man/man8/ss.8

   1 .TH SS 8
   2 .SH NAME
   3 ss \- another utility to investigate sockets
   4 .SH SYNOPSIS
   5 .B ss
   6 .RI [ options ] " [ FILTER ]"
   7 .SH DESCRIPTION
   8 .B ss
   9 is used to dump socket statistics. It allows showing information similar
  10 to
  11 .IR netstat .
  12 It can display more TCP and state information than other tools.
  13
  14 .SH OPTIONS
  15 When no option is used ss displays a list of open non-listening
  16 sockets (e.g. TCP/UNIX/UDP) that have established connection.
  17 .TP
  18 .B \-h, \-\-help
  19 Show summary of options.
  20 .TP
  21 .B \-V, \-\-version
  22 Output version information.
  23 .TP
  24 .B \-H, \-\-no-header
  25 Suppress header line.
  26 .TP
  27 .B \-O, \-\-oneline
  28 Print each socket's data on a single line.
  29 .TP
  30 .B \-n, \-\-numeric
  31 Do not try to resolve service names. Show exact bandwidth values, instead of human-readable.
  32 .TP
  33 .B \-r, \-\-resolve
  34 Try to resolve numeric address/ports.
  35 .TP
  36 .B \-a, \-\-all
  37 Display both listening and non-listening (for TCP this means
  38 established connections) sockets.
  39 .TP
  40 .B \-l, \-\-listening
  41 Display only listening sockets (these are omitted by default).
  42 .TP
  43 .B \-o, \-\-options
  44 Show timer information. For TCP protocol, the output format is:
  45 .RS
  46 .P
  47 timer:(<timer_name>,<expire_time>,<retrans>)
  48 .P
  49 .TP
  50 .B <timer_name>
  51 the name of the timer, there are five kind of timer names:
  52 .RS
  53 .P
  54 .B on
  55 : means one of these timers: TCP retrans timer, TCP early retrans
  56 timer and tail loss probe timer
  57 .P
  58 .BR keepalive ": tcp keep alive timer"
  59 .P
  60 .BR timewait ": timewait stage timer"
  61 .P
  62 .BR persist ": zero window probe timer"
  63 .P
  64 .BR unknown ": none of the above timers"
  65 .RE
  66 .TP
  67 .B <expire_time>
  68 how long time the timer will expire
  69 .P
  70 .TP
  71 .B <retrans>
  72 how many times the retransmission occured
  73 .RE
  74 .TP
  75 .B \-e, \-\-extended
  76 Show detailed socket information. The output format is:
  77 .RS
  78 .P
  79 uid:<uid_number> ino:<inode_number> sk:<cookie>
  80 .P
  81 .TP
  82 .B <uid_number>
  83 the user id the socket belongs to
  84 .P
  85 .TP
  86 .B <inode_number>
  87 the socket's inode number in VFS
  88 .P
  89 .TP
  90 .B <cookie>
  91 an uuid of the socket
  92 .RE
  93 .TP
  94 .B \-m, \-\-memory
  95 Show socket memory usage. The output format is:
  96 .RS
  97 .P
  98 skmem:(r<rmem_alloc>,rb<rcv_buf>,t<wmem_alloc>,tb<snd_buf>,
  99 .br
 100 .RS
 101 .RS
 102 f<fwd_alloc>,w<wmem_queued>,o<opt_mem>,
 103 .RE
 104 .RE
 105 .br
 106 .RS
 107 .RS
 108 bl<back_log>,d<sock_drop>)
 109 .RE
 110 .RE
 111 .P
 112 .TP
 113 .B <rmem_alloc>
 114 the memory allocated for receiving packet
 115 .P
 116 .TP
 117 .B <rcv_buf>
 118 the total memory can be allocated for receiving packet
 119 .P
 120 .TP
 121 .B <wmem_alloc>
 122 the memory used for sending packet (which has been sent to layer 3)
 123 .P
 124 .TP
 125 .B <snd_buf>
 126 the total memory can be allocated for sending packet
 127 .P
 128 .TP
 129 .B <fwd_alloc>
 130 the memory allocated by the socket as cache, but not used for
 131 receiving/sending packet yet. If need memory to send/receive packet,
 132 the memory in this cache will be used before allocate additional
 133 memory.
 134 .P
 135 .TP
 136 .B <wmem_queued>
 137 The memory allocated for sending packet (which has not been sent to layer 3)
 138 .P
 139 .TP
 140 .B <ropt_mem>
 141 The memory used for storing socket option, e.g., the key for TCP MD5 signature
 142 .P
 143 .TP
 144 .B <back_log>
 145 The memory used for the sk backlog queue. On a process context, if the
 146 process is receiving packet, and a new packet is received, it will be
 147 put into the sk backlog queue, so it can be received by the process
 148 immediately
 149 .P
 150 .TP
 151 .B <sock_drop>
 152 the number of packets dropped before they are de-multiplexed into the socket
 153 .RE
 154 .TP
 155 .B \-p, \-\-processes
 156 Show process using socket.
 157 .TP
 158 .B \-i, \-\-info
 159 Show internal TCP information. Below fields may appear:
 160 .RS
 161 .P
 162 .TP
 163 .B ts
 164 show string "ts" if the timestamp option is set
 165 .P
 166 .TP
 167 .B sack
 168 show string "sack" if the sack option is set
 169 .P
 170 .TP
 171 .B ecn
 172 show string "ecn" if the explicit congestion notification option is set
 173 .P
 174 .TP
 175 .B ecnseen
 176 show string "ecnseen" if the saw ecn flag is found in received packets
 177 .P
 178 .TP
 179 .B fastopen
 180 show string "fastopen" if the fastopen option is set
 181 .P
 182 .TP
 183 .B cong_alg
 184 the congestion algorithm name, the default congestion algorithm is "cubic"
 185 .P
 186 .TP
 187 .B wscale:<snd_wscale>:<rcv_wscale>
 188 if window scale option is used, this field shows the send scale factor
 189 and receive scale factor
 190 .P
 191 .TP
 192 .B rto:<icsk_rto>
 193 tcp re-transmission timeout value, the unit is millisecond
 194 .P
 195 .TP
 196 .B backoff:<icsk_backoff>
 197 used for exponential backoff re-transmission, the actual
 198 re-transmission timeout value is icsk_rto << icsk_backoff
 199 .P
 200 .TP
 201 .B rtt:<rtt>/<rttvar>
 202 rtt is the average round trip time, rttvar is the mean deviation of
 203 rtt, their units are millisecond
 204 .P
 205 .TP
 206 .B ato:<ato>
 207 ack timeout, unit is millisecond, used for delay ack mode
 208 .P
 209 .TP
 210 .B mss:<mss>
 211 max segment size
 212 .P
 213 .TP
 214 .B cwnd:<cwnd>
 215 congestion window size
 216 .P
 217 .TP
 218 .B pmtu:<pmtu>
 219 path MTU value
 220 .P
 221 .TP
 222 .B ssthresh:<ssthresh>
 223 tcp congestion window slow start threshold
 224 .P
 225 .TP
 226 .B bytes_acked:<bytes_acked>
 227 bytes acked
 228 .P
 229 .TP
 230 .B bytes_received:<bytes_received>
 231 bytes received
 232 .P
 233 .TP
 234 .B segs_out:<segs_out>
 235 segments sent out
 236 .P
 237 .TP
 238 .B segs_in:<segs_in>
 239 segments received
 240 .P
 241 .TP
 242 .B send <send_bps>bps
 243 egress bps
 244 .P
 245 .TP
 246 .B lastsnd:<lastsnd>
 247 how long time since the last packet sent, the unit is millisecond
 248 .P
 249 .TP
 250 .B lastrcv:<lastrcv>
 251 how long time since the last packet received, the unit is millisecond
 252 .P
 253 .TP
 254 .B lastack:<lastack>
 255 how long time since the last ack received, the unit is millisecond
 256 .P
 257 .TP
 258 .B pacing_rate <pacing_rate>bps/<max_pacing_rate>bps
 259 the pacing rate and max pacing rate
 260 .P
 261 .TP
 262 .B rcv_space:<rcv_space>
 263 a helper variable for TCP internal auto tuning socket receive buffer
 264 .P
 265 .TP
 266 .B tcp-ulp-mptcp flags:[MmBbJjecv] token:<rem_token(rem_id)/loc_token(loc_id)> seq:<sn> sfseq:<ssn> ssnoff:<off> maplen:<maplen>
 267 MPTCP subflow information
 268 .P
 269 .RE
 270 .TP
 271 .B \-\-tos
 272 Show ToS and priority information. Below fields may appear:
 273 .RS
 274 .P
 275 .TP
 276 .B tos
 277 IPv4 Type-of-Service byte
 278 .P
 279 .TP
 280 .B tclass
 281 IPv6 Traffic Class byte
 282 .P
 283 .TP
 284 .B class_id
 285 Class id set by net_cls cgroup. If class is zero this shows priority
 286 set by SO_PRIORITY.
 287 .RE
 288 .TP
 289 .B \-\-cgroup
 290 Show cgroup information. Below fields may appear:
 291 .RS
 292 .P
 293 .TP
 294 .B cgroup
 295 Cgroup v2 pathname. This pathname is relative to the mount point of the hierarchy.
 296 .RE
 297 .TP
 298 .B \-K, \-\-kill
 299 Attempts to forcibly close sockets. This option displays sockets that are
 300 successfully closed and silently skips sockets that the kernel does not support
 301 closing. It supports IPv4 and IPv6 sockets only.
 302 .TP
 303 .B \-s, \-\-summary
 304 Print summary statistics. This option does not parse socket lists obtaining
 305 summary from various sources. It is useful when amount of sockets is so huge
 306 that parsing /proc/net/tcp is painful.
 307 .TP
 308 .B \-E, \-\-events
 309 Continually display sockets as they are destroyed
 310 .TP
 311 .B \-Z, \-\-context
 312 As the
 313 .B \-p
 314 option but also shows process security context.
 315 .sp
 316 For
 317 .BR netlink (7)
 318 sockets the initiating process context is displayed as follows:
 319 .RS
 320 .RS
 321 .IP "1." 4
 322 If valid pid show the process context.
 323 .IP "2." 4
 324 If destination is kernel (pid = 0) show kernel initial context.
 325 .IP "3." 4
 326 If a unique identifier has been allocated by the kernel or netlink user,
 327 show context as "unavailable". This will generally indicate that a
 328 process has more than one netlink socket active.
 329 .RE
 330 .RE
 331 .TP
 332 .B \-z, \-\-contexts
 333 As the
 334 .B \-Z
 335 option but also shows the socket context. The socket context is
 336 taken from the associated inode and is not the actual socket
 337 context held by the kernel. Sockets are typically labeled with the
 338 context of the creating process, however the context shown will reflect
 339 any policy role, type and/or range transition rules applied,
 340 and is therefore a useful reference.
 341 .TP
 342 .B \-N NSNAME, \-\-net=NSNAME
 343 Switch to the specified network namespace name.
 344 .TP
 345 .B \-b, \-\-bpf
 346 Show socket BPF filters (only administrators are allowed to get these
 347 information).
 348 .TP
 349 .B \-4, \-\-ipv4
 350 Display only IP version 4 sockets (alias for -f inet).
 351 .TP
 352 .B \-6, \-\-ipv6
 353 Display only IP version 6 sockets (alias for -f inet6).
 354 .TP
 355 .B \-0, \-\-packet
 356 Display PACKET sockets (alias for -f link).
 357 .TP
 358 .B \-t, \-\-tcp
 359 Display TCP sockets.
 360 .TP
 361 .B \-u, \-\-udp
 362 Display UDP sockets.
 363 .TP
 364 .B \-d, \-\-dccp
 365 Display DCCP sockets.
 366 .TP
 367 .B \-w, \-\-raw
 368 Display RAW sockets.
 369 .TP
 370 .B \-x, \-\-unix
 371 Display Unix domain sockets (alias for -f unix).
 372 .TP
 373 .B \-S, \-\-sctp
 374 Display SCTP sockets.
 375 .TP
 376 .B \-\-vsock
 377 Display vsock sockets (alias for -f vsock).
 378 .TP
 379 .B \-\-xdp
 380 Display XDP sockets (alias for -f xdp).
 381 .TP
 382 .B \-\-inet-sockopt
 383 Display inet socket options.
 384 .TP
 385 .B \-f FAMILY, \-\-family=FAMILY
 386 Display sockets of type FAMILY.  Currently the following families are
 387 supported: unix, inet, inet6, link, netlink, vsock, xdp.
 388 .TP
 389 .B \-A QUERY, \-\-query=QUERY, \-\-socket=QUERY
 390 List of socket tables to dump, separated by commas. The following identifiers
 391 are understood: all, inet, tcp, udp, raw, unix, packet, netlink, unix_dgram,
 392 unix_stream, unix_seqpacket, packet_raw, packet_dgram, dccp, sctp,
 393 vsock_stream, vsock_dgram, xdp Any item in the list may optionally be
 394 prefixed by an exclamation mark
 395 .RB ( ! )
 396 to exclude that socket table from being dumped.
 397 .TP
 398 .B \-D FILE, \-\-diag=FILE
 399 Do not display anything, just dump raw information about TCP sockets
 400 to FILE after applying filters. If FILE is - stdout is used.
 401 .TP
 402 .B \-F FILE, \-\-filter=FILE
 403 Read filter information from FILE.  Each line of FILE is interpreted
 404 like single command line option. If FILE is - stdin is used.
 405 .TP
 406 .B FILTER := [ state STATE-FILTER ] [ EXPRESSION ]
 407 Please take a look at the official documentation for details regarding filters.
 408
 409 .SH STATE-FILTER
 410
 411 .B STATE-FILTER
 412 allows to construct arbitrary set of states to match. Its syntax is
 413 sequence of keywords state and exclude followed by identifier of
 414 state.
 415 .TP
 416 Available identifiers are:
 417
 418 All standard TCP states:
 419 .BR established ", " syn-sent ", " syn-recv ", " fin-wait-1 ", " fin-wait-2 ", " time-wait ", " closed ", " close-wait ", " last-ack ", "
 420 .BR  listening " and " closing.
 421
 422 .B all
 423 - for all the states
 424
 425 .B connected
 426 - all the states except for
 427 .BR listening " and " closed
 428
 429 .B synchronized
 430 - all the
 431 .B connected
 432 states except for
 433 .B syn-sent
 434
 435 .B bucket
 436 - states, which are maintained as minisockets, i.e.
 437 .BR time-wait " and " syn-recv
 438
 439 .B big
 440 - opposite to
 441 .B bucket
 442
 443 .SH USAGE EXAMPLES
 444 .TP
 445 .B ss -t -a
 446 Display all TCP sockets.
 447 .TP
 448 .B ss -t -a -Z
 449 Display all TCP sockets with process SELinux security contexts.
 450 .TP
 451 .B ss -u -a
 452 Display all UDP sockets.
 453 .TP
 454 .B ss -o state established '( dport = :ssh or sport = :ssh )'
 455 Display all established ssh connections.
 456 .TP
 457 .B ss -x src /tmp/.X11-unix/*
 458 Find all local processes connected to X server.
 459 .TP
 460 .B ss -o state fin-wait-1 '( sport = :http or sport = :https )' dst 193.233.7/24
 461 List all the tcp sockets in state FIN-WAIT-1 for our apache to network
 462 193.233.7/24 and look at their timers.
 463 .TP
 464 .B ss -a -A 'all,!tcp'
 465 List sockets in all states from all socket tables but TCP.
 466 .SH SEE ALSO
 467 .BR ip (8),
 468 .br
 469 .BR RFC " 793 "
 470 - https://tools.ietf.org/rfc/rfc793.txt (TCP states)
 471
 472 .SH AUTHOR
 473 .I ss
 474 was written by Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>.
 475 .PP
 476 This manual page was written by Michael Prokop <mika@grml.org>
 477 for the Debian project (but may be used by others).