, ack 1, win 1002, length 480 00:54:12.893585 IP 192.168.0.100.60319 > 192.168.0.1.22: Flags [.], ack 2480, win 255, length 0 00:54:13.916503 IP 192.168.0.1.22 > 192.168.0.100.60319: Flags [P.], seq 2480:2864, ack 1, win 1002, length 384 00:54:13.962323 IP 192.168.0.100.60319 > 192.168.0.1.22: Flags [.], ack 2864, win 254, length 0 00:54:14.940463 IP 192.168.0.1.22 > 192.168.0.100.60319: Flags [P.], seq 2864:3136, ack 1, win 1002, length 272 00:54:14.989752 IP 192.168.0.100.60319 > 192.168.0.1.22: Flags [.], ack 3136, win 253, length 0 00:54:15.299954 IP 192.168.0.100.58105 > 192.168.3.101.60000: Flags [P.], seq 747139898:747139899, ack 2277206824, win 255, length 1 00:54:15.300131 ARP, Request who-has 192.168.3.101 tell 192.168.3.1, length 28 00:54:15.300988 ARP, Reply 192.168.3.101 is-at e0:d3:62:10:0f:3f (oui Unknown), length 46 00:54:15.301011 IP 192.168.3.1.58105 > 192.168.3.101.60000: Flags [P.], seq 747139898:747139899, ack 2277206824, win 255, length 1 00:54:15.351015 IP 192.168.3.101.60000 > 192.168.3.1.58105: Flags [.], ack 1, win 255, length 0 00:54:15.351118 IP 192.168.3.101.60000 > 192.168.0.100.58105: Flags [.], ack 1, win 255, length 0 00:54:15.964443 IP 192.168.0.1.22 > 192.168.0.100.60319: Flags [P.], seq 3136:3312, ack 1, win 1002, length 176 00:54:15.964643 IP 192.168.0.1.22 > 192.168.0.100.60319: Flags [P.], seq 3312:3472, ack 1, win 1002, length 160 00:54:15.965096 IP 192.168.0.1.22 > 192.168.0.100.60319: Flags [P.], seq 3472:3664, ack 1, win 1002, length 192 00:54:15.965463 IP 192.168.0.100.60319 > 192.168.0.1.22: Flags [.], ack 3472, win 252, length 0 00:54:15.965798 IP 192.168.0.1.22 > 192.168.0.100.60319: Flags [P.], seq 3664:3808, ack 1, win 1002, length 144 00:54:15.966026 IP 192.168.0.1.22 > 192.168.0.100.60319: Flags [P.], seq 3808:4288, ack 1, win 1002, length 480 00:54:15.966458 IP 192.168.0.100.60319 > 192.168.0.1.22: Flags [.], ack 3808, win 250, length 0 00:54:16.014638 IP 192.168.0.100.60319 > 192.168.0.1.22: Flags [.], ack 4288, win 255, length 0 00:54:16.211652 IP 192.168.0.100.58105 > 192.168.3.101.60000: Flags [P.], seq 1:2, ack 1, win 255, length 1 00:54:16.211815 IP 192.168.3.1.58105 > 192.168.3.101.60000: Flags [P.], seq 1:2, ack 1, win 255, length 1 00:54:16.267878 IP 192.168.3.101.60000 > 192.168.3.1.58105: Flags [.], ack 2, win 255, length 0 00:54:16.267982 IP 192.168.3.101.60000 > 192.168.0.100.58105: Flags [.], ack 2, win 255, length 0 00:54:16.988822 IP 192.168.0.1.22 > 192.168.0.100.60319: Flags [P.], seq 4288:5616, ack 1, win 1002, length 1328 00:54:17.040537 IP 192.168.0.100.60319 > 192.168.0.1.22: Flags [.], ack 5616, win 250, length 0 00:54:17.916230 IP 192.168.0.1.54004 > 255.255.255.255.29810: UDP, length 521 00:54:18.012792 IP 192.168.0.1.22 > 192.168.0.100.60319: Flags [P.], seq 5616:5888, ack 1, win 1002, length 272 00:54:18.013131 IP 192.168.0.1.22 > 192.168.0.100.60319: Flags [P.], seq 5888:6032, ack 1, win 1002, length 144 00:54:18.013899 IP 192.168.0.100.60319 > 192.168.0.1.22: Flags [.], ack 6032, win 255, length 0 00:54:19.036493 IP 192.168.0.1.22 > 192.168.0.100.60319: Flags [P.], seq 6032:6416, ack 1, win 1002, length 384 00:54:19.088657 IP 192.168.0.100.60319 > 192.168.0.1.22: Flags [.], ack 6416, win 254, length 0 00:54:20.060458 IP 192.168.0.1.22 > 192.168.0.100.60319: Flags [P.], seq 6416:6688, ack 1, win 1002, length 272 00:54:20.112309 IP 192.168.0.100.60319 > 192.168.0.1.22: Flags [.], ack 6688, win 253, length 0 00:54:20.161769 ARP, Request who-has 192.168.3.1 (8c:86:dd:33:2f:2c (oui Unknown)) tell 192.168.3.101, length 46 00:54:20.161838 ARP, Reply 192.168.3.1 is-at 8c:86:dd:33:2f:2c (oui Unknown), length 28 00:54:21.084556 IP 192.168.0.1.22 > 192.168.0.100.60319: Flags [P.], seq 6688:7152, ack 1, win 1002, length 464 00:54:21.137446 IP 192.168.0.100.60319 > 192.168.0.1.22: Flags [.], ack 7152, win 251, length 0 00:54:22.108460 IP 192.168.0.1.22 > 192.168.0.100.60319: Flags [P.], seq 7152:7424, ack 1, win 1002, length 272 00:54:22.161746 IP 192.168.0.100.60319 > 192.168.0.1.22: Flags [.], ack 7424, win 250, length 0 00:54:23.132461 IP 192.168.0.1.22 > 192.168.0.100.60319: Flags [P.], seq 7424:7696, ack 1, win 1002, length 272 00:54:23.187595 IP 192.168.0.100.60319 > 192.168.0.1.22: Flags [.], ack 7696, win 255, length 0 00:54:24.156459 IP 192.168.0.1.22 > 192.168.0.100.60319: Flags [P.], seq 7696:7968, ack 1, win 1002, length 272 00:54:24.211727 IP 192.168.0.100.60319 > 192.168.0.1.22: Flags [.], ack 7968, win 254, length 0 00:54:25.180454 IP 192.168.0.1.22 > 192.168.0.100.60319: Flags [P.], seq 7968:8240, ack 1, win 1002, length 272 00:54:25.233308 IP 192.168.0.100.60319 > 192.168.0.1.22: Flags [.], ack 8240, win 253, length 0 00:54:26.204492 IP 192.168.0.1.22 > 192.168.0.100.60319: Flags [P.], seq 8240:8512, ack 1, win 1002, length 272 00:54:26.258181 IP 192.168.0.100.60319 > 192.168.0.1.22: Flags [.], ack 8512, win 252, length 0 00:54:27.228475 IP 192.168.0.1.22 > 192.168.0.100.60319: Flags [P.], seq 8512:8784, ack 1, win 1002, length 272 00:54:27.283643 IP 192.168.0.100.60319 > 192.168.0.1.22: Flags [.], ack 8784, win 251, length 0 00:54:27.988247 IP 192.168.0.1.54004 > 255.255.255.255.29810: UDP, length 521 00:54:28.252496 IP 192.168.0.1.22 > 192.168.0.100.60319: Flags [P.], seq 8784:9136, ack 1, win 1002, length 352 00:54:28.296458 IP 192.168.0.100.60319 > 192.168.0.1.22: Flags [.], ack 9136, win 250, length 0 00:54:29.276447 IP 192.168.0.1.22 > 192.168.0.100.60319: Flags [P.], seq 9136:9312, ack 1, win 1002, length 176 00:54:29.276614 IP 192.168.0.1.22 > 192.168.0.100.60319: Flags [P.], seq 9312:9472, ack 1, win 1002, length 160 00:54:29.277521 IP 192.168.0.100.60319 > 192.168.0.1.22: Flags [.], ack 9472, win 255, length 0 00:54:29.299489 IP 192.168.0.100.60319 > 192.168.0.1.22: Flags [P.], seq 1:161, ack 9472, win 255, length 160 00:54:29.299700 IP 192.168.0.1.22 > 192.168.0.100.60319: Flags [P.], seq 9472:9520, ack 161, win 1002, length 48 00:54:29.352007 IP 192.168.0.100.60319 > 192.168.0.1.22: Flags [.], ack 9520, win 255, length 0 root@ER7206:/# ip route 127.0.0.0/8 dev lo scope link 169.254.11.20/30 dev br-lan scope link 192.168.0.0/24 dev inf.1 proto kernel scope link src 192.168.0.1 192.168.1.0/24 dev inf.2 proto kernel scope link src 192.168.1.1 192.168.2.0/24 dev inf.3 proto kernel scope link src 192.168.2.1 192.168.3.0/24 dev inf.4091 scope link root@ER7206:/# ip rule 0: from all lookup local 25: from all fwmark 0x20000/0x20000 lookup 25 27: from all lookup link 29: from all lookup lan 221: from all fwmark 0x20000/0x20000 lookup 221 20044: from 192.168.3.1 lookup wan4_eth 32766: from all lookup main 32767: from all lookup default以上是相关信息,请分析说明
时间: 2025-08-21 12:06:57 AIGC 浏览: 38
<think>我们首先需要分析用户提供的数据包信息以及路由和规则信息。用户提供了两个主要的数据包(Frame 6和Frame 7)以及后续的一些网络流量,还有路由表和规则表。
目标:分析网络通信情况,特别是关于192.168.1.100与192.168.3.101之间的通信。
步骤:
1. 分析Frame 6和Frame 7:
Frame 6:
- 源MAC: e0:d3:62:10:1a:55 (PC1:192.168.1.100)
- 目标MAC: 8c:86:dd:33:2f:28 (PC2:192.168.3.101) ?但是注意,在同一个以太网中,源主机应该先将数据包发送给网关,而不是直接发给目标主机(因为目标主机在另一个子网)。所以这里的目标MAC应该是网关的MAC?但是这里的目标MAC是8c:86:dd:33:2f:28,而网关的接口MAC我们后面需要确定。
- 但是,在Frame 6中,目标MAC是8c:86:dd:33:2f:28,而源MAC是e0:d3:62:10:1a:55。根据后续的ARP请求,我们注意到192.168.3.101的MAC是e0:d3:62:10:0f:3f(在00:54:15.300988处),而192.168.3.1的MAC是8c:86:dd:33:2f:2c(在ARP Reply中)。所以这里的目标MAC 8c:86:dd:33:2f:28并不是192.168.3.101的MAC(因为192.168.3.101的MAC是e0:d3:62:10:0f:3f),也不是网关在LAN1口的MAC(因为网关在LAN1口连接192.168.1.0/24,其MAC应该是?)。这里需要澄清。
2. 实际上,在Frame 6中,源IP是192.168.1.100,目标IP是192.168.3.101。由于192.168.3.101不在同一个子网,所以PC1应该将数据包发送给默认网关(即192.168.1.1)。因此,目标MAC应该是网关在LAN1接口的MAC。但是这里的目标MAC是8c:86:dd:33:2f:28,我们需要确认这个MAC是否是网关的MAC。
3. 查看路由表(ip route):
- 192.168.0.0/24 dev inf.1 ... (网关地址192.168.0.1)
- 192.168.1.0/24 dev inf.2 ... (网关地址192.168.1.1)
- 192.168.2.0/24 dev inf.3 ...
- 192.168.3.0/24 dev inf.4091 ... (没有指定IP,但根据上下文,网关在192.168.3.0/24网段应该是192.168.3.1)
4. 在ARP请求中,我们看到:
- 00:54:20.161769 ARP, Request who-has 192.168.3.1 tell 192.168.3.101 -> 说明192.168.3.1的MAC是8c:86:dd:33:2f:2c(在回复中)。
- 但是Frame6的目标MAC是8c:86:dd:33:2f:28,与8c:86:dd:33:2f:2c很相似,可能是同一个设备的另一个接口?或者可能是笔误?
5. 注意:在Frame6中,目标MAC是8c:86:dd:33:2f:28,而源MAC是e0:d3:62:10:1a:55。在Frame7中(响应包):
- 源MAC: 8c:86:dd:33:2f:28 (与Frame6的目标MAC相同)
- 目标MAC: e0:d3:62:10:1a:55 (PC1的MAC)
所以,这个8c:86:dd:33:2f:28的设备实际上就是网关设备,因为它在收到Frame6后,生成了Frame7(TCP ACK)返回给PC1。但是,这个ACK包是网关自己返回的?还是从PC2返回的?注意Frame7的IP层:源IP是192.168.3.101(PC2),目标IP是192.168.1.100(PC1)。但是,这个包是通过网关转发的,为什么源MAC是网关的MAC(8c:86:dd:33:2f:28)而不是PC2的MAC?因为PC2在另一个网络,所以当网关收到PC2的响应包时,它会把PC2的MAC替换为自己的MAC(目标MAC改为PC1的MAC)?这不符合常规的转发行为。
6. 实际上,在Frame7中,以太网帧的源MAC是网关的MAC(8c:86:dd:33:2f:28),目标MAC是PC1的MAC(e0:d3:62:10:1a:55)。而IP包内的源IP是PC2(192.168.3.101),目标IP是PC1(192.168.1.100)。这是正常的,因为网关在转发时修改了MAC层,但保留了IP层。
7. 但是,在Frame6中,为什么PC1会将目标MAC设为网关的MAC(8c:86:dd:33:2f:28)?因为PC1要发送给另一个网络的PC2,所以它会把数据包发送给网关,因此目标MAC是网关的MAC。所以,8c:86:dd:33:2f:28应该是网关在LAN1(192.168.1.0/24)接口的MAC地址。
8. 然而,在ARP请求中,我们看到了网关在LAN3(192.168.3.0/24)接口的MAC是8c:86:dd:33:2f:2c。所以网关的不同接口有不同的MAC地址,这是正常的。
9. 因此,通信流程:
- PC1(192.168.1.100)要发送数据给PC2(192.168.3.101),它先将数据包发送给网关(192.168.1.1),目标MAC为网关LAN1接口的MAC(8c:86:dd:33:2f:28)。
- 网关收到后,根据目标IP(192.168.3.101)查询路由表,发现应该从LAN3接口(inf.4091)转发。然后它需要将数据包转发给PC2。但是,网关需要知道PC2的MAC地址,所以会发送ARP请求(如我们在00:54:15.300131看到的,网关请求192.168.3.101的MAC)。
- 在00:54:15.300988,PC2回复了ARP,告知其MAC为e0:d3:62:10:0f:3f。
- 然后网关将数据包重新封装,源MAC改为网关LAN3接口的MAC(8c:86:dd:33:2f:2c),目标MAC为PC2的MAC(e0:d3:62:10:0f:3f),然后发送给PC2。
- PC2收到后,生成TCP ACK(注意:在Frame7中,我们看到的是网关直接返回的ACK?但实际上不是,Frame7是PC2返回的ACK经过网关转发给PC1的包)。
10. 但是,在Frame6和Frame7之间,我们并没有在捕获的数据中看到网关转发给PC2的包以及PC2返回的包?因为捕获点可能在网关的LAN1接口上,所以只能看到进出LAN1接口的包。
11. 所以,在LAN1接口上,我们只能看到:
Frame6: PC1 -> 网关 (目标MAC为网关LAN1的MAC)
Frame7: 网关 -> PC1 (源MAC为网关LAN1的MAC,这个包是PC2的响应经过网关转发后,从网关的LAN1接口发出来的)
12. 因此,整个路径是正常的。
13. 另外,在后续的流量中,我们看到了大量192.168.0.1.22(SSH)与192.168.0.100.60319的通信,这是另一个网络的通信。
14. 还有,在00:54:15.299954处,我们看到192.168.0.100.58105发送给192.168.3.101.60000的TCP包,但是注意,192.168.0.100与192.168.3.101不在同一网络,所以它需要经过网关。但是,在发送之前,它需要先发送ARP请求网关的MAC吗?但是这里没有直接发送ARP,而是先发送了一个目标为192.168.3.101.60000的数据包(目标MAC应该是网关在192.168.0.0/24网段的接口MAC)。然后,在00:54:15.300131,我们看到网关(192.168.3.1)发送ARP请求192.168.3.101的MAC(因为网关需要将数据包转发给PC2,但不知道PC2的MAC)。然后PC2回复ARP,网关再转发数据包。
15. 路由规则(ip rule):
- 有多个策略路由,例如标记0x20000的包分别查找表25和221。
- 还有一条:20044: from 192.168.3.1 lookup wan4_eth
- 默认查找main表(32766)和default表(32767)
16. 在路由表(ip route)中,我们看到了多个直连路由,以及一个默认路由?没有看到默认路由,但是有多个网段的路由。
17. 对于192.168.3.0/24的流量,网关使用接口inf.4091。
总结:网络通信正常,网关正确转发了跨网段的数据包。
但是,用户可能希望我们分析为什么Frame6和Frame7会这样?以及整个通信过程。
根据以上分析,我们给出回答。</think>### 网络通信分析报告
#### 1. 跨网段TCP通信流程(Frame 6-7)
- **通信路径**:
```mermaid
flowchart LR
PC1[192.168.1.100] -->|1. 封装网关MAC| Gateway[网关 192.168.1.1]
Gateway -->|2. 路由转发| PC2[192.168.3.101]
PC2 -->|3. ACK响应| Gateway
Gateway -->|4. 返回PC1| PC1
```
- **关键细节**:
- **Frame 6**(PC1→PC2):
- 源MAC:`e0:d3:62:10:1a:55`(PC1)
- 目标MAC:`8c:86:dd:33:2f:28`(网关LAN1接口)
- TCP载荷:9字节ASCII "123456789"(十六进制`313233...`)
- 标志位:PSH+ACK(数据推送确认)
- **Frame 7**(PC2→PC1):
- TTL从128→127(每经过一跳减1)
- 纯ACK确认包(长度0),序列号匹配Frame6的载荷
#### 2. 路由与转发机制
- **路由表分析**(`ip route`):
```bash
192.168.0.0/24 dev inf.1 # VLAN1接口
192.168.1.0/24 dev inf.2 # VLAN2接口
192.168.3.0/24 dev inf.4091 # VLAN4091接口(直连)
```
- **策略路由**(`ip rule`):
- 源IP `192.168.3.1` 强制走 `wan4_eth` 表(策略路由20044)
- 默认流量走主路由表(32766)
#### 3. ARP协议交互过程
- **跨网段ARP示例**(00:54:15.300131):
```mermaid
sequenceDiagram
网关->>+PC2: ARP请求 (Who-has 192.168.3.101?)
PC2-->>-网关: ARP响应 (is-at e0:d3:62:10:0f:3f)
网关->>PC2: 转发TCP数据包
```
- **本地ARP维护**(00:54:20.161769):
- PC2主动刷新网关MAC:`192.168.3.1 → 8c:86:dd:33:2f:2c`
#### 4. 异常流量诊断
- **DNS解析失败**(00:54:11.290729):
- PC1(192.168.1.100)查询 `optimizationguide-pa.googleapis.com`
- 网关返回 `ServFail` 响应,触发ICMP端口不可达(代码3)
- **UDP广播流量**(00:54:17.916230):
- 网关向 `255.255.255.255:29810` 发送521字节UDP包(疑似服务发现)
#### 5. SSH长连接分析
- **持续数据流**(端口60319):
- 窗口大小动态调整(win=1002→255)
- 大文件传输特征:分片长度多为272/176字节
- 零窗口探测:接收方ACK延迟≈40ms(见00:54:09.822547)
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