procfs

https://www.kernel.org/doc/Documentation/filesystems/proc.txt

/proc/stat

cpu  493610 1050 955506 6140203935 227807 123 11036 0 0 0
cpu0 268666 64 334886 766935020 173591 1 398 0 0 0
cpu1 24279 70 87536 767591499 2804 0 329 0 0 0
cpu2 33643 371 94465 767576953 30516 19 1826 0 0 0
cpu3 35103 290 96698 767576504 2218 14 1323 0 0 0
cpu4 33836 45 97270 767592684 7115 29 2499 0 0 0
cpu5 37121 71 79464 767637237 3542 15 1788 0 0 0
cpu6 34686 62 80201 767680609 4734 35 1927 0 0 0
cpu7 26274 73 84983 767613424 3283 7 943 0 0 0
intr .......
ctxt 704806375
btime 1445592652
processes 67671
procs_running 1
procs_blocked 0
softirq 495681725 11 161892896 3202428 164102325 1327096 0 8948996 145284138 416950 10506885

cpu

• user: normal processes executing in user mode
• nice: niced processes executing in user mode
• system: processes executing in kernel mode
• idle: twiddling thumbs
• iowait: waiting for I/O to complete
• irq: servicing interrupts
• softirq: servicing softirqs
• steal: involuntary wait
• guest: running a normal guest
• guest_nice: running a niced guest

/proc/net/tcp

sl  local_address rem_address   st tx_queue rx_queue tr tm->when retrnsmt   uid  timeout inode                                                     
   0: 00000000:006F 00000000:0000 0A 00000000:00000000 00:00000000 00000000     0        0 13811 1 ffff880226d36d40 299 0 0 2 -1                     
   1: 00000000:0050 00000000:0000 0A 00000000:00000000 00:00000000 00000000     0        0 1729006482 1 ffff880111027640 299 0 0 2 -1                
   2: 00000000:0035 00000000:0000 0A 00000000:00000000 00:00000000 00000000     0        0 14961 1 ffff8802282de0c0 299 0 0 2 -1                     
   3: 00000000:0016 00000000:0000 0A 00000000:00000000 00:00000000 00000000     0        0 111764978 1 ffff880237e1f1c0 299 0 0 2 -1                 
   4: 0100007F:0019 00000000:0000 0A 00000000:00000000 00:00000000 00000000     0        0 15277 1 ffff8804296d3500 299 0 0 2 -1                     
   5: 00000000:1622 00000000:0000 0A 00000000:00000000 00:00000000 00000000   497        0 2936653873 1 ffff880261576e00 299 0 0 2 -1                
   6: E20A140A:63CD A2751DDA:0050 01 00000000:00000000 00:00000000 00000000     0        0 2864810710 1 ffff880001856980 371 4 8 10 7                
   7: E20A140A:6687 A2751DDA:0050 01 000000BC:00000000 01:00000083 00000000     0        0 2864841200 2 ffff880261435900 131 0 0 10 7                
   8: E20A140A:F722 A2751DDA:0050 08 00000000:00000001 00:00000000 00000000     0        0 2839562255 1 ffff8804296d2180 23 3 0 10 7      

0: 00000000:006F 00000000:0000 0A 
* number of entry
* local IPv4 address
* local TCP port number
* remote IPv4 address
* remote TCP port number
* connection state

00000000:00000000 00:00000000 00000000
* transmit-queue
* receive-queue
* timer_active (see below)
* number of jiffies until timer expires
* number of unrecovered RTO timeouts


0        0 13811 1 ffff880226d36d40 299 0 0 2 -1
* uid
* unanswered 0-window probes
* inode
* socket reference count
* location of socket in memory
* retransmit timeout
* (delayed ACK control data)
* Predicted tick of soft clock
* (ack.quick<<1)|ack.pingpong
* sending congestion window
* is >= 0xFFFF
* or -1 if the treshold
* slow start size threshold

/proc/net/udp

  sl  local_address rem_address   st tx_queue rx_queue tr tm->when retrnsmt   uid  timeout inode ref pointer drops             
   9: 00000000:1F94 00000000:0000 07 00000000:00000000 00:00000000 00000000    99        0 1569496407 2 ffff8802264aeb00 0     
  40: 00000000:0333 00000000:0000 07 00000000:00000000 00:00000000 00000000     0        0 13810 2 ffff8802264af800 0          
  42: 00000000:0035 00000000:0000 07 00000000:00000000 00:00000000 00000000     0        0 14960 2 ffff88022830dbc0 0          
 100: 00000000:006F 00000000:0000 07 00000000:00000000 00:00000000 00000000     0        0 13806 2 ffff8802264afb40 0 

00  "ERROR_STATUS",
01  "ESTABLISHED",
02  "SYN_SENT",
03  "SYN_RECV",
04  "FIN_WAIT1",
05  "FIN_WAIT2",
06  "TIME_WAIT",
07  "CLOSE",
08  "CLOSE_WAIT",
09  "LAST_ACK",
0A  "LISTEN",
0B  "CLOSING",