通过 Linux tap 设备的 TCP 隧道
TCP tunneling through Linux tap device
我已经创建了一个 tap0 设备（IP 10.0.0.101），并且正在使用 zeromq 的 pgm pub/sub（例如 pgm://192.168.100.2;234.5.6.7:5555）从点击 zmq 订阅者，反之亦然。这个想法是使用 pgm 创建一个虚拟网络。我在网络上有 2 个 Tap 主机：10.0.0.101、10.0.0.11。他们在 192.168.106.126、192.168.106.55 也有物理以太网适配器。
'问题是 ping 有效，但 http 和 ssh 协议无效。
Wireshark 显示成功的 TCP 启动序列，但随后我开始看到重复的 ACK、重传，并且 curl 和 ssh 挂起一段时间并最终出错。
下面是 Wireshark 的一个片段，后面是大部分（希望如此）相关的 ruby 源代码。这是使用 rb_tuntap 和 ffi-rzmq 宝石。
No. Time Source Destination Protocol Length Info
7 11:41:45.464867000 10.0.0.11 10.0.0.101 TCP 74 51659 > 3000 [SYN] Seq=0 Win=14600 Len=0 MSS=1460 SACK_PERM=1 TSval=1953042 TSecr=0 WS=64
Frame 7: 74 bytes on wire (592 bits), 74 bytes captured (592 bits) on interface 0
Ethernet II, Src: 3a:e2:d5:f3:8e:6f (3a:e2:d5:f3:8e:6f), Dst: 56:c8:52:17:31:67 (56:c8:52:17:31:67)
Internet Protocol Version 4, Src: 10.0.0.11 (10.0.0.11), Dst: 10.0.0.101 (10.0.0.101)
Transmission Control Protocol, Src Port: 51659 (51659), Dst Port: 3000 (3000), Seq: 0, Len: 0
No. Time Source Destination Protocol Length Info
8 11:41:45.464956000 10.0.0.101 10.0.0.11 TCP 74 3000 > 51659 [SYN, ACK] Seq=0 Ack=1 Win=28960 Len=0 MSS=1460 SACK_PERM=1 TSval=10191992 TSecr=1953042 WS=128
Frame 8: 74 bytes on wire (592 bits), 74 bytes captured (592 bits) on interface 0
Ethernet II, Src: 56:c8:52:17:31:67 (56:c8:52:17:31:67), Dst: 3a:e2:d5:f3:8e:6f (3a:e2:d5:f3:8e:6f)
Internet Protocol Version 4, Src: 10.0.0.101 (10.0.0.101), Dst: 10.0.0.11 (10.0.0.11)
Transmission Control Protocol, Src Port: 3000 (3000), Dst Port: 51659 (51659), Seq: 0, Ack: 1, Len: 0
No. Time Source Destination Protocol Length Info
11 11:41:45.473101000 10.0.0.11 10.0.0.101 TCP 66 51659 > 3000 [ACK] Seq=1 Ack=1 Win=14656 Len=0 TSval=1953044 TSecr=10191992
Frame 11: 66 bytes on wire (528 bits), 66 bytes captured (528 bits) on interface 0
Ethernet II, Src: 3a:e2:d5:f3:8e:6f (3a:e2:d5:f3:8e:6f), Dst: 56:c8:52:17:31:67 (56:c8:52:17:31:67)
Internet Protocol Version 4, Src: 10.0.0.11 (10.0.0.11), Dst: 10.0.0.101 (10.0.0.101)
Transmission Control Protocol, Src Port: 51659 (51659), Dst Port: 3000 (3000), Seq: 1, Ack: 1, Len: 0
No. Time Source Destination Protocol Length Info
12 11:41:45.473429000 10.0.0.11 10.0.0.101 HTTP 145 GET / HTTP/1.1
Frame 12: 145 bytes on wire (1160 bits), 145 bytes captured (1160 bits) on interface 0
Ethernet II, Src: 3a:e2:d5:f3:8e:6f (3a:e2:d5:f3:8e:6f), Dst: 56:c8:52:17:31:67 (56:c8:52:17:31:67)
Internet Protocol Version 4, Src: 10.0.0.11 (10.0.0.11), Dst: 10.0.0.101 (10.0.0.101)
Transmission Control Protocol, Src Port: 51659 (51659), Dst Port: 3000 (3000), Seq: 1, Ack: 1, Len: 79
Hypertext Transfer Protocol
No. Time Source Destination Protocol Length Info
13 11:41:45.473460000 10.0.0.101 10.0.0.11 TCP 66 3000 > 51659 [ACK] Seq=1 Ack=80 Win=29056 Len=0 TSval=10192001 TSecr=1953046
Frame 13: 66 bytes on wire (528 bits), 66 bytes captured (528 bits) on interface 0
Ethernet II, Src: 56:c8:52:17:31:67 (56:c8:52:17:31:67), Dst: 3a:e2:d5:f3:8e:6f (3a:e2:d5:f3:8e:6f)
Internet Protocol Version 4, Src: 10.0.0.101 (10.0.0.101), Dst: 10.0.0.11 (10.0.0.11)
Transmission Control Protocol, Src Port: 3000 (3000), Dst Port: 51659 (51659), Seq: 1, Ack: 80, Len: 0
No. Time Source Destination Protocol Length Info
15 11:41:45.491555000 10.0.0.101 10.0.0.11 TCP 717 [TCP segment of a reassembled PDU]
Frame 15: 717 bytes on wire (5736 bits), 717 bytes captured (5736 bits) on interface 0
Ethernet II, Src: 56:c8:52:17:31:67 (56:c8:52:17:31:67), Dst: 3a:e2:d5:f3:8e:6f (3a:e2:d5:f3:8e:6f)
Internet Protocol Version 4, Src: 10.0.0.101 (10.0.0.101), Dst: 10.0.0.11 (10.0.0.11)
Transmission Control Protocol, Src Port: 3000 (3000), Dst Port: 51659 (51659), Seq: 1, Ack: 80, Len: 651
No. Time Source Destination Protocol Length Info
16 11:41:45.491599000 10.0.0.101 10.0.0.11 TCP 1514 [TCP segment of a reassembled PDU]
Frame 16: 1514 bytes on wire (12112 bits), 1514 bytes captured (12112 bits) on interface 0
Ethernet II, Src: 56:c8:52:17:31:67 (56:c8:52:17:31:67), Dst: 3a:e2:d5:f3:8e:6f (3a:e2:d5:f3:8e:6f)
Internet Protocol Version 4, Src: 10.0.0.101 (10.0.0.101), Dst: 10.0.0.11 (10.0.0.11)
Transmission Control Protocol, Src Port: 3000 (3000), Dst Port: 51659 (51659), Seq: 652, Ack: 80, Len: 1448
No. Time Source Destination Protocol Length Info
21 11:41:45.496998000 10.0.0.11 10.0.0.101 TCP 66 51659 > 3000 [ACK] Seq=80 Ack=652 Win=17536 Len=0 TSval=1953058 TSecr=10192019
Frame 21: 66 bytes on wire (528 bits), 66 bytes captured (528 bits) on interface 0
Ethernet II, Src: 3a:e2:d5:f3:8e:6f (3a:e2:d5:f3:8e:6f), Dst: 56:c8:52:17:31:67 (56:c8:52:17:31:67)
Internet Protocol Version 4, Src: 10.0.0.11 (10.0.0.11), Dst: 10.0.0.101 (10.0.0.101)
Transmission Control Protocol, Src Port: 51659 (51659), Dst Port: 3000 (3000), Seq: 80, Ack: 652, Len: 0
No. Time Source Destination Protocol Length Info
22 11:41:45.497026000 10.0.0.101 10.0.0.11 HTTP 231 HTTP/1.1 200 OK (text/html)
Frame 22: 231 bytes on wire (1848 bits), 231 bytes captured (1848 bits) on interface 0
Ethernet II, Src: 56:c8:52:17:31:67 (56:c8:52:17:31:67), Dst: 3a:e2:d5:f3:8e:6f (3a:e2:d5:f3:8e:6f)
Internet Protocol Version 4, Src: 10.0.0.101 (10.0.0.101), Dst: 10.0.0.11 (10.0.0.11)
Transmission Control Protocol, Src Port: 3000 (3000), Dst Port: 51659 (51659), Seq: 2100, Ack: 80, Len: 165
[3 Reassembled TCP Segments (2264 bytes): #15(651), #16(1448), #22(165)]
Hypertext Transfer Protocol
Line-based text data: text/html
No. Time Source Destination Protocol Length Info
25 11:41:45.502736000 10.0.0.11 10.0.0.101 TCP 78 [TCP Dup ACK 21#1] 51659 > 3000 [ACK] Seq=80 Ack=652 Win=17536 Len=0 TSval=1953061 TSecr=10192019 SLE=2100 SRE=2265
Frame 25: 78 bytes on wire (624 bits), 78 bytes captured (624 bits) on interface 0
Ethernet II, Src: 3a:e2:d5:f3:8e:6f (3a:e2:d5:f3:8e:6f), Dst: 56:c8:52:17:31:67 (56:c8:52:17:31:67)
Internet Protocol Version 4, Src: 10.0.0.11 (10.0.0.11), Dst: 10.0.0.101 (10.0.0.101)
Transmission Control Protocol, Src Port: 51659 (51659), Dst Port: 3000 (3000), Seq: 80, Ack: 652, Len: 0
No. Time Source Destination Protocol Length Info
26 11:41:45.504245000 10.0.0.101 10.0.0.11 TCP 1514 [TCP Retransmission] 3000 > 51659 [ACK] Seq=652 Ack=80 Win=29056 Len=1448 TSval=10192032 TSecr=1953061[Reassembly error, protocol TCP: New fragment overlaps old data (retransmission?)]
Frame 26: 1514 bytes on wire (12112 bits), 1514 bytes captured (12112 bits) on interface 0
Ethernet II, Src: 56:c8:52:17:31:67 (56:c8:52:17:31:67), Dst: 3a:e2:d5:f3:8e:6f (3a:e2:d5:f3:8e:6f)
Internet Protocol Version 4, Src: 10.0.0.101 (10.0.0.101), Dst: 10.0.0.11 (10.0.0.11)
Transmission Control Protocol, Src Port: 3000 (3000), Dst Port: 51659 (51659), Seq: 652, Ack: 80, Len: 1448
[Reassembly error, protocol TCP: New fragment overlaps old data (retransmission?)]
No. Time Source Destination Protocol Length Info
33 11:41:45.711324000 10.0.0.101 10.0.0.11 TCP 1514 [TCP Retransmission] 3000 > 51659 [ACK] Seq=652 Ack=80 Win=29056 Len=1448 TSval=10192239 TSecr=1953061[Reassembly error, protocol TCP: New fragment overlaps old data (retransmission?)]
Frame 33: 1514 bytes on wire (12112 bits), 1514 bytes captured (12112 bits) on interface 0
Ethernet II, Src: 56:c8:52:17:31:67 (56:c8:52:17:31:67), Dst: 3a:e2:d5:f3:8e:6f (3a:e2:d5:f3:8e:6f)
Internet Protocol Version 4, Src: 10.0.0.101 (10.0.0.101), Dst: 10.0.0.11 (10.0.0.11)
Transmission Control Protocol, Src Port: 3000 (3000), Dst Port: 51659 (51659), Seq: 652, Ack: 80, Len: 1448
[Reassembly error, protocol TCP: New fragment overlaps old data (retransmission?)]
Ruby代码：
def run
stop = false
Signal.trap("SIGINT") {
stop=true
}
tap.up
#binding.pry
pids = []
begin
# tap => zmq_pub
pids << Thread.new do
while !stop do
read_and_pub
end
end
# zmq_sub => tap
pids << Thread.new do
while !stop do
sub_and_write
end
end
rescue
stop=true
end
pids.each { |pid| pid.join }
tap.down
tap.close
self.tap = nil
zmq_pub.close
zmq_sub.close
zmq_ctx.terminate
end # run
def read_and_pub
selected = IO.select([tap.to_io],nil,nil,1)
if !selected.nil? and !selected[0].nil? and selected[0].length>0 then
msg = tap.to_io.sysread(tap.mtu)
if !msg.nil? && msg.length > 0 then
sent = zmq_pub.send_string(msg)
if sent != msg.length
puts "**** published #{sent}/#{msg.length} ****"
end
print_packet msg, tap
else
puts "IO.select returned #{selected} but msg is #{msg}"
end
end
end
def sub_and_write
msg = ''
zmq_sub.recv_string msg
if !msg.nil? && msg.length > 0 then
sent = tap.to_io.syswrite(msg)
if sent != msg.length
puts "**** wrote #{sent}/#{msg.length} ****"
end
print_packet msg, zmq_sub
end
end
问题在这里：tap.to_io.sysread(tap.mtu)。似乎 tap.mtu 不一定是 sysread 将接收的最大字节数，未读字节似乎从 tap 接口中被丢弃。我将代码更改为 tap.to_io.sysread(10000) 并且 http 和 ssh 按预期工作。我收到的最大帧是1514
我已经创建了一个 tap0 设备（IP 10.0.0.101），并且正在使用 zeromq 的 pgm pub/sub（例如 pgm://192.168.100.2;234.5.6.7:5555）从点击 zmq 订阅者，反之亦然。这个想法是使用 pgm 创建一个虚拟网络。我在网络上有 2 个 Tap 主机：10.0.0.101、10.0.0.11。他们在 192.168.106.126、192.168.106.55 也有物理以太网适配器。
'问题是 ping 有效，但 http 和 ssh 协议无效。
Wireshark 显示成功的 TCP 启动序列，但随后我开始看到重复的 ACK、重传，并且 curl 和 ssh 挂起一段时间并最终出错。
下面是 Wireshark 的一个片段，后面是大部分（希望如此）相关的 ruby 源代码。这是使用 rb_tuntap 和 ffi-rzmq 宝石。
No. Time Source Destination Protocol Length Info
7 11:41:45.464867000 10.0.0.11 10.0.0.101 TCP 74 51659 > 3000 [SYN] Seq=0 Win=14600 Len=0 MSS=1460 SACK_PERM=1 TSval=1953042 TSecr=0 WS=64
Frame 7: 74 bytes on wire (592 bits), 74 bytes captured (592 bits) on interface 0
Ethernet II, Src: 3a:e2:d5:f3:8e:6f (3a:e2:d5:f3:8e:6f), Dst: 56:c8:52:17:31:67 (56:c8:52:17:31:67)
Internet Protocol Version 4, Src: 10.0.0.11 (10.0.0.11), Dst: 10.0.0.101 (10.0.0.101)
Transmission Control Protocol, Src Port: 51659 (51659), Dst Port: 3000 (3000), Seq: 0, Len: 0
No. Time Source Destination Protocol Length Info
8 11:41:45.464956000 10.0.0.101 10.0.0.11 TCP 74 3000 > 51659 [SYN, ACK] Seq=0 Ack=1 Win=28960 Len=0 MSS=1460 SACK_PERM=1 TSval=10191992 TSecr=1953042 WS=128
Frame 8: 74 bytes on wire (592 bits), 74 bytes captured (592 bits) on interface 0
Ethernet II, Src: 56:c8:52:17:31:67 (56:c8:52:17:31:67), Dst: 3a:e2:d5:f3:8e:6f (3a:e2:d5:f3:8e:6f)
Internet Protocol Version 4, Src: 10.0.0.101 (10.0.0.101), Dst: 10.0.0.11 (10.0.0.11)
Transmission Control Protocol, Src Port: 3000 (3000), Dst Port: 51659 (51659), Seq: 0, Ack: 1, Len: 0
No. Time Source Destination Protocol Length Info
11 11:41:45.473101000 10.0.0.11 10.0.0.101 TCP 66 51659 > 3000 [ACK] Seq=1 Ack=1 Win=14656 Len=0 TSval=1953044 TSecr=10191992
Frame 11: 66 bytes on wire (528 bits), 66 bytes captured (528 bits) on interface 0
Ethernet II, Src: 3a:e2:d5:f3:8e:6f (3a:e2:d5:f3:8e:6f), Dst: 56:c8:52:17:31:67 (56:c8:52:17:31:67)
Internet Protocol Version 4, Src: 10.0.0.11 (10.0.0.11), Dst: 10.0.0.101 (10.0.0.101)
Transmission Control Protocol, Src Port: 51659 (51659), Dst Port: 3000 (3000), Seq: 1, Ack: 1, Len: 0
No. Time Source Destination Protocol Length Info
12 11:41:45.473429000 10.0.0.11 10.0.0.101 HTTP 145 GET / HTTP/1.1
Frame 12: 145 bytes on wire (1160 bits), 145 bytes captured (1160 bits) on interface 0
Ethernet II, Src: 3a:e2:d5:f3:8e:6f (3a:e2:d5:f3:8e:6f), Dst: 56:c8:52:17:31:67 (56:c8:52:17:31:67)
Internet Protocol Version 4, Src: 10.0.0.11 (10.0.0.11), Dst: 10.0.0.101 (10.0.0.101)
Transmission Control Protocol, Src Port: 51659 (51659), Dst Port: 3000 (3000), Seq: 1, Ack: 1, Len: 79
Hypertext Transfer Protocol
No. Time Source Destination Protocol Length Info
13 11:41:45.473460000 10.0.0.101 10.0.0.11 TCP 66 3000 > 51659 [ACK] Seq=1 Ack=80 Win=29056 Len=0 TSval=10192001 TSecr=1953046
Frame 13: 66 bytes on wire (528 bits), 66 bytes captured (528 bits) on interface 0
Ethernet II, Src: 56:c8:52:17:31:67 (56:c8:52:17:31:67), Dst: 3a:e2:d5:f3:8e:6f (3a:e2:d5:f3:8e:6f)
Internet Protocol Version 4, Src: 10.0.0.101 (10.0.0.101), Dst: 10.0.0.11 (10.0.0.11)
Transmission Control Protocol, Src Port: 3000 (3000), Dst Port: 51659 (51659), Seq: 1, Ack: 80, Len: 0
No. Time Source Destination Protocol Length Info
15 11:41:45.491555000 10.0.0.101 10.0.0.11 TCP 717 [TCP segment of a reassembled PDU]
Frame 15: 717 bytes on wire (5736 bits), 717 bytes captured (5736 bits) on interface 0
Ethernet II, Src: 56:c8:52:17:31:67 (56:c8:52:17:31:67), Dst: 3a:e2:d5:f3:8e:6f (3a:e2:d5:f3:8e:6f)
Internet Protocol Version 4, Src: 10.0.0.101 (10.0.0.101), Dst: 10.0.0.11 (10.0.0.11)
Transmission Control Protocol, Src Port: 3000 (3000), Dst Port: 51659 (51659), Seq: 1, Ack: 80, Len: 651
No. Time Source Destination Protocol Length Info
16 11:41:45.491599000 10.0.0.101 10.0.0.11 TCP 1514 [TCP segment of a reassembled PDU]
Frame 16: 1514 bytes on wire (12112 bits), 1514 bytes captured (12112 bits) on interface 0
Ethernet II, Src: 56:c8:52:17:31:67 (56:c8:52:17:31:67), Dst: 3a:e2:d5:f3:8e:6f (3a:e2:d5:f3:8e:6f)
Internet Protocol Version 4, Src: 10.0.0.101 (10.0.0.101), Dst: 10.0.0.11 (10.0.0.11)
Transmission Control Protocol, Src Port: 3000 (3000), Dst Port: 51659 (51659), Seq: 652, Ack: 80, Len: 1448
No. Time Source Destination Protocol Length Info
21 11:41:45.496998000 10.0.0.11 10.0.0.101 TCP 66 51659 > 3000 [ACK] Seq=80 Ack=652 Win=17536 Len=0 TSval=1953058 TSecr=10192019
Frame 21: 66 bytes on wire (528 bits), 66 bytes captured (528 bits) on interface 0
Ethernet II, Src: 3a:e2:d5:f3:8e:6f (3a:e2:d5:f3:8e:6f), Dst: 56:c8:52:17:31:67 (56:c8:52:17:31:67)
Internet Protocol Version 4, Src: 10.0.0.11 (10.0.0.11), Dst: 10.0.0.101 (10.0.0.101)
Transmission Control Protocol, Src Port: 51659 (51659), Dst Port: 3000 (3000), Seq: 80, Ack: 652, Len: 0
No. Time Source Destination Protocol Length Info
22 11:41:45.497026000 10.0.0.101 10.0.0.11 HTTP 231 HTTP/1.1 200 OK (text/html)
Frame 22: 231 bytes on wire (1848 bits), 231 bytes captured (1848 bits) on interface 0
Ethernet II, Src: 56:c8:52:17:31:67 (56:c8:52:17:31:67), Dst: 3a:e2:d5:f3:8e:6f (3a:e2:d5:f3:8e:6f)
Internet Protocol Version 4, Src: 10.0.0.101 (10.0.0.101), Dst: 10.0.0.11 (10.0.0.11)
Transmission Control Protocol, Src Port: 3000 (3000), Dst Port: 51659 (51659), Seq: 2100, Ack: 80, Len: 165
[3 Reassembled TCP Segments (2264 bytes): #15(651), #16(1448), #22(165)]
Hypertext Transfer Protocol
Line-based text data: text/html
No. Time Source Destination Protocol Length Info
25 11:41:45.502736000 10.0.0.11 10.0.0.101 TCP 78 [TCP Dup ACK 21#1] 51659 > 3000 [ACK] Seq=80 Ack=652 Win=17536 Len=0 TSval=1953061 TSecr=10192019 SLE=2100 SRE=2265
Frame 25: 78 bytes on wire (624 bits), 78 bytes captured (624 bits) on interface 0
Ethernet II, Src: 3a:e2:d5:f3:8e:6f (3a:e2:d5:f3:8e:6f), Dst: 56:c8:52:17:31:67 (56:c8:52:17:31:67)
Internet Protocol Version 4, Src: 10.0.0.11 (10.0.0.11), Dst: 10.0.0.101 (10.0.0.101)
Transmission Control Protocol, Src Port: 51659 (51659), Dst Port: 3000 (3000), Seq: 80, Ack: 652, Len: 0
No. Time Source Destination Protocol Length Info
26 11:41:45.504245000 10.0.0.101 10.0.0.11 TCP 1514 [TCP Retransmission] 3000 > 51659 [ACK] Seq=652 Ack=80 Win=29056 Len=1448 TSval=10192032 TSecr=1953061[Reassembly error, protocol TCP: New fragment overlaps old data (retransmission?)]
Frame 26: 1514 bytes on wire (12112 bits), 1514 bytes captured (12112 bits) on interface 0
Ethernet II, Src: 56:c8:52:17:31:67 (56:c8:52:17:31:67), Dst: 3a:e2:d5:f3:8e:6f (3a:e2:d5:f3:8e:6f)
Internet Protocol Version 4, Src: 10.0.0.101 (10.0.0.101), Dst: 10.0.0.11 (10.0.0.11)
Transmission Control Protocol, Src Port: 3000 (3000), Dst Port: 51659 (51659), Seq: 652, Ack: 80, Len: 1448
[Reassembly error, protocol TCP: New fragment overlaps old data (retransmission?)]
No. Time Source Destination Protocol Length Info
33 11:41:45.711324000 10.0.0.101 10.0.0.11 TCP 1514 [TCP Retransmission] 3000 > 51659 [ACK] Seq=652 Ack=80 Win=29056 Len=1448 TSval=10192239 TSecr=1953061[Reassembly error, protocol TCP: New fragment overlaps old data (retransmission?)]
Frame 33: 1514 bytes on wire (12112 bits), 1514 bytes captured (12112 bits) on interface 0
Ethernet II, Src: 56:c8:52:17:31:67 (56:c8:52:17:31:67), Dst: 3a:e2:d5:f3:8e:6f (3a:e2:d5:f3:8e:6f)
Internet Protocol Version 4, Src: 10.0.0.101 (10.0.0.101), Dst: 10.0.0.11 (10.0.0.11)
Transmission Control Protocol, Src Port: 3000 (3000), Dst Port: 51659 (51659), Seq: 652, Ack: 80, Len: 1448
[Reassembly error, protocol TCP: New fragment overlaps old data (retransmission?)]
Ruby代码：
def run
stop = false
Signal.trap("SIGINT") {
stop=true
}
tap.up
#binding.pry
pids = []
begin
# tap => zmq_pub
pids << Thread.new do
while !stop do
read_and_pub
end
end
# zmq_sub => tap
pids << Thread.new do
while !stop do
sub_and_write
end
end
rescue
stop=true
end
pids.each { |pid| pid.join }
tap.down
tap.close
self.tap = nil
zmq_pub.close
zmq_sub.close
zmq_ctx.terminate
end # run
def read_and_pub
selected = IO.select([tap.to_io],nil,nil,1)
if !selected.nil? and !selected[0].nil? and selected[0].length>0 then
msg = tap.to_io.sysread(tap.mtu)
if !msg.nil? && msg.length > 0 then
sent = zmq_pub.send_string(msg)
if sent != msg.length
puts "**** published #{sent}/#{msg.length} ****"
end
print_packet msg, tap
else
puts "IO.select returned #{selected} but msg is #{msg}"
end
end
end
def sub_and_write
msg = ''
zmq_sub.recv_string msg
if !msg.nil? && msg.length > 0 then
sent = tap.to_io.syswrite(msg)
if sent != msg.length
puts "**** wrote #{sent}/#{msg.length} ****"
end
print_packet msg, zmq_sub
end
end
问题在这里：tap.to_io.sysread(tap.mtu)。似乎 tap.mtu 不一定是 sysread 将接收的最大字节数，未读字节似乎从 tap 接口中被丢弃。我将代码更改为 tap.to_io.sysread(10000) 并且 http 和 ssh 按预期工作。我收到的最大帧是1514