我从 Arduino 发送了一个 UDP 数据包，该数据包到达我的 Ubuntu 服务器，因为您可以在 tcpdump 上看到它，如您所见。但它从未转发到正在监听端口 8888 的应用程序。有人知道数据包出了什么问题吗？
我的 Ubuntu 版本是：Ubuntu 12.04.1 LTS（GNU/Linux 3.2.0-29-generic-pae i686）
这是tcpdump：
tcpdump -i 1 udp port 8888 -vv -X
tcpdump: listening on eth0, link-type EN10MB (Ethernet), capture size 65535 byte s
19:06:20.179117 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto UDP (17), length 131)
192.168.1.53.3333 > diskServer.8888: [udp sum ok] UDP, length 103
0x0000: 4500 0083 0000 4000 4011 b6b1 c0a8 0135 E.....@[email protected]
0x0010: c0a8 0133 0d05 22b8 006f 87d6 7465 7374 ...3.."..o..test
0x0020: 2030 3132 3334 3536 3738 3930 2074 6573 .01234567890.tes
0x0030: 7420 3031 3233 3435 3637 3839 3020 7465 t.01234567890.te
0x0040: 7374 2030 3132 3334 3536 3738 3930 2074 st.01234567890.t
0x0050: 6573 7420 3031 3233 3435 3637 3839 3020 est.01234567890.
0x0060: 7465 7374 2030 3132 3334 3536 3738 3930 test.01234567890
0x0070: 2074 6573 7420 3031 3233 3435 3637 3839 .test.0123456789
0x0080: 3020 00 0..
这是监听端口：
root@diskServer:~# netstat -a
Active Internet connections (servers and established)
Proto Recv-Q Send-Q Local Address Foreign Address State
tcp 0 0 diskServer:mysql *:* LISTEN
tcp 0 0 *:netbios-ssn *:* LISTEN
tcp 0 0 *:ssh *:* LISTEN
tcp 0 0 *:https *:* LISTEN
tcp 0 0 *:microsoft-ds *:* LISTEN
tcp 0 0 diskServer:ssh flavix:53077 ESTABLISHED
tcp 0 144 diskServer:ssh flavix:53028 ESTABLISHED
tcp 0 0 diskServer:ssh 192.168.1.107:54978 ESTABLISHED
tcp 0 0 diskServer:ssh 192.168.1.107:55000 ESTABLISHED
tcp6 0 0 [::]:8009 [::]:* LISTEN
tcp6 0 0 [::]:http-alt [::]:* LISTEN
tcp6 0 0 [::]:ssh [::]:* LISTEN
tcp6 0 0 [::]:8443 [::]:* LISTEN
tcp6 0 0 localhost:8005 [::]:* LISTEN
udp 0 0 diskServer:ntp *:*
udp 0 0 localhost:ntp *:*
udp 0 0 *:ntp *:*
udp 0 0 192.168.1.25:netbios-ns *:*
udp 0 0 diskServer:netbios-ns *:*
udp 0 0 *:netbios-ns *:*
udp 0 0 192.168.1.2:netbios-dgm *:*
udp 0 0 diskServer:netbios-dgm *:*
udp 0 0 *:netbios-dgm *:*
udp 0 0 diskServer:8888 *:***
udp6 0 0 ip6-localhost:ntp [::]:*
udp6 0 0 fe80::20e:7bff:feac:ntp [::]:*
udp6 0 0 [::]:ntp [::]:*
UDP 的记忆：
root@diskServer:~# cat /proc/sys/net/ipv4/udp_mem
18066 24090 36132
root@diskServer:~# netstat -su
IcmpMsg:
InType3: 10316969
InType8: 18368
OutType0: 18368
OutType3: 10317030
Udp:
211263 packets received
10309092 packets to unknown port received.
0 packet receive errors
10348446 packets sent
UdpLite:
IpExt:
InMcastPkts: 24678
InBcastPkts: 287164
OutBcastPkts: 12685
InOctets: -1
OutOctets: -1
InMcastOctets: 690984
InBcastOctets: 48281994
OutBcastOctets: 3170039
root@diskServer:~# iptables -L
Chain INPUT (policy ACCEPT)
target prot opt source destination
fail2ban-apache-badbots tcp -- anywhere anywhere multiport dports http,https
fail2ban-apache-overflows tcp -- anywhere anywhere multiport dports http,https
fail2ban-apache-noscript tcp -- anywhere anywhere multiport dports http,https
fail2ban-apache tcp -- anywhere anywhere multiport dports http,https
fail2ban-ssh tcp -- anywhere anywhere multiport dports ssh
ufw-before-logging-input all -- anywhere anywhere
ufw-before-input all -- anywhere anywhere
ufw-after-input all -- anywhere anywhere
ufw-after-logging-input all -- anywhere anywhere
ufw-reject-input all -- anywhere anywhere
ufw-track-input all -- anywhere anywhere
Chain FORWARD (policy ACCEPT)
target prot opt source destination
ufw-before-logging-forward all -- anywhere anywhere
ufw-before-forward all -- anywhere anywhere
ufw-after-forward all -- anywhere anywhere
ufw-after-logging-forward all -- anywhere anywhere
ufw-reject-forward all -- anywhere anywhere
Chain OUTPUT (policy ACCEPT)
target prot opt source destination
ufw-before-logging-output all -- anywhere anywhere
ufw-before-output all -- anywhere anywhere
ufw-after-output all -- anywhere anywhere
ufw-after-logging-output all -- anywhere anywhere
ufw-reject-output all -- anywhere anywhere
ufw-track-output all -- anywhere anywhere
Chain fail2ban-apache (1 references)
target prot opt source destination
RETURN all -- anywhere anywhere
Chain fail2ban-apache-badbots (1 references)
target prot opt source destination
RETURN all -- anywhere anywhere
Chain fail2ban-apache-noscript (1 references)
target prot opt source destination
RETURN all -- anywhere anywhere
Chain fail2ban-apache-overflows (1 references)
target prot opt source destination
RETURN all -- anywhere anywhere
Chain fail2ban-ssh (1 references)
target prot opt source destination
RETURN all -- anywhere anywhere
Chain ufw-after-forward (1 references)
target prot opt source destination
Chain ufw-after-input (1 references)
target prot opt source destination
Chain ufw-after-logging-forward (1 references)
target prot opt source destination
Chain ufw-after-logging-input (1 references)
target prot opt source destination
Chain ufw-after-logging-output (1 references)
target prot opt source destination
Chain ufw-after-output (1 references)
target prot opt source destination
Chain ufw-before-forward (1 references)
target prot opt source destination
Chain ufw-before-input (1 references)
target prot opt source destination
Chain ufw-before-logging-forward (1 references)
target prot opt source destination
Chain ufw-before-logging-input (1 references)
target prot opt source destination
Chain ufw-before-logging-output (1 references)
target prot opt source destination
Chain ufw-before-output (1 references)
target prot opt source destination
Chain ufw-reject-forward (1 references)
target prot opt source destination
Chain ufw-reject-input (1 references)
target prot opt source destination
Chain ufw-reject-output (1 references)
target prot opt source destination
Chain ufw-track-input (1 references)
target prot opt source destination
Chain ufw-track-output (1 references)
target prot opt source destination
ufw 已被禁用。
答案1
问题出在数据包中，这是错误的，因为以太网级别的目的地设置为 0，这是 wireShark 的输出：
以太网 II，源：74：69：69：2d：30：31（74：69：69：2d：30：31），目标：00：00：00_00：00：00（00：00：00：00：00：00）
这是因为我的 Arduino 开发板存在硬件问题。
谢谢大家，再见。
答案2
实际问题可能出在使用的 ethercard 库中。它没有正确处理目标的 ARP 查找，导致目标 mac 地址全为零（请参阅https://github.com/jcw/ethercard/issues/181）。
另一个可行的库是 Ethernet_UIP，可以在以下位置找到：https://github.com/ntruchsess/arduino_uip其中有一个发送 UDP 数据包的示例；我测试了该示例并且它确实有效。