Linux 为什么strace缺少网络系统调用？
当我在Linux 为什么strace缺少网络系统调用？,linux,dns,system-calls,strace,Linux,Dns,System Calls,Strace,当我在dig（strace-dig-google.com）上运行strace）时，不会像DNS查询那样出现sendto或recvfrom系统调用dig肯定在执行网络请求：我可以在Wireshark中看到查询strace正在捕获socket和close系统调用。完整跟踪可在上获得，但我粘贴了以下相关部分： futex(0x7f3e959bbe34, FUTEX_WAKE_PRIVATE, 2147483647) = 0 futex(0x7f3e959bbf80, FUTEX_WAKE_PRIVAT
digstrace-dig-google.comstracesendtorecvfromdigsocketclosefutex(0x7f3e959bbe34, FUTEX_WAKE_PRIVATE, 2147483647) = 0
futex(0x7f3e959bbf80, FUTEX_WAKE_PRIVATE, 2147483647) = 0
futex(0x7f3e963f9290, FUTEX_WAKE_PRIVATE, 2147483647) = 0
socket(PF_INET, SOCK_STREAM, IPPROTO_IP) = 3
close(3) = 0
socket(PF_INET6, SOCK_STREAM, IPPROTO_IP) = 3
getsockname(3, {sa_family=AF_INET6, sin6_port=htons(0), inet_pton(AF_INET6, "::", &sin6_addr), sin6_flowinfo=0, sin6_scope_id=0}, [28]) = 0
close(3) = 0
socket(PF_LOCAL, SOCK_STREAM, 0) = 3
close(3) = 0
futex(0x7f3e959bc3ac, FUTEX_WAKE_PRIVATE, 2147483647) = 0
futex(0x7f3e959bbf08, FUTEX_WAKE_PRIVATE, 2147483647) = 0
mmap(NULL, 266240, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f3e965c8000
mmap(NULL, 8392704, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS|MAP_STACK, -1, 0) = 0x7f3e9028f000
mprotect(0x7f3e9028f000, 4096, PROT_NONE) = 0
clone(child_stack=0x7f3e90a8efb0, flags=CLONE_VM|CLONE_FS|CLONE_FILES|CLONE_SIGHAND|CLONE_THREAD|CLONE_SYSVSEM|CLONE_SETTLS|CLONE_PARENT_SETTID|CLONE_CHILD_CLEARTID, parent_tidptr=0x7f3e90a8f9d0, tls=0x7f3e90a8f700, child_tidptr=0x7f3e90a8f9d0) = 3083
mmap(NULL, 8392704, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS|MAP_STACK, -1, 0) = 0x7f3e8fa8e000
mprotect(0x7f3e8fa8e000, 4096, PROT_NONE) = 0
clone(child_stack=0x7f3e9028dfb0, flags=CLONE_VM|CLONE_FS|CLONE_FILES|CLONE_SIGHAND|CLONE_THREAD|CLONE_SYSVSEM|CLONE_SETTLS|CLONE_PARENT_SETTID|CLONE_CHILD_CLEARTID, parent_tidptr=0x7f3e9028e9d0, tls=0x7f3e9028e700, child_tidptr=0x7f3e9028e9d0) = 3084
brk(0x55fd6e9cd000) = 0x55fd6e9cd000
pipe([3, 4]) = 0
fcntl(3, F_GETFL) = 0 (flags O_RDONLY)
fcntl(3, F_SETFL, O_RDONLY|O_NONBLOCK) = 0
epoll_create(64) = 5
epoll_ctl(5, EPOLL_CTL_ADD, 3, {EPOLLIN, {u32=3, u64=3}}) = 0
mmap(NULL, 8392704, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS|MAP_STACK, -1, 0) = 0x7f3e8f28d000
mprotect(0x7f3e8f28d000, 4096, PROT_NONE) = 0
clone(child_stack=0x7f3e8fa8cfb0, flags=CLONE_VM|CLONE_FS|CLONE_FILES|CLONE_SIGHAND|CLONE_THREAD|CLONE_SYSVSEM|CLONE_SETTLS|CLONE_PARENT_SETTID|CLONE_CHILD_CLEARTID, parent_tidptr=0x7f3e8fa8d9d0, tls=0x7f3e8fa8d700, child_tidptr=0x7f3e8fa8d9d0) = 3085
open("/usr/share/locale/en_US.UTF-8/libdst.cat", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale/en_US.UTF-8/LC_MESSAGES/libdst.cat", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale/en/libdst.cat", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale/en/LC_MESSAGES/libdst.cat", O_RDONLY) = -1 ENOENT (No such file or directory)
futex(0x7f3e963f9b20, FUTEX_WAKE_PRIVATE, 2147483647) = 0
futex(0x7f3e963f9b24, FUTEX_WAKE_PRIVATE, 2147483647) = 0
brk(0x55fd6e9ee000) = 0x55fd6e9ee000
open("/usr/lib/ssl/openssl.cnf", O_RDONLY) = 6
fstat(6, {st_mode=S_IFREG|0644, st_size=10835, ...}) = 0
read(6, "#\n# OpenSSL example configuratio"..., 4096) = 4096
read(6, "Netscape crash on BMPStrings or "..., 4096) = 4096
read(6, " this to avoid interpreting an e"..., 4096) = 2643
read(6, "", 4096) = 0
close(6) = 0
futex(0x7f3e94c480a8, FUTEX_WAKE_PRIVATE, 2147483647) = 0
open("/usr/lib/x86_64-linux-gnu/openssl-1.0.0/engines/libgost.so", O_RDONLY|O_CLOEXEC) = 6
read(6, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\220T\0\0\0\0\0\0"..., 832) = 832
fstat(6, {st_mode=S_IFREG|0644, st_size=93280, ...}) = 0
mmap(NULL, 2188320, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 6, 0) = 0x7f3e8f076000
mprotect(0x7f3e8f08b000, 2093056, PROT_NONE) = 0
mmap(0x7f3e8f28a000, 12288, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 6, 0x14000) = 0x7f3e8f28a000
close(6) = 0
mprotect(0x7f3e8f28a000, 4096, PROT_READ) = 0
open("/home/ubuntu-user/.digrc", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/etc/resolv.conf", O_RDONLY) = 6
fstat(6, {st_mode=S_IFREG|0644, st_size=208, ...}) = 0
read(6, "# Dynamic resolv.conf(5) file fo"..., 4096) = 208
read(6, "", 4096) = 0
close(6) = 0
getppid() = 3080
rt_sigaction(SIGHUP, {0x7f3e957899e0, ~[RTMIN RT_1], SA_RESTORER, 0x7f3e9553f390}, NULL, 8) = 0
rt_sigsuspend([], 8) = ? ERESTARTNOHAND (To be restarted if no handler)
--- SIGTERM {si_signo=SIGTERM, si_code=SI_TKILL, si_pid=3082, si_uid=1000} ---
rt_sigreturn({mask=[HUP INT TERM]}) = -1 EINTR (Interrupted system call)
futex(0x55fd6df085a0, FUTEX_WAIT_PRIVATE, 2, NULL) = 0
futex(0x55fd6df085a0, FUTEX_WAKE_PRIVATE, 1) = 0
futex(0x7f3e90a8f9d0, FUTEX_WAIT, 3083, NULL) = 0
write(4, "\0\0\0\0\377\377\377\377", 8) = 8
epoll_ctl(5, EPOLL_CTL_DEL, 3, 0x7fff8ed49d10) = 0
close(5) = 0
close(3) = 0
close(4) = 0
futex(0x7f3e965cf07c, FUTEX_WAKE_OP_PRIVATE, 1, 1, 0x7f3e965cf078, {FUTEX_OP_SET, 0, FUTEX_OP_CMP_GT, 1}) = 1
futex(0x7f3e965cf028, FUTEX_WAKE_PRIVATE, 1) = 1
munmap(0x7f3e8f076000, 2188320) = 0
munmap(0x7f3e965c8000, 266240) = 0
write(1, "\n; <<>> DiG 9.10.3-P4-Ubuntu <<>"..., 484) = 484
exit_group(0) = ?
+++ exited with 0 +++
futex（0x7f3e959bbe34，futex_WAKE_PRIVATE，2147483647）=0
futex（0x7f3e959bbf80，futex_WAKE_PRIVATE，2147483647）=0
futex（0x7f3e963f9290，futex_WAKE_PRIVATE，2147483647）=0
套接字（PF_INET、SOCK_STREAM、IPPROTO_IP）=3
关闭（3）=0
插座（PF_INET6、插座流、IP协议）=3
getsockname（3，{sa_family=AF_INET6，sin6_port=htons（0），inet_pton（AF_INET6，“：：”，&sin6_addr），sin6_flowinfo=0，sin6_scope_id=0}，[28]）=0
关闭（3）=0
套接字（PF_本地，SOCK_流，0）=3
关闭（3）=0
futex（0x7f3e959bc3ac，futex_WAKE_PRIVATE，2147483647）=0
futex（0x7f3e959bbf08，futex_WAKE_PRIVATE，2147483647）=0
mmap（NULL，266240，保护读写，映射私有，映射匿名，-1，0）=0x7f3e965c8000
mmap（NULL，8392704，保护读写，映射私有，映射匿名，映射堆栈，-1，0）=0x7f3e9028f000
mprotect（0x7f3e9028f000，4096，无保护）=0
克隆（child_stack=0x7f3e90a8efb0，flags=clone_VM | clone_FS | clone_FILES | clone_SIGHAND | clone_THREAD | clone_SYSVSEM | clone| clone|SETTID | clone| child | CLEARTID | PARENT | tidptr
mmap（NULL，8392704，保护读取，保护写入，映射私有，映射匿名，映射堆栈，-1，0）=0x7f3e8fa8e000
mprotect（0x7f3e8fa8e000，4096，无保护）=0
克隆（child_stack=0x7f3e9028dfb0，flags=clone_VM | clone_FS | clone_FILES | clone_SIGHAND | clone_THREAD | clone_SYSVSEM | clone| clone|SETTID | clone| child | CLEARTID | PARENT | tidptr
brk（0x55fd6e9cd000）=0x55fd6e9cd000
管道（[3,4]）=0
fcntl（3，F_GETFL）=0（仅限标志）
fcntl（3，F_SETFL，O_RDONLY | O_NONBLOCK）=0
epoll_create（64）=5
epoll_ctl（5，epoll_ctl_ADD，3，{EPOLLIN，{u32=3，u64=3}}）=0
mmap（NULL，8392704，保护读取，保护写入，映射私有，映射匿名，映射堆栈，-1，0）=0x7f3e8f28d000
mprotect（0x7f3e8f28d000，4096，无保护）=0
克隆（子堆栈=0x7f3e8fa8cfb0，标志=clone|VM | clone|FS | clone|u文件| clone|u SIGHAND | clone|SYSVSEM | clone|u setts | clone|父项设置TID | clone|子项CLEARTID |父项tidptr=0x7f3e8fa8d9d0，tls=0x7f3e8fa8d700，子项TId85）=0x7f3e8d309d0
open（“/usr/share/locale/en_US.UTF-8/libdst.cat”，O_RDONLY）=-1 enoint（没有这样的文件或目录）
打开（“/usr/share/locale/en_US.UTF-8/LC_MESSAGES/libdst.cat”，O_RDONLY）=-1 enoint（没有这样的文件或目录）
open（“/usr/share/locale/en/libdst.cat”，ordonly）=-1 enoint（没有这样的文件或目录）
打开（“/usr/share/locale/en/LC_MESSAGES/libdst.cat”，O_RDONLY）=-1 enoint（没有这样的文件或目录）
futex（0x7f3e963f9b20，futex_WAKE_PRIVATE，2147483647）=0
futex（0x7f3e963f9b24，futex_WAKE_PRIVATE，2147483647）=0
brk（0x55fd6e9ee000）=0x55fd6e9ee000
打开（“/usr/lib/ssl/openssl.cnf”，O_RDONLY）=6
fstat（6，{st_mode=S_IFREG | 0644，st_size=10835，…}）=0
阅读（6），#\n#OpenSSL示例配置…，4096）=4096
阅读（6，“网景在BMPStrings上崩溃”或“…，4096）=4096
阅读（6，“这是为了避免解释e”…，4096）=2643
读（6，“，4096）=0
关闭（6）=0
futex（0x7f3e94c480a8，futex_WAKE_PRIVATE，2147483647）=0
打开（“/usr/lib/x86_64-linux-gnu/openssl-1.0.0/engines/libgost.so”，O_RDONLY | O_CLOEXEC）=6
读（6），“\177ELF\2\1\1\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\0\220T\0\0\0\0\0\0”…，832）=832
fstat（6，{st_mode=S_IFREG | 0644，st_size=93280，…}）=0
mmap（NULL，2188320，PROT_READ | PROT_EXEC，MAP_PRIVATE | MAP_DENYWRITE，6,0）=0x7f3e8f076000
mprotect（0x7F3E8F08B0000、2093056、PROT_NONE）=0
mmap（0x7f3e8f28a000，12288，保护读取，保护写入，映射私有，映射固定，映射DENYWRITE，6，0x14000）=0x7f3e8f28a000
关闭（6）=0
M保护（0x7f3e8f28a000，4096，保护读取）=0
打开（“/home/ubuntu user/.digrc”，O_RDONLY）=-1 enoint（没有这样的文件或目录）
打开（“/etc/resolv.conf”，O_RDONLY）=6
fstat（6，{st_mode=S_IFREG | 0644，st_size=208，…}）=0
读取（6，“#Dynamic resolv.conf（5）文件fo”…，4096）=208
读（6，“，4096）=0
关闭（6）=0
getppid（）=3080
rt_sigaction（SIGHUP，{0x7f3e957899e0，~[RTMIN rt_1]，SA_RESTORER，0x7f3e9553f390}，NULL，8）=0
rt_sigsupspend（[]，8）=？ERESTARTNOHAND（如果没有处理程序，则重新启动）
---SIGTERM{si_signo=SIGTERM，si_code=si_TKILL，si_pid=3082，si_uid=1000}---
rt_sigreurn（{mask=[HUP INT TERM]}）=-1 EINTR（中断的系统调用）
futex（0x55fd6df085a0，futex_WAIT_PRIVATE，2，NULL）=0
futex（0x55fd6df085a0，futex_WAKE_PRIVATE，1）=0
futex（0x7f3e90a8f9d0，futex_WAIT，3083，空）=0
写入（4，“\0\0\0\0\377\377\377”，8）=8
epoll_ctl（5，epoll_ctl_DEL，3，0x7fff8ed49d10）=0
关闭（5）=0
关闭（3）=0
关闭（4）=0
futex（0x7f3e965cf07c，futex_WAKE_OP_PRIVATE，1，1，0x7f3e965cf078，{futex_OP_SET，0，futex_OP_CMP_GT，1}）=1
futex（0x7f3e965cf028，futex_WAKE_PRIVATE，1）=1
munmap（0x7f3e8f076000，2188320）=0
munmap（0x7f3e965c8000，266240）=0
写入（1），“\n；DiG 9.10.3-P4-UbuntuDiGstrace-f