# ss

## 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.
    


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