ss命令

发表于2020-02-18|更新于2025-03-24|科技·TechLinux工具箱·Linux Toolbox

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命令用途

ss 命令主要用于显示套接字信息，可以用来查看系统当前活动的网络连接和其状态。它能提供关于 TCP、UDP、Unix 域套接字等多种协议的详细数据。

常用用法示例

查看所有 TCP 套接字

ss -t -a
State      Recv-Q    Send-Q        Local Address:Port        Peer Address:Port
ESTAB      0         0             192.168.1.10:ssh         192.168.1.2:22
LISTEN     0         128           0.0.0.0:http              0.0.0.0:*

State 表示套接字的当前状态（如 ESTAB 表示已建立连接，LISTEN 表示正在监听）。
Recv-Q 和 Send-Q 表示接收和发送队列的大小。
Local Address:Port 和 Peer Address:Port 分别表示本地和远程的地址与端口。

查看所有 UDP 套接字

ss -u -a
State      Recv-Q    Send-Q        Local Address:Port        Peer Address:Port
UNCONN     0         0             0.0.0.0:123               0.0.0.0:*
UNCONN     0         0             0.0.0.0:53                0.0.0.0:*

这种输出展示了所有未连接的 UDP 套接字。

查看 SSH 连接

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ss -o state established '( dport = :ssh or sport = :ssh )'
State      Recv-Q    Send-Q        Local Address:Port        Peer Address:Port
ESTAB      0         0             192.168.1.10:ssh         192.168.1.2:22

该命令列出了所有已建立的 SSH 连接。

常用参数选项

-h, –help：显示命令的帮助信息。
-V, –version：输出 ss 命令的版本信息。
-n, –numeric：不解析服务名称，显示精确的端口号。
-a, –all：显示所有套接字，包括监听和非监听状态的套接字。
-l, –listening：仅显示监听状态的套接字。
-o, –options：显示定时器信息（如 TCP 重传定时器、连接保持活跃定时器等）。
-p, –processes：显示使用套接字的进程信息。
-T, –threads：显示使用套接字的线程信息，默认与 -p 选项一起使用。
-e, –extended：显示详细的套接字信息，如 UID、inode 等。
-s, –summary：打印套接字的统计信息，适用于大量套接字的情况。
-4, –ipv4：仅显示 IPv4 套接字。
-6, –ipv6：仅显示 IPv6 套接字。
-t, –tcp：仅显示 TCP 套接字。
-u, –udp：仅显示 UDP 套接字。

原厂文档

NAME

   ss - another utility to investigate sockets

SYNOPSIS

   ss [options] [ FILTER ]

DESCRIPTION

   ss is used to dump socket statistics. It allows showing
   information similar to netstat.  It can display more TCP and state
   information than other tools.

OPTIONS

   When no option is used ss displays a list of open non-listening
   sockets (e.g. TCP/UNIX/UDP) that have established connection.

   -h, --help
          Show summary of options.

   -V, --version
          Output version information.

   -H, --no-header
          Suppress header line.

   -Q, --no-queues
          Suppress sending and receiving queue columns.

   -O, --oneline
          Print each socket's data on a single line.

   -n, --numeric
          Do not try to resolve service names. Show exact bandwidth
          values, instead of human-readable.

   -r, --resolve
          Try to resolve numeric address/ports.

   -a, --all
          Display both listening and non-listening (for TCP this
          means established connections) sockets.

   -l, --listening
          Display only listening sockets (these are omitted by
          default).

   -B, --bound-inactive
          Display only TCP bound but inactive (not listening,
          connecting, etc.) sockets (these are omitted by default).

   -o, --options
          Show timer information. For TCP protocol, the output format
          is:

          timer:(<timer_name>,<expire_time>,<retrans>)

          <timer_name>
                 the name of the timer, there are five kind of timer
                 names:

                 on : means one of these timers: TCP retrans timer,
                 TCP early retrans timer and tail loss probe timer

                 keepalive: tcp keep alive timer

                 timewait: timewait stage timer

                 persist: zero window probe timer

                 unknown: none of the above timers

          <expire_time>
                 how long time the timer will expire

          <retrans>
                 how many times the retransmission occurred

   -e, --extended
          Show detailed socket information. The output format is:

          uid:<uid_number> ino:<inode_number> sk:<cookie>

          <uid_number>
                 the user id the socket belongs to

          <inode_number>
                 the socket's inode number in VFS

          <cookie>
                 an uuid of the socket

   -m, --memory
          Show socket memory usage. The output format is:

          skmem:(r<rmem_alloc>,rb<rcv_buf>,t<wmem_alloc>,tb<snd_buf>,
                        f<fwd_alloc>,w<wmem_queued>,o<opt_mem>,
                        bl<back_log>,d<sock_drop>)

          <rmem_alloc>
                 the memory allocated for receiving packet

          <rcv_buf>
                 the total memory can be allocated for receiving
                 packet

          <wmem_alloc>
                 the memory used for sending packet (which has been
                 sent to layer 3)

          <snd_buf>
                 the total memory can be allocated for sending packet

          <fwd_alloc>
                 the memory allocated by the socket as cache, but not
                 used for receiving/sending packet yet. If need
                 memory to send/receive packet, the memory in this
                 cache will be used before allocate additional
                 memory.

          <wmem_queued>
                 The memory allocated for sending packet (which has
                 not been sent to layer 3)

          <opt_mem>
                 The memory used for storing socket option, e.g., the
                 key for TCP MD5 signature

          <back_log>
                 The memory used for the sk backlog queue. On a
                 process context, if the process is receiving packet,
                 and a new packet is received, it will be put into
                 the sk backlog queue, so it can be received by the
                 process immediately

          <sock_drop>
                 the number of packets dropped before they are de-
                 multiplexed into the socket

   -p, --processes
          Show process using socket.

   -T, --threads
          Show thread using socket. Implies -p.

   -i, --info
          Show internal TCP information. Below fields may appear:

          ts     show string "ts" if the timestamp option is set

          sack   show string "sack" if the sack option is set

          ecn    show string "ecn" if the explicit congestion
                 notification option is set

          ecnseen
                 show string "ecnseen" if the saw ecn flag is found
                 in received packets

          fastopen
                 show string "fastopen" if the fastopen option is set

          cong_alg
                 the congestion algorithm name, the default
                 congestion algorithm is "cubic"

          wscale:<snd_wscale>:<rcv_wscale>
                 if window scale option is used, this field shows the
                 send scale factor and receive scale factor

          rto:<icsk_rto>
                 tcp re-transmission timeout value, the unit is
                 millisecond

          backoff:<icsk_backoff>
                 used for exponential backoff re-transmission, the
                 actual re-transmission timeout value is icsk_rto <<
                 icsk_backoff

          rtt:<rtt>/<rttvar>
                 rtt is the average round trip time, rttvar is the
                 mean deviation of rtt, their units are millisecond

          ato:<ato>
                 ack timeout, unit is millisecond, used for delay ack
                 mode

          mss:<mss>
                 max segment size

          cwnd:<cwnd>
                 congestion window size

          pmtu:<pmtu>
                 path MTU value

          ssthresh:<ssthresh>
                 tcp congestion window slow start threshold

          bytes_acked:<bytes_acked>
                 bytes acked

          bytes_received:<bytes_received>
                 bytes received

          segs_out:<segs_out>
                 segments sent out

          segs_in:<segs_in>
                 segments received

          send <send_bps>bps
                 egress bps

          lastsnd:<lastsnd>
                 how long time since the last packet sent, the unit
                 is millisecond

          lastrcv:<lastrcv>
                 how long time since the last packet received, the
                 unit is millisecond

          lastack:<lastack>
                 how long time since the last ack received, the unit
                 is millisecond

          pacing_rate <pacing_rate>bps/<max_pacing_rate>bps
                 the pacing rate and max pacing rate

          rcv_space:<rcv_space>
                 a helper variable for TCP internal auto tuning
                 socket receive buffer

          tcp-ulp-mptcp flags:[MmBbJjecv]
          token:<rem_token(rem_id)/loc_token(loc_id)> seq:<sn>
          sfseq:<ssn> ssnoff:<off> maplen:<maplen>
                 MPTCP subflow information

   --tos  Show ToS and priority information. Below fields may appear:

          tos    IPv4 Type-of-Service byte

          tclass IPv6 Traffic Class byte

          class_id
                 Class id set by net_cls cgroup. If class is zero
                 this shows priority set by SO_PRIORITY.

   --cgroup
          Show cgroup information. Below fields may appear:

          cgroup Cgroup v2 pathname. This pathname is relative to the
                 mount point of the hierarchy.

   --tipcinfo
          Show internal tipc socket information.

   -K, --kill
          Attempts to forcibly close sockets. This option displays
          sockets that are successfully closed and silently skips
          sockets that the kernel does not support closing. It
          supports IPv4 and IPv6 sockets only.

   -s, --summary
          Print summary statistics. This option does not parse socket
          lists obtaining summary from various sources. It is useful
          when amount of sockets is so huge that parsing
          /proc/net/tcp is painful.

   -E, --events
          Continually display sockets as they are destroyed

   -Z, --context
          As the -p option but also shows process security context.
          If the -T option is used, also shows thread security
          context.

          For netlink(7) sockets the initiating process context is
          displayed as follows:

                 1.  If valid pid show the process context.

                 2.  If destination is kernel (pid = 0) show kernel
                     initial context.

                 3.  If a unique identifier has been allocated by the
                     kernel or netlink user, show context as
                     "unavailable". This will generally indicate that
                     a process has more than one netlink socket
                     active.

   -z, --contexts
          As the -Z option but also shows the socket context. The
          socket context is taken from the associated inode and is
          not the actual socket context held by the kernel. Sockets
          are typically labeled with the context of the creating
          process, however the context shown will reflect any policy
          role, type and/or range transition rules applied, and is
          therefore a useful reference.

   -N NSNAME, --net=NSNAME
          Switch to the specified network namespace name.

   -b, --bpf
          Show socket classic BPF filters (only administrators are
          allowed to get these information).

   -4, --ipv4
          Display only IP version 4 sockets (alias for -f inet).

   -6, --ipv6
          Display only IP version 6 sockets (alias for -f inet6).

   -0, --packet
          Display PACKET sockets (alias for -f link).

   -t, --tcp
          Display TCP sockets.

   -u, --udp
          Display UDP sockets.

   -d, --dccp
          Display DCCP sockets.

   -w, --raw
          Display RAW sockets.

   -x, --unix
          Display Unix domain sockets (alias for -f unix).

   -S, --sctp
          Display SCTP sockets.

   --tipc Display tipc sockets (alias for -f tipc).

   --vsock
          Display vsock sockets (alias for -f vsock).

   --xdp  Display XDP sockets (alias for -f xdp).

   -M, --mptcp
          Display MPTCP sockets.

   --inet-sockopt
          Display inet socket options.

   -f FAMILY, --family=FAMILY
          Display sockets of type FAMILY.  Currently the following
          families are supported: unix, inet, inet6, link, netlink,
          vsock, tipc, xdp.

   -A QUERY, --query=QUERY, --socket=QUERY
          List of socket tables to dump, separated by commas. The
          following identifiers are understood: all, inet, tcp, udp,
          raw, unix, packet, netlink, unix_dgram, unix_stream,
          unix_seqpacket, packet_raw, packet_dgram, dccp, sctp, tipc,
          vsock_stream, vsock_dgram, xdp, mptcp. Any item in the list
          may optionally be prefixed by an exclamation mark (!)  to
          exclude that socket table from being dumped.

   -D FILE, --diag=FILE
          Do not display anything, just dump raw information about
          TCP sockets to FILE after applying filters. If FILE is -
          stdout is used.

   -F FILE, --filter=FILE
          Read filter information from FILE.  Each line of FILE is
          interpreted like single command line option. If FILE is -
          stdin is used.

   --bpf-maps
          Pretty-print all the BPF socket-local data entries for each
          socket.

   --bpf-map-id=MAP_ID
          Pretty-print the BPF socket-local data entries for the
          requested map ID. Can be used more than once.

   FILTER := [ state STATE-FILTER ] [ EXPRESSION ]
          Please take a look at the official documentation for
          details regarding filters.

STATE-FILTER

   STATE-FILTER allows one to construct arbitrary set of states to
   match. Its syntax is sequence of keywords state and exclude
   followed by identifier of state.

   Available identifiers are:

          All standard TCP states: established, syn-sent, syn-recv,
          fin-wait-1, fin-wait-2, time-wait, closed, close-wait,
          last-ack, listening and closing.

          all - for all the states

          connected - all the states except for listening and closed

          synchronized - all the connected states except for syn-sent

          bucket - states, which are maintained as minisockets, i.e.
          time-wait and syn-recv

          big - opposite to bucket

          bound-inactive - bound but otherwise inactive sockets (not
          listening, connecting, etc.)

EXPRESSION

   EXPRESSION allows filtering based on specific criteria.
   EXPRESSION consists of a series of predicates combined by boolean
   operators. The possible operators in increasing order of
   precedence are or (or | or ||), and (or & or &&), and not (or !).
   If no operator is between consecutive predicates, an implicit and
   operator is assumed. Subexpressions can be grouped with "(" and
   ")".

   The following predicates are supported:

   {dst|src} [=] HOST
          Test if the destination or source matches HOST. See HOST
          SYNTAX for details.

   {dport|sport} [OP] [FAMILY:]:PORT
          Compare the destination or source port to PORT. OP can be
          any of "<", "<=", "=", "!=", ">=" and ">". Following normal
          arithmetic rules. FAMILY and PORT are as described in HOST
          SYNTAX below.

   dev [=|!=] DEVICE
          Match based on the device the connection uses. DEVICE can
          either be a device name or the index of the interface.

   fwmark [=|!=] MASK
          Matches based on the fwmark value for the connection. This
          can either be a specific mark value or a mark value
          followed by a "/" and a bitmask of which bits to use in the
          comparison. For example "fwmark = 0x01/0x03" would match if
          the two least significant bits of the fwmark were 0x01.

   cgroup [=|!=] PATH
          Match if the connection is part of a cgroup at the given
          path.

   autobound
          Match if the port or path of the source address was
          automatically allocated (rather than explicitly specified).

   Most operators have aliases. If no operator is supplied "=" is
   assumed.  Each of the following groups of operators are all
   equivalent:

          • = == eq

          • != ne neq

          • > gt

          • < lt

          • >= ge geq

          • <= le leq

          • ! not

          • | || or

          • & && and

HOST SYNTAX

   The general host syntax is [FAMILY:]ADDRESS[:PORT].

   FAMILY must be one of the families supported by the -f option. If
   not given it defaults to the family given with the -f option, and
   if that is also missing, will assume either inet or inet6. Note
   that all host conditions in the expression should either all be
   the same family or be only inet and inet6. If there is some other
   mixture of families, the results will probably be unexpected.

   The form of ADDRESS and PORT depends on the family used. "*" can
   be used as a wildcard for either the address or port. The details
   for each family are as follows:

   unix   ADDRESS is a glob pattern (see fnmatch(3)) that will be
          matched case-insensitively against the unix socket's
          address. Both path and abstract names are supported. Unix
          addresses do not support a port, and "*" cannot be used as
          a wildcard.

   link   ADDRESS is the case-insensitive name of an Ethernet
          protocol to match. PORT is either a device name or a device
          index for the desired link device, as seen in the output of
          ip link.

   netlink
          ADDRESS is a descriptor of the netlink family. Possible
          values come from /etc/iproute2/nl_protos. PORT is the port
          id of the socket, which is usually the same as the owning
          process id. The value "kernel" can be used to represent the
          kernel (port id of 0).

   vsock  ADDRESS is an integer representing the CID address, and
          PORT is the port.

   inet and inet6
          ADDRESS is an ip address (either v4 or v6 depending on the
          family) or a DNS hostname that resolves to an ip address of
          the required version. An ipv6 address must be enclosed in
          "[" and "]" to disambiguate the port separator. The address
          may additionally have a prefix length given in CIDR
          notation (a slash followed by the prefix length in bits).
          PORT is either the numerical socket port, or the service
          name for the port to match.

USAGE EXAMPLES

   ss -t -a
          Display all TCP sockets.

   ss -t -a -Z
          Display all TCP sockets with process SELinux security
          contexts.

   ss -u -a
          Display all UDP sockets.

   ss -o state established '( dport = :ssh or sport = :ssh )'
          Display all established ssh connections.

   ss -x src /tmp/.X11-unix/*
          Find all local processes connected to X server.

   ss -o state fin-wait-1 '( sport = :http or sport = :https )' dst
   193.233.7/24
          List all the tcp sockets in state FIN-WAIT-1 for our apache
          to network 193.233.7/24 and look at their timers.

   ss -a -A 'all,!tcp'
          List sockets in all states from all socket tables but TCP.