Tag Archives: socket

Linux kernel hacking – support SO_PEERCRED for local TCP socket connections

In my old post (https://davejingtian.org/2015/02/17/retrieve-pid-from-the-packet-in-unix-domain-socket-a-complete-use-case-for-recvmsgsendmsg/), we talked about how to retrieve the peer PID from Unix domain socket using struct ucred. A more smart way to do this is using getsockopt() syscall with option SO_PEERCRED directly. As you expected (or … Continue reading

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Retrieve PID from the packet in Unix domain socket – a complete use case for recvmsg()/sendmsg()

The original question was how to retrieve the PID of the packet (sender) in the Unix domain socket. As titled, the answer is recvmsg()/sendmsg(). However, the most useful information I could find online is Michael’s man7.org. People keep talking about … Continue reading

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Python Hacking – urlopen timeout issue

Recent playing with Python urllib2 reveals an interesting fact that the timeout parameter of urlopen() does not work sometimes. The interesting issue has successfully pushed me deep into the Python source code for debugging. The final debugging, without surprise, shows … Continue reading

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bind() error 0x63 – Cannot assign requested address

Recently encountered a bind() error 0x63 – cannot assign requested address. After some effort on debugging, I list 2 possibilities here for reference when handling such this error code from bind().  Generally, if it is related with bad socket close/cleanup, … Continue reading

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socket (buffer) overflow detection tool – sodt

Name: sodt (套接字缓存溢出探测器) Language: KSH Destination: Detect socket buffer overflow for certain process real-timely Orignal Intention: Confirm messages lost caused by socket buffer overflow Version: 0.1 Supported Protocol: UDP/TCP/SCTP Supported OS: Linux/FreeBSD Note: ‘root’ permission is preferred to avoid OS … Continue reading

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