Linux socket timestamp. +0000 (UTC).

Linux socket timestamp. SO_TIMESTAMP is defined as SO_TIMESTAMP_NEW or SO_TIMESTAMP_OLD based on the architecture type and time_t representation of libc Linux PTP The Linux PTP project is an implementation of the Precision Time Protocol according to IEEE-1588, for Linux. I'm trying to get the timestamp a TCP message arrives on the wire with at least microsecond precision. Linux provides a socket control message to add timestamp ancillary data to the the socket, which can be controlled by 2 different socket options SO_TIMESTAMP and SO_TIMESTAMPNS, using setsockopt (2). Name setsockopt - set the socket options Synopsis #include <sys/socket. 控制接口 ¶ 用于接收网络包时间戳的接口包括 SO_TIMESTAMP 为每个传入数据包生成一个时间戳，该时间戳以（不一定是单调的）系统时间表示。通过 recvmsg () 在控制消息中以微秒分辨率报告时间戳。SO_TIMESTAMP 根据架构类型和 libc 的 time_t 表示定义为 SO_TIMESTAMP_NEW 或 SO_TIMESTAMP_OLD。对于 SO Browse the source of glibc glibc-2 using KDAB Codebrowser which provides IDE like features for browsing C, C++, Rust & Dart code in your browser Elixir Cross Referencer - source code of Glibc glibc-2. 10 最近看内核参数tcp_tw_recycle(该参数在内核 4. An IP socket is created using socket (2): socket (AF_INET 时间戳 ¶ 1. 1 SO_TIMESTAMP (also SO_TIMESTAMP_OLD and SO_TIMESTAMP_NEW) ¶ This socket option enables timestamping of datagrams on the reception path. ip contains a level 2 multicasting implementation conforming to RFC 1112. Not reloaded on reload signal. , VRFs) with connected sockets derived from the listen socket to be bound to the L3 domain in which the packets originated. The programming interface is BSD-sockets compatible. For writing rarp and other similar things on the user level. Information about May 8, 2010 · 1. 0, the only way to get a packet socket was with the call: socket(AF_INET, SOCK_PACKET, protocol) This is still supported, but deprecated and strongly discouraged. Onload implements a microsecond resolution software timestamping mechanism, which +0000 (UTC). Thanks to Linux, UDP datagrams, and kernel timestamps: Lots of examples and stackoversflow entries later, and still c Oct 8, 2018 · In the TCP handshake, you may see an option called timestamps, shortly followed by scary-looking “TSval” and "TSecr" numbers. They use ktime_get_real. recvmsg(65535, 1024) ancdata [0] [2] is the hardware timestamp as a timespec (ulong, ulong). Just to check sock_get_timestamp is used in inet_ioctl in af_inet. Page generated on 2020-07-23 22:17 EST. But all the documentation and test coding are d Linux ICMP internally uses a raw socket to send ICMPs. Else it will be managed by the kernel. Reports the timestamp via recvmsg() in a control message in usec resolution. Howto can be found at: Mar 24, 2014 · SO_TIMESTAMP，一个Socket选项，在权威著作《Unix 网络编程》中未提及到，即使在google上也难找到其详细解释与用法。 然而在开源代码ptpv2d-rc1中用到了这个socket选项，那么它到底是用来做什么的呢。 Oct 27, 2025 · You can use hardware timestamps for received packets and for transmitted packets. The same is true for all early receive timestamp options. Nov 4, 2023 · Sockets provide the fundamental building blocks for networking in C programs. Linux ICMP internally uses a raw socket to send ICMPs. COLOPHON This page is part of release 5. Motivation / Why Using the Socket API ¶ There have been CAN implementations for Linux before SocketCAN so the question arises, why we have started another project. Only valid when the kernel was compiled with CONFIG_NET_L3_MASTER_DEV. SEE ALSO top ip(7), rdisc (8) RFC 792 for a description of the ICMP protocol. used only if the socket options SO_TIMESTAMP and SO_TIMESTAMPNS are not set on the socket. SOCK_RAW, socket. 01LTS Laptop (Kernel 3. The Python interface is a straightforward transliteration of the Unix system call and library interface for sockets to Python’s object-oriented style: the socket() function returns a socket object whose methods implement the various socket system calls. I set the following options on the socket with SO_TIMESTAMPING: Feb 26, 2015 · I am working in a project to get the receive and transmit time stamping from the NIC for TCP socket as mentioned in the document Linux timestamping. 4 内核版本3. Sep 22, 2024 · In this article, we will explore the process of timestamping IGMP packets and multicast data traffic using specific Linux socket options. Control Interfaces The interfaces for receiving network packages timestamps are: * SO_TIMESTAMP Generates a timestamp for each incoming packet in (not necessarily monotonic) system time. This is because SO_TIMESTAMP directs the kernel to make the timestamp available via recvmmsg ancillary data instead of via SIOCGSTAMP. Enabling this option allows a “global” listen socket to work across L3 master domains (e. Apr 1, 2020 · 2 It uses CLOCK_REALTIME. UDS is used to receive PTP management messages from localhost. DESCRIPTION The getsockopt () and setsockopt () system calls manipulate the options associated with a socket. But how does user application manage to get this hardware timestamp on=20 its side? linux specific way of getting packets at the dev level. Linux kernel source tree. 39: sysdeps/unix/sysv/linux/tst-socket-timestamp-compat. 0) SocketCAN PCAN USB Adapter using the mainline driver My question is: What kind of timestamp is generated when using recvmsg (HW timestamp, driver timestamp ,)? Is there a difference when using ioctl as I read in some internet forums? Thanks for your help! Sep 26, 2019 · 环境：centos7. In this case, the port must be set to 0, and the unix socket path must be given. htons(3)) s. getsockopt () and setsockopt () manipulate options for the socket referred to by the file descriptor sockfd. Otherwise, it returns the timestamp of the last packet that was received while SO_TIMESTAMP was not set, or it fails if no such packet has been received, (i. Generates timestamps on reception, transmission or both. COLOPHON top May 8, 2010 · Linux Kernel DocumentationBased on kernel version 5. Oct 27, 2025 · You can use hardware timestamps for received packets and for transmitted packets. Benefits of TCP Timestamps | Network troubleshooting and performance tuning | Red Hat Enterprise Linux | 10 | Red Hat DocumentationAdditionally, TCP Timestamps provide an alternative method to determine the age and order of a segment, and protect against wrapped sequence numbers. The protocol modules are grouped into protocol families such as AF_INET, AF_IPX, and AF_PACKET, and socket types such as SOCK_STREAM or SOCK_DGRAM. Enables child sockets to inherit the L3 master device index. -D Print timestamp (unix time + microseconds as in gettimeofday) before each line. less) socket SOCK_RAW raw socket SOCK_RDM reliably-delivered message SOCK_SEQPACKET sequential packet socket SOCK_DCCP Datagram Congestion Control Protocol socket SOCK_PACKET linux specific way of getting packets at the dev level. What is ICMP? The Internet Control Message Protocol (ICMP) is a network-layer protocol of the internet protocol suite (IP) used for sending Apr 28, 2021 · I figured the problem was related to tcp timestamps. e. My setup is as following: Ubuntu 14. This is where the setsockopt() function comes into play! In this comprehensive guide, we will deep […] NAME ¶ candump - manual page for candump 2023. Supports multiple timestamp sources, including hardware. COLOPHON top This page is part of the man-pages (Linux kernel and C library user-space interface documentation) project. Nov 16, 2017 · Linux, UDP datagrams, and kernel timestamps: Lots of examples and stackoversflow entries later, and still cannot get timestamps at all Mar 23, 2023 · Hi, I've recently switched back to arch linux. Apr 16, 2022 · @BlackBeans I don't think that gives me the accuracy/precision I'm interested in. AF_PACKET, socket. tcp_timestamps=0 Conversely, enabling timestamps on windows reproduces the same problem I observed on linux. This socket option enables timestamping of datagrams on the reception path. This ioctl should be used only if the socket option SO_TIMESTAMP is not set on the socket. The socket manual page (man 7 socket) describes how timestamps generated with SO_TIMESTAMP and SO_TIMESTAMPNS records can be retrieved. Not tested on DESCRIPTION top This is an implementation of the TCP protocol defined in RFC 793, RFC 1122 and RFC 2001 with the NewReno and SACK extensions. 硬件时间戳配置 2 Data Interfaces Timestamps are read using the ancillary data feature of recvmsg (). For more information on sockets, see socket (7). Sep 16, 2025 · The manual is available for the following releases of glibc: Mar 24, 2014 · SO_TIMESTAMP，一个Socket选项，在权威著作《Unix 网络编程》中未提及到，即使在google上也难找到其详细解释与用法。 然而在开源代码ptpv2d-rc1中用到了这个socket选项，那么它到底是用来做什么的呢。 Because the destination socket, if any, is not known early in the network stack, the feature has to be enabled for all packets. Minicom will then try to connect to this socket as a client. Variables static const int slack [] = { 0, 4, 8, 16, 32, slack_max_size } static bool support_64_timestamp static int srv static struct sockaddr_in srv_addr Previous message (by thread): [PATCH] Fix building tst-socket-timestamp-compat on older Linux Next message (by thread): [PATCH] Fix building tst-socket-timestamp-compat on older Linux Messages sorted by: [ date ] [ thread ] [ subject ] [ author ] More information about the Libc-alpha mailing list May 8, 2025 · This page provides a technical guide to programming with the SocketCAN API in Linux. The 64-bit timestamp returned by ICMP_TIMESTAMP is in milliseconds since the Epoch, 1970-01-01 00:00:00 +0000 (UTC). SO_TIMESTAMP is defined as SO_TIMESTAMP_NEW or SO_TIMESTAMP_OLD based on the architecture type and time_t representation of libc 1. Aug 5, 2020 · You know, that we are talking about microseconds? Linux is taking a Unix timestamp while in CAN interrupt with µs precision. Elixir Cross Referencer - source code of Glibc glibc-2. What am I doing wrong? Is there a better way of getting an accurate timestamp for an outgoing packet? Aug 6, 2024 · While reading here, here and here I see that on Linux systems you can request timestamps from received and transmitted packets by setting socket options. See man 3 cmsg for details of this interface. Does work on Linux but not on Mac OS X. Sep 28, 2023 · Given Linux is used and packet timestamping is enabled with SO_TIMESTAMPING for a TCP socket and we read now some data, what timestamp will be reported if the byte-stream which we read was merged out of multiple TCP packets (which each have different timestamps)? Oct 3, 2025 · If obtaining the hardware time stamp somehow fails, then the driver should not fall back to software time stamping. 1 SCM_TIMESTAMPING records These timestamps are returned in a control message This manual page describes the Linux networking socket layer user interface. For more details of using hardware packet timestamps when using OpenOnload see the Onload User Guide (UG1586). Socket-layer functions These functions are used by the user process to send or receive packets and to do other socket operations. So, for example, if you have an appropriate solarflare card, then setting the options will cause the card to timestamp. This raw socket may appear in netstat(8) output with a zero inode. SO_TIMESTAMP is defined as SO_TIMESTAMP_NEW or SO_TIMESTAMP_OLD based on the architecture type and time_t representation of libc Linux ICMP internally uses a raw socket to send ICMPs. I have followed this previously commented issue: Linux kernel UDP reception timestamp but after several tests I got some problems when trying to get hardware reception timestamps. This option may be specified multiple times. c NAME ¶ sock_tx_timestamp - checks whether the outgoing packet is to be time stamped SYNOPSIS ¶ void sock_tx_timestamp (const struct sock * sk, __u16 tsflags, __u8 * tx_flags); ARGUMENTS ¶ const struct sock * sk socket sending this packet __u16 tsflags timestamping flags to use Man page for ptp4l, an implementation of the Precision Time Protocol (PTP) according to IEEE standard 1588 for Linux. socket(socket. What are those values and how can you interpret them? Let’s dig. c. -C Call connect () syscall on socket creation. Otherwise, it returns the timestamp of the last packet that was received while SO_TIMESTAMP and SO_TIMESTAMPNS were not set, or it fails if no such packet has been. It sends standardized CANopen commands (CiA309-3) to gateway and prints the responses to stdout and stderr. Action and Management ID. Dec 18, 2020 · Linux kernel provides two socket options for retrieving software timestamps of incoming network packets: SO_TIMESTAMP and SO_TIMESTAMPING with SOF_TIMESTAMPING_RX_SOFTWARE | SOF_TIMESTAMPING_SOFTWARE flags. This type of sockets is used for capture network traffic with utilities like tcpdump, transmit network traffic, or any other that needs raw access to network interface. Aug 4, 2021 · Linux recvmsg () not getting a software timestamp from socket Asked 3 years, 10 months ago Modified 3 years, 10 months ago Viewed 1k times timestamp of an skb by itself and push it with the received CAN frame,=20 so that the application could get it using SO_TIMESTAMP socket option,=20 right? Now, this "hardware" timestamp is to be copied into "hwstamp" field of=20 the "skb_hwtstamps (skb)" area. From there I jumped to sock_enable_timestamp. The CAN socket API has been designed as similar as possible to the TCP/IP protocols to allow programmers, familiar with network programming, to easily learn how to use CAN sockets. DESCRIPTION top Linux implements the Internet Protocol, version 4, described in RFC 791 and RFC 1122. socket(7) Miscellaneous Information Manual socket(7) NAME top socket - Linux socket interface SYNOPSIS top #include <sys/socket. SocketCAN exposes CAN bus functionality through the standard BSD socket programming interface, allowing developers some time. Supports generating timestamps for stream sockets. Options may exist at multiple protocol levels; they are always present at the uppermost “socket” level. The rationale is that this would occur at a later time in the processing pipeline than other software time stamping and therefore could lead to unexpected deltas between time stamps. In linux, by default tcp_timestamp is enabled, in windows it's disabled. Provides a reliable implementation of PTP for Linux, and correctly uses the kernel interfaces for PHC and timestamping. -d Set the SO_DEBUG option on the socket being used. 控制接口 ¶ 用于接收网络包时间戳的接口包括 SO_TIMESTAMP 为每个传入数据包生成一个时间戳，该时间戳以（不一定是单调的）系统时间表示。通过 recvmsg () 在控制消息中以微秒分辨率报告时间戳。SO_TIMESTAMP 根据架构类型和 libc 的 time_t 表示定义为 SO_TIMESTAMP_NEW 或 SO_TIMESTAMP_OLD。对于 SO On systems that support Unix Domain Sockets, this option can also be used to create a Unix socket rather than opening a TCP socket. Anything is fair game. In this case, management messages is sent only localhost. For writing rarp and other similar The Linux implementation of this interface may differ (consult the corresponding Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux. 12 之后被移除），它用于快速回收处理TIME_WAIT状态的socket。搜索该参数相关的资料，发现同时启用该参数和tcp_timestamps后有可能在NAT环境下导致客户端始连接失败，抓包 Oct 9, 2010 · Is it possible to have netstat show the date/time the connection was established? Is this information even stored anywhere in Linux? Jul 31, 2012 · Unfortunately, recvmsg is always returning -1 when called on a raw socket (created with socket (PF_INET, SOCK_RAW, IPPROTO_RAW) and with SO_TIMESTAMP set to 1 with setsockopt). See socket (2) for more This chapter requires some knowledge about the internet protocol (IP) and it’s structure. We are going to manually create ICMP packets to ping a target host. As long as it cannot connect to the socket it stays 'offline'. Browse the source of glibc glibc-2 using KDAB Codebrowser which provides IDE like features for browsing C, C++, Rust & Dart code in your browser Aug 10, 2016 · As far as I understand, even if the hardware does not support it, there is at least the option to retrieve the socket timestamp (SO_TIMESTAMP) of the last received packet. 05 of the Linux man-pages project. Contribute to torvalds/linux development by creating an account on GitHub. Disabling tcp timestamps on linux, solves the problem: sysctl -w net. 7. A description of the project, The CAN socket API has been designed as similar as possible to the TCP/IP protocols to allow programmers, familiar with network programming, to easily learn how to use CAN sockets. , ioctl (2) returns -1 with errno set to ENOENT). Sep 8, 2022 · However: I am struggling with parameter syntax: how would add that overlay parameter when running in server mode. The BSD compatible sockets are the uniform interface between the user process and the network protocol stacks in the kernel. But right above that function is sock_get_timestamp and sock_get_timestampns. For more details of hardware packet timestamps when using the kernel driver see the Solarflare Server Adapter User Guide (SF-103837-CD). -e identifier Set the identification field of ECHO_REQUEST. When manipulating socket options the level at which the option resides and the name of the option must be specified. SEE ALSO ip (7), rdisc (8) RFC 792 for a description of the ICMP protocol. However, for sockets to work optimally, they need to be tailored to the specific requirements of the applications using them. Options may exist at multiple protocol levels; They are also only accepted from the old gateway defined in the routing table and the redirect routes are expired after some time. Essentially, this socket option is not used by Linux kernel. h> header defines the socket-level options available to setsockopt (). See also the mount_point option. c Chapter 13. (use CTRL-C to terminate candump) OPTIONS ¶ -t <type> (timestamp: (a)bsolute/ (d)elta/ (z)ero/ (A)bsolute w date) -H (read hardware timestamps instead of system timestamps) -c (increment color mode level) -i (binary output - may exceed 80 chars/line Send a message to localhost’s node Get values of CURRENT_DATA_SET Indicate to use Unix Domain Socket. Always use SO_TIMESTAMP_NEW DESCRIPTION This manual page describes the Linux networking socket layer user interface. Puff. An application program can use setsockopt () to allocate buffer space, control timeouts, or permit socket data broadcasts. TCP packet headers record the sequence number in a 32-bit field. It generates and checks a per-packet checksum Jun 17, 2015 · Hi, I am currently looking into SocketCAN with a focus on timestamps. Man page for ptp4l, an implementation of the Precision Time Protocol (PTP) according to IEEE standard 1588 for Linux. It also contains an IP router including a packet filter. 数据接口 四. SIOCSPGRP To use a UNIX socket for communication the device name must be prefixed with "unix#" following by the full path and the filename of the socket. On a 10 Gbps connection, the value of 1. # pmc –u –b 0 ‘GET CURRENT_DATA_SET’ -b specifies allowance number of boundary hops. They enable seamless communication between applications across networks. 10. Oct 5, 2018 · Linux - Networking This forum is for any issue related to networks or networking. So: SO_TIMESTAMP is mentioned in sock_setsockopt. Because the destination socket, if any, is not known early in the network stack, the feature has to be enabled for all packets. The msghdr. ipv4. This value helps each TCP stack to In Linux 2. netsh int tcp set global timestamps=enabled Digging a bit further, I saw that the tcp Jul 31, 2023 · Setting the SO_TIMESTAMP or SO_TIMESTAMPNS options using setsockopt () enables software timestamping on TCP or UDP sockets. msgcontrollen returned is 0, and CMSG_FIRSTHDR gives NULL. The main difference between the two methods is that SOCK_PACKET uses the old struct sockaddr_pkt to specify an interface, which doesn't provide physical-layer independence. As soon as the connection establishes, minicom goes 'online'. I am currently able to use SO_TIMESTAMPNS and Mar 26, 2021 · I'm trying to send the transmit timestamp of a packet to calculate the latency. The BSD compatible sockets are the uniform interface between the user process and the network protocol Feb 13, 2017 · Normally hardware that supports this functionality will see the socket option (SO_TIMESTAMPNS or SO_TIMESTAMP) and then will stamp the packets. 时间戳 ¶ 1. Routing, network cards, OSI, etc. Finally, I have been able to get the SO_TIMESTAMPNS value like this: SO_TIMESTAMPNS = 35 s = socket. I've come across an issue where requesting SO_TIMESTAMPING and doing recvmsg on a socket returns no timestamps. Request timestamps with SO_TIMESTAMP const int one = 1; setsockopt(fd, SOL_SOCKET, SO_TIMESTAMP, &one, sizeof(one)); Nov 9, 2012 · When reading from a (non-stream) socket in Linux, I can get the (hardware-generated) timestamp of the last received message via a ioctl (sock, SIOCGSTAMP, &tv). Functions such as cmesg (), recvmsg () and recvmmsg () can then recover timestamps for packets received at the socket. 2. This ioctl should be used only if the socket options SO_TIMESTAMP and SO_TIMESTAMPNS are not set on the socket. setsockopt(socket. Parameter types are somewhat higher-level than in the C interface: as with read() and write() operations on Python files, buffer allocation Apr 18, 2024 · 三. What is a TCP Timestamp? The timestamps option in TCP enables the endpoints to keep a current measurement of the roundtrip time (RTT) of the network between them. For interface details, see man 7 socket. Description APPLICATION USAGE top The setsockopt () function provides an application program with the means to control socket behavior. SOL_SOCKET, SO_TIMESTAMPNS, 1) raw_data, ancdata, flags, address = s. This raw socket may appear in netstat (8) output with a zero inode. h> int setsockopt (int socket, int level, int option_name, Packet MMAP ¶ Abstract ¶ This file documents the mmap () facility available with the PACKET socket interface. Otherwise, it returns the timestamp of the last packet that was received while SO_TIMESTAMP and SO_TIMESTAMPNS were not set, or it fails if no such packet has been received, (i. h> sockfd = socket(int socket_family, int socket_type, int protocol); DESCRIPTION top This manual page describes the Linux networking socket layer user interface. SIOCSPGRP Jun 14, 2017 · Solution I am able to get the software timestamp along with hardware timestamp using onload with solarflare NIC. If you skipped the previous chapter you can find a short recap on the IP protocol header here. Dec 18, 2020 · Linux内核提供了两个套接字选项，用于检索传入网络数据包的软件时间戳：SO_TIMESTAMP和带有SOF_TIMESTAMPING_RX_SOFTWARE | SOF_TIMESTAMPING_SOFTWARE标志的SO_TIMESTAMPING。将它们描述如下：SO_TIMESTAMP在(不一定是单调的)系统时间内为每个传入数据包生成时间戳。SO_TIMESTAMPING当数据进入内核时请求 Mar 16, 2016 · Note that SIOCGSTAMP and SO_TIMESTAMP are mutually exclusive - if you're going to use SIOCGSTAMP you should disable SO_TIMESTAMP (with enabled = 0). The <sys/socket. 16. Aug 12, 2025 · The process involves four main steps: Configure the NTP server’s IP address and port, and create a UDP socket Construct and send an NTP request packet via UDP Receive the response and extract the "Transmit Timestamp" from the NTP packet Convert the NTP time to UNIX time, then to a LabVIEW timestamp See setitimer (2) for a description of struct timeval. The protocol modules are grouped into protocol families like PF_INET, PF_IPX, PF_PACKET and socket types like SOCK_STREAM or SOCK_DGRAM. Still no idea how to get software timestamp alone. g. Maintained by Richard Cochran, who also maintains PTP support in Linux. 03-1 SYNOPSIS ¶ candump [options] <CAN interface>+ DESCRIPTION ¶ candump - dump CAN bus traffic. The 64-bit timestamp returned by ICMP_TIMESTAMP is in milliseconds since January 1, 1970. , ioctl(2) returns -1 with errno set to ENOENT). Dec 19, 2024 · Hardware Timestamps (Kernel/Onload) Applications can recover hardware timestamps for all received packets using the SO_TIMESTAMPING socket option. SIOCSPGRP Networking Base Types enum sock_type Socket types Constants SOCK_STREAM stream (connection) socket SOCK_DGRAM datagram (conn. Sep 28, 2023 · Given Linux is used and packet timestamping is enabled with SO_TIMESTAMPING for a TCP socket and we read now some data, what timestamp will be reported if the byte-stream which we read was merged out of multiple TCP packets (which each have different timestamps)? Mar 4, 2019 · Since I want to achieve the best performance I'm trying to compare software timestamping results with hardware timestamping ones. TCP guarantees that the data arrives in order and retransmits lost packets. To manipulate options at the socket level, level is specified CANopenLinux/cocomm directory contains a small command line program, which establishes socket connection with canopend (CANopen Linux commander device). It provides a reliable, stream-oriented, full-duplex connection between two sockets on top of ip (7), for both v4 and v6 versions. Always use SO_TIMESTAMP_NEW timestamp to always get timestamp in struct __kernel_sock_timeval format. g979w1vkd 2c fyze 8n tc ouex ducz 3twi8m 0rfp fw8wo1w