SS(8)                                                       SS(8)

     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.

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

          -n, --numeric
               Do not try to resolve service names. Show exact band-
               width 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).

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

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

     Page 1                       Plan 9             (printed 5/23/22)

     SS(8)                                                       SS(8)

               <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)

     Page 2                       Plan 9             (printed 5/23/22)

     SS(8)                                                       SS(8)

               <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 mem-
                    ory.

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

               <ropt_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.

          -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 noti-
                    fication 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

     Page 3                       Plan 9             (printed 5/23/22)

     SS(8)                                                       SS(8)

                    the congestion algorithm name, the default conges-
                    tion 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>

     Page 4                       Plan 9             (printed 5/23/22)

     SS(8)                                                       SS(8)

                    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

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

          -K, --kill
               Attempts to forcibly close sockets. This option dis-
               plays 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

     Page 5                       Plan 9             (printed 5/23/22)

     SS(8)                                                       SS(8)

               is useful when amount of sockets is so huge that pars-
               ing /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 con-
               text.

               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.

     Page 6                       Plan 9             (printed 5/23/22)

     SS(8)                                                       SS(8)

          -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.

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

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

          --inet-sockopt
               Display inet socket options.

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

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

     Page 7                       Plan 9             (printed 5/23/22)

     SS(8)                                                       SS(8)

     STATE-FILTER
          STATE-FILTER allows 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, 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

     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 predi-
          cates, 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 inter-
               face.

          fwmark [=|!=] MASK

     Page 8                       Plan 9             (printed 5/23/22)

     SS(8)                                                       SS(8)

               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 speci-
               fied).

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

               +o = == eq

               +o != ne neq

               +o > gt

               +o < lt

               +o >= ge geq

               +o <= le leq

               +o ! not

               +o | || or

               +o & && 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:

     Page 9                       Plan 9             (printed 5/23/22)

     SS(8)                                                       SS(8)

          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
               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
               List all the tcp sockets in state FIN-WAIT-1 for our

     Page 10                      Plan 9             (printed 5/23/22)

     SS(8)                                                       SS(8)

               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.

     SEE ALSO
          ip(8),
          RFC 793 - https://tools.ietf.org/rfc/rfc793.txt (TCP states)

     AUTHOR
          ss was written by Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>.

          This manual page was written by Michael Prokop
          <mika@grml.org> for the Debian project (but may be used by
          others).

     Page 11                      Plan 9             (printed 5/23/22)