noble (8) ss.8.gz

Provided by: iproute2_6.1.0-1ubuntu6_amd64 bug

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 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).

       -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.  -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.

              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

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.

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).

                                                                                                           SS(8)