29 lines
1015 B
Plaintext
29 lines
1015 B
Plaintext
// SPDX-License-Identifier: GPL-2.0
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// Test what happens when client does not provide MD5 on SYN,
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// but then does on the ACK that completes the three-way handshake.
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`./defaults.sh`
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// Establish a connection.
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0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3
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+0 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
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+0 bind(3, ..., ...) = 0
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+0 listen(3, 1) = 0
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+0 < S 0:0(0) win 32792 <mss 1000,sackOK,nop,nop,nop,wscale 10>
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+0 > S. 0:0(0) ack 1 <mss 1460,nop,nop,sackOK,nop,wscale 8>
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// Ooh, weird: client provides MD5 option on the ACK:
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+.01 < . 1:1(0) ack 1 win 514 <md5 000102030405060708090a0b0c0d0e0f,nop,nop>
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+.01 < . 1:1(0) ack 1 win 514 <md5 000102030405060708090a0b0c0d0e0f,nop,nop>
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// The TCP listener refcount should be 2, but on buggy kernels it can be 0:
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+0 `grep " 0A " /proc/net/tcp /proc/net/tcp6 | grep ":1F90"`
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// Now here comes the legit ACK:
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+.01 < . 1:1(0) ack 1 win 514
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// Make sure the connection is OK:
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+0 accept(3, ..., ...) = 4
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+.01 write(4, ..., 1000) = 1000
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