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NAME | SYNOPSIS | DESCRIPTION | OPTIONS | STATE-FILTER | USAGE EXAMPLES | SEE ALSO | AUTHOR | COLOPHON |
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SS(8) System Manager's Manual SS(8)
ss - another utility to investigate sockets
ss [options] [ FILTER ]
ss is used to dump socket statistics. It allows showing information
similar to netstat. It can display more TCP and state informations
than other tools.
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.
-n, --numeric
Do not try to resolve service names.
-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 retran occurs
-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>)
<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
-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 factory and receive scale factory
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
-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.
-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 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).
-f FAMILY, --family=FAMILY
Display sockets of type FAMILY. Currently the following
families are supported: unix, inet, inet6, link, netlink,
vsock.
-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.
-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 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, 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
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.
ip(8),
RFC 793 - https://tools.ietf.org/rfc/rfc793.txt (TCP states)
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).
This page is part of the iproute2 (utilities for controlling TCP/IP
networking and traffic) project. Information about the project can
be found at
⟨http://www.linuxfoundation.org/collaborate/workgroups/networking/iproute2⟩.
If you have a bug report for this manual page, send it to
netdev@vger.kernel.org, shemminger@osdl.org. This page was obtained
from the project's upstream Git repository
⟨git://git.kernel.org/pub/scm/linux/kernel/git/shemminger/iproute2.git⟩
on 2018-02-02. (At that time, the date of the most recent commit
that was found in the repository was 2018-01-29.) If you discover
any rendering problems in this HTML version of the page, or you
believe there is a better or more up-to-date source for the page, or
you have corrections or improvements to the information in this
COLOPHON (which is not part of the original manual page), send a mail
to man-pages@man7.org
SS(8)
Pages that refer to this page: netstat(8), ping(8)
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