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)
<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
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.
-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.
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.
--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 following
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 ] [ EXPRESSION ]
Please take a look at the official documentation for
details regarding filters.
