<html> <head> <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"> <style type="text/css" style="display:none;"></style> </head> <body dir="ltr"> <div id="divtagdefaultwrapper" style="font-size:12pt;color:#000000;font-family:Calibri,Helvetica,sans-serif;" dir="ltr"> <div dir="ltr" style="font-size: 12pt; color: rgb(0, 0, 0); font-family: Calibri, Helvetica, sans-serif, "EmojiFont", "Apple Color Emoji", "Segoe UI Emoji", NotoColorEmoji, "Segoe UI Symbol", "Android Emoji", EmojiSymbols;"> <div><span style="font-family: Arial, Helvetica, sans-serif;">Hi systemd-devel,</span><br> <span style="font-family: Arial, Helvetica, sans-serif;"></span><br> <span style="font-family: Arial, Helvetica, sans-serif;"></span></div> <span style="font-family: Arial, Helvetica, sans-serif;">Sorry to bug you with another user question.<br> </span></div> <div dir="ltr" style="font-size: 12pt; color: rgb(0, 0, 0); font-family: Calibri, Helvetica, sans-serif, "EmojiFont", "Apple Color Emoji", "Segoe UI Emoji", NotoColorEmoji, "Segoe UI Symbol", "Android Emoji", EmojiSymbols;"> <span style="font-family: Arial, Helvetica, sans-serif;"><br> </span></div> <div dir="ltr" style="font-size: 12pt; color: rgb(0, 0, 0); font-family: Calibri, Helvetica, sans-serif, "EmojiFont", "Apple Color Emoji", "Segoe UI Emoji", NotoColorEmoji, "Segoe UI Symbol", "Android Emoji", EmojiSymbols;"> <span style="font-family: Arial, Helvetica, sans-serif;">I have a socket activated daemon, call it mydaemon, and I have trouble finding out who connects to it.</span> <p><span style="font-family: Arial, Helvetica, sans-serif;"><br> </span></p> <p><span style="font-family: Arial, Helvetica, sans-serif;">mydaemon.socket contains:</span></p> <p><span style="font-family: Arial, Helvetica, sans-serif;"><br> </span></p> <div><span style="font-family: "Courier New", monospace;"><span style="font-family: "Courier New", monospace;"> </span>[Socket]</span><br> <span style="font-family: "Courier New", monospace;"> ListenStream=9999</span><br> </div> <div><br> </div> <div><span style="font-family: Arial, Helvetica, sans-serif;">When I connect using IPv4 using</span></div> <div><span style="font-family: Arial, Helvetica, sans-serif;"><br> </span></div> <div><span style="font-family: "Courier New", monospace;"> nc -4 localhost 9999<br> </span></div> <div><span style="font-family: Arial, Helvetica, sans-serif;"><br> </span></div> <div><span style="font-family: Arial, Helvetica, sans-serif;">then mydaemon does</span></div> <div><span style="font-family: Arial, Helvetica, sans-serif;"><br> </span></div> <div><span style="font-family: "Courier New", monospace;"> sockaddr_in6 peer;</span><br> <span style="font-family: "Courier New", monospace;"> socklen_t peer_size=sizeof(peer);</span><br> <span style="font-family: "Courier New", monospace;"> accept(3,(struct sockaddr *)&peer,sizeof(peer))</span><br> </div> <span style="font-family: Arial, Helvetica, sans-serif;"><span style="font-family: Arial, Helvetica, sans-serif;"><br> </span></span> <p><span style="font-family: Arial, Helvetica, sans-serif;"><span style="font-family: Arial, Helvetica, sans-serif;">Afterwards, </span><span style="font-family: Arial, Helvetica, sans-serif;">peer.</span></span><span style="font-family: Arial, Helvetica, sans-serif;"><span style="font-family: Arial, Helvetica, sans-serif;">sin6_family</span><span style="font-family: Arial, Helvetica, sans-serif;"><span style="font-family: Arial, Helvetica, sans-serif;"> is </span><span style="font-family: Arial, Helvetica, sans-serif;">AF_INET6</span><span style="font-family: Arial, Helvetica, sans-serif;"> and peer.<span>sin6_addr contains some gibberish like <span>a00:e5ae::</span></span></span></span></span></p> <p><span style="font-family: Arial, Helvetica, sans-serif;"><span style="font-family: Arial, Helvetica, sans-serif;"><span style="font-family: Arial, Helvetica, sans-serif;"><span><span><br> </span></span></span></span></span></p> <p><span style="font-family: Arial, Helvetica, sans-serif;"><span style="font-family: Arial, Helvetica, sans-serif;"><span style="font-family: Arial, Helvetica, sans-serif;"><span><span>If I connect more than once, the gibberish changes from connection to connection.<br> </span></span></span></span></span></p> <p><span style="font-family: Arial, Helvetica, sans-serif;"><br> </span></p> <p><span style="font-family: Arial, Helvetica, sans-serif;">Something similar happens if I connect using IPv6.</span></p> <p><span style="font-family: Arial, Helvetica, sans-serif;"><br> </span></p> <p><span style="font-family: Arial, Helvetica, sans-serif;">If I change <span style="font-family: Arial, Helvetica, sans-serif;"> mydaemon.socket</span> to<br> </span></p> <p><span style="font-family: Arial, Helvetica, sans-serif;"></span></p> <p><span style="font-family: Arial, Helvetica, sans-serif;"><br> </span></p> <div><span style="font-family: "Courier New", monospace;"><span style="font-family: "Courier New", monospace;"> </span>[Socket]</span><br> <span style="font-family: "Courier New", monospace;"> ListenStream=0.0.0.0:9999</span><br> </div> <div><br> </div> <div><span style="font-family: Arial, Helvetica, sans-serif;">Then <span style="font-family: Arial, Helvetica, sans-serif;"><span style="font-family: Arial, Helvetica, sans-serif;"></span><span style="font-family: Arial, Helvetica, sans-serif;">peer.</span></span><span style="font-family: Arial, Helvetica, sans-serif;"><span style="font-family: Arial, Helvetica, sans-serif;">sin6_family</span><span style="font-family: Arial, Helvetica, sans-serif;"><span style="font-family: Arial, Helvetica, sans-serif;"> becomes </span><span style="font-family: Arial, Helvetica, sans-serif;">AF_INET as it should. But if peer is cast to struct sockaddr_in then peer.<span>sin_addr</span> still contains gibberish like <span>2.0.191.150 (I expected something like 127.0.0.1 or <span>192.168.0.99</span>).</span></span><span style="font-family: Arial, Helvetica, sans-serif;"></span></span></span> <div><span style="font-family: Arial, Helvetica, sans-serif;"><br> </span></div> <span style="font-family: "Courier New", monospace;"></span>When I connect from other machines, the peer address still is gibberish.</span></div> <div><span style="font-family: Arial, Helvetica, sans-serif;"><br> </span></div> <div><span style="font-family: Arial, Helvetica, sans-serif;">If mydaemon creates the listening socket, I can easily get the peer address.</span></div> <div><span style="font-family: Arial, Helvetica, sans-serif;"><br> </span></div> <div><span style="font-family: Arial, Helvetica, sans-serif;">I suspect that when systemd creates the listening socket then accept(3,...) returns a socket which is connected to a local socket created by systemd.</span></div> <div><span style="font-family: Arial, Helvetica, sans-serif;"><br> </span></div> <div><span style="font-family: Arial, Helvetica, sans-serif;">QUESTION: Is that suspicion correct? And if yes, is there are way to recover the address of the actually connecting peer?</span></div> <div><span style="font-family: Arial, Helvetica, sans-serif;"><br> </span></div> <div><span style="font-family: Arial, Helvetica, sans-serif;">Cheers,</span></div> <div><span style="font-family: Arial, Helvetica, sans-serif;">Klaus<br> </span></div> <div><span style="font-family: Arial, Helvetica, sans-serif;"><br> </span></div> <span style="font-family: "Courier New", monospace;"></span></div> </div> </body> </html>