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 .RE
 265 .TP
 266 .B \-\-tos
 267 Show ToS and priority information. Below fields may appear:
 268 .RS
 269 .P
 270 .TP
 271 .B tos
 272 IPv4 Type-of-Service byte
 273 .P
 274 .TP
 275 .B tclass
 276 IPv6 Traffic Class byte
 277 .P
 278 .TP
 279 .B class_id
 280 Class id set by net_cls cgroup. If class is zero this shows priority
 281 set by SO_PRIORITY.
 282 .RE
 283 .TP
 284 .B \-K, \-\-kill
 285 Attempts to forcibly close sockets. This option displays sockets that are
 286 successfully closed and silently skips sockets that the kernel does not support
 287 closing. It supports IPv4 and IPv6 sockets only.
 288 .TP
 289 .B \-s, \-\-summary
 290 Print summary statistics. This option does not parse socket lists obtaining
 291 summary from various sources. It is useful when amount of sockets is so huge
 292 that parsing /proc/net/tcp is painful.
 293 .TP
 294 .B \-E, \-\-events
 295 Continually display sockets as they are destroyed
 296 .TP
 297 .B \-Z, \-\-context
 298 As the
 299 .B \-p
 300 option but also shows process security context.
 301 .sp
 302 For
 303 .BR netlink (7)
 304 sockets the initiating process context is displayed as follows:
 305 .RS
 306 .RS
 307 .IP "1." 4
 308 If valid pid show the process context.
 309 .IP "2." 4
 310 If destination is kernel (pid = 0) show kernel initial context.
 311 .IP "3." 4
 312 If a unique identifier has been allocated by the kernel or netlink user,
 313 show context as "unavailable". This will generally indicate that a
 314 process has more than one netlink socket active.
 315 .RE
 316 .RE
 317 .TP
 318 .B \-z, \-\-contexts
 319 As the
 320 .B \-Z
 321 option but also shows the socket context. The socket context is
 322 taken from the associated inode and is not the actual socket
 323 context held by the kernel. Sockets are typically labeled with the
 324 context of the creating process, however the context shown will reflect
 325 any policy role, type and/or range transition rules applied,
 326 and is therefore a useful reference.
 327 .TP
 328 .B \-N NSNAME, \-\-net=NSNAME
 329 Switch to the specified network namespace name.
 330 .TP
 331 .B \-b, \-\-bpf
 332 Show socket BPF filters (only administrators are allowed to get these
 333 information).
 334 .TP
 335 .B \-4, \-\-ipv4
 336 Display only IP version 4 sockets (alias for -f inet).
 337 .TP
 338 .B \-6, \-\-ipv6
 339 Display only IP version 6 sockets (alias for -f inet6).
 340 .TP
 341 .B \-0, \-\-packet
 342 Display PACKET sockets (alias for -f link).
 343 .TP
 344 .B \-t, \-\-tcp
 345 Display TCP sockets.
 346 .TP
 347 .B \-u, \-\-udp
 348 Display UDP sockets.
 349 .TP
 350 .B \-d, \-\-dccp
 351 Display DCCP sockets.
 352 .TP
 353 .B \-w, \-\-raw
 354 Display RAW sockets.
 355 .TP
 356 .B \-x, \-\-unix
 357 Display Unix domain sockets (alias for -f unix).
 358 .TP
 359 .B \-S, \-\-sctp
 360 Display SCTP sockets.
 361 .TP
 362 .B \-\-vsock
 363 Display vsock sockets (alias for -f vsock).
 364 .TP
 365 .B \-\-xdp
 366 Display XDP sockets (alias for -f xdp).
 367 .TP
 368 .B \-f FAMILY, \-\-family=FAMILY
 369 Display sockets of type FAMILY.  Currently the following families are
 370 supported: unix, inet, inet6, link, netlink, vsock, xdp.
 371 .TP
 372 .B \-A QUERY, \-\-query=QUERY, \-\-socket=QUERY
 373 List of socket tables to dump, separated by commas. The following identifiers
 374 are understood: all, inet, tcp, udp, raw, unix, packet, netlink, unix_dgram,
 375 unix_stream, unix_seqpacket, packet_raw, packet_dgram, dccp, sctp,
 376 vsock_stream, vsock_dgram, xdp Any item in the list may optionally be
 377 prefixed by an exclamation mark
 378 .RB ( ! )
 379 to exclude that socket table from being dumped.
 380 .TP
 381 .B \-D FILE, \-\-diag=FILE
 382 Do not display anything, just dump raw information about TCP sockets
 383 to FILE after applying filters. If FILE is - stdout is used.
 384 .TP
 385 .B \-F FILE, \-\-filter=FILE
 386 Read filter information from FILE.  Each line of FILE is interpreted
 387 like single command line option. If FILE is - stdin is used.
 388 .TP
 389 .B FILTER := [ state STATE-FILTER ] [ EXPRESSION ]
 390 Please take a look at the official documentation for details regarding filters.
 391
 392 .SH STATE-FILTER
 393
 394 .B STATE-FILTER
 395 allows to construct arbitrary set of states to match. Its syntax is
 396 sequence of keywords state and exclude followed by identifier of
 397 state.
 398 .TP
 399 Available identifiers are:
 400
 401 All standard TCP states:
 402 .BR established ", " syn-sent ", " syn-recv ", " fin-wait-1 ", " fin-wait-2 ", " time-wait ", " closed ", " close-wait ", " last-ack ", "
 403 .BR  listening " and " closing.
 404
 405 .B all
 406 - for all the states
 407
 408 .B connected
 409 - all the states except for
 410 .BR listening " and " closed
 411
 412 .B synchronized
 413 - all the
 414 .B connected
 415 states except for
 416 .B syn-sent
 417
 418 .B bucket
 419 - states, which are maintained as minisockets, i.e.
 420 .BR time-wait " and " syn-recv
 421
 422 .B big
 423 - opposite to
 424 .B bucket
 425
 426 .SH USAGE EXAMPLES
 427 .TP
 428 .B ss -t -a
 429 Display all TCP sockets.
 430 .TP
 431 .B ss -t -a -Z
 432 Display all TCP sockets with process SELinux security contexts.
 433 .TP
 434 .B ss -u -a
 435 Display all UDP sockets.
 436 .TP
 437 .B ss -o state established '( dport = :ssh or sport = :ssh )'
 438 Display all established ssh connections.
 439 .TP
 440 .B ss -x src /tmp/.X11-unix/*
 441 Find all local processes connected to X server.
 442 .TP
 443 .B ss -o state fin-wait-1 '( sport = :http or sport = :https )' dst 193.233.7/24
 444 List all the tcp sockets in state FIN-WAIT-1 for our apache to network
 445 193.233.7/24 and look at their timers.
 446 .TP
 447 .B ss -a -A 'all,!tcp'
 448 List sockets in all states from all socket tables but TCP.
 449 .SH SEE ALSO
 450 .BR ip (8),
 451 .br
 452 .BR RFC " 793 "
 453 - https://tools.ietf.org/rfc/rfc793.txt (TCP states)
 454
 455 .SH AUTHOR
 456 .I ss
 457 was written by Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>.
 458 .PP
 459 This manual page was written by Michael Prokop <mika@grml.org>
 460 for the Debian project (but may be used by others).