-h

Show summary of options.

-V

Output version information.

-H

Suppress header line.

-n

Do not try to resolve service names.

-r

Try to resolve numeric address/ports.

-a

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

-l

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

-o

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 probetimerkeepalive: tcp keep alive timertimewait: timewait stage timerpersist: zero window probe timerunknown: none of the above timers<expire_time>how long time the timer will expire<retrans>how many times the retran occurs

-e

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

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>)<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. Ifneed memory to send/receive packet, the memory in this cache will be used before allocate addi‐tional 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 receivingpacket, and a new packet is received, it will be put into the sk backlog queue, so it can bereceived by the process immediately

-p

Show process using socket.

-i

Show internal TCP information. Below fields may appear:ts show string "ts" if the timestamp option is setsack show string "sack" if the sack option is setecn show string "ecn" if the explicit congestion notification option is setecnseenshow string "ecnseen" if the saw ecn flag is found in received packetsfastopenshow string "fastopen" if the fastopen option is setcong_algthe 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 factory and receive scale fac‐toryrto:<icsk_rto>tcp re-transmission timeout value, the unit is millisecondbackoff:<icsk_backoff>used for exponential backoff re-transmission, the actual re-transmission timeout value isicsk_rto << icsk_backoffrtt:<rtt>/<rttvar>rtt is the average round trip time, rttvar is the mean deviation of rtt, their units are mil‐lisecondato:<ato>ack timeout, unit is millisecond, used for delay ack modemss:<mss>max segment sizecwnd:<cwnd>congestion window sizepmtu:<pmtu>path MTU valuessthresh:<ssthresh>tcp congestion window slow start thresholdbytes_acked:<bytes_acked>bytes ackedbytes_received:<bytes_received>bytes receivedsegs_out:<segs_out>segments sent outsegs_in:<segs_in>segments receivedsend <send_bps>bpsegress bpslastsnd:<lastsnd>how long time since the last packet sent, the unit is millisecondlastrcv:<lastrcv>how long time since the last packet received, the unit is millisecondlastack:<lastack>how long time since the last ack received, the unit is millisecondpacing_rate <pacing_rate>bps/<max_pacing_rate>bpsthe pacing rate and max pacing ratercv_space:<rcv_space>a helper variable for TCP internal auto tuning socket receive buffer

-K

Attempts to forcibly close sockets. This option displays sockets that are successfully closed andsilently skips sockets that the kernel does not support closing. It supports IPv4 and IPv6 socketsonly.

-s

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

-Z

As the -p option but also shows process 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 socketactive.

-z

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

-N

Switch to the specified network namespace name.

-b

Show socket BPF filters (only administrators are allowed to get these information).

-4

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

-6

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

-0

Display PACKET sockets (alias for -f link).

-t

Display TCP sockets.

-u

Display UDP sockets.

-d

Display DCCP sockets.

-w

Display RAW sockets.

-x

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

-S

Display SCTP sockets.

--vsock

Display vsock sockets (alias for -f vsock).

-f

Display sockets of type FAMILY. Currently the following families are supported: unix, inet, inet6,link, netlink, vsock.

-A

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.

-D

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

-F

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-FILTERSTATE-FILTER allows to construct arbitrary set of states to match. Its syntax is sequence of keywords stateand 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 statesconnected - all the states except for listening and closedsynchronized - all the connected states except for syn-sentbucket - states, which are maintained as minisockets, i.e. time-wait and syn-recvbig - opposite to bucketUSAGE EXAMPLESss -t -aDisplay all TCP sockets.ss -t -a -ZDisplay all TCP sockets with process SELinux security contexts.ss -u -aDisplay 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 193.233.7/24List all the tcp sockets in state FIN-WAIT-1 for our apache to network 193.233.7/24 and look at theirtimers.