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I can verify that the connection is up:

$ netstat -tn | grep ""
tcp  0  0  ESTABLISHED

is there a way to check how long this tcp port connection was up (connected)?

(No, I don't have access to app logs)

share|improve this question

You can try the following:

  1. get the PID (say $pid) of the program by adding the -p option to netstat.

  2. identify the proper line in the /proc/net/tcp file by looking at the local_address and/or rem_address fields (note that they are in hex format, specifically the IP address is expressed in little-endian byte order), also make sure that the st is 01 (for ESTABLISHED);

  3. note the associated inode field (say $inode);

  4. search for that inode among the file descriptors in /proc/$pid/fd and finally query the file access time of the symbolic link:

    find /proc/$pid/fd -lname "socket:\[$inode\]" -printf %t

That is a grunt work... here's a script (stub) to automatize the above points, it requires the remote address and it prints the socket uptime in seconds:

function suptime() {
    local addr=${1:?Specify the remote IPv4 address}
    local port=${2:?Specify the remote port number}
    # convert the provided address to hex format
    local hex_addr=$(python -c "import socket, struct; print(hex(struct.unpack('<L', socket.inet_aton('$addr'))[0])[2:10].upper().zfill(8))")
    local hex_port=$(python -c "print(hex($port)[2:].upper().zfill(4))")
    # get the PID of the owner process
    local pid=$(netstat -ntp 2>/dev/null | awk '$6 == "ESTABLISHED" && $5 == "'$addr:$port'"{sub("/.*", "", $7); print $7}')
    [ -z "$pid" ] && { echo 'Address does not match' 2>&1; return 1; }
    # get the inode of the socket
    local inode=$(awk '$4 == "01" && $3 == "'$hex_addr:$hex_port'" {print $10}' /proc/net/tcp)
    [ -z "$inode" ] && { echo 'Cannot lookup the socket' 2>&1; return 1; }
    # query the inode status change time
    local timestamp=$(find /proc/$pid/fd -lname "socket:\[$inode\]" -printf %T@)
    [ -z "$timestamp" ] && { echo 'Cannot fetch the timestamp' 2>&1; return 1; }
    # compute the time difference
    LANG=C printf '%s (%.2fs ago)\n' "$(date -d @$timestamp)" $(bc <<<"$(date +%s.%N) - $timestamp")

(Edit thanks to Alex for the fixes)


$ suptime 80
Thu Dec 24 16:22:58 CET 2015 (46.12s ago)
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This recipe displays age of process that created TCP connection, not connection itself. – myroslav Dec 24 '15 at 13:17
@myroslav are you sure? It works against this Node.js script. – cYrus Dec 24 '15 at 15:33
I'd tested your new script with TCP connections opened by my Firefox on Fedora 22 64-bit, and I'm getting definitely not "uptime" numbers. When new socket opens, it is getting "random" uptime, usually the time of "youngest" ESTABLISHED socket. – myroslav Dec 25 '15 at 23:23
@myroslav I'm using Debian (3.16.0-4-amd64) here, the only thing I notice is that the time reported is actually about 3 seconds late with respect to the socket creation. Maybe there are some system-dependent behaviors involved... – cYrus Dec 26 '15 at 11:21

The script by cYrus worked for me but i had to fix it a bit (to get rid of a "L" in the hex address and to make port a 4 digit hex):

--- suptime.orig    2015-08-20 15:46:12.896652464 +0200
+++ suptime 2015-08-20 15:47:48.560074728 +0200
@@ -7,8 +7,8 @@
     hex_addr=$(python -c "
 import socket, struct;
 print hex(struct.unpack('<L',
-    hex_port=$(python -c "print hex($port)[2:].upper()")
+    hex_port=$(python -c "print hex($port)[2:].upper().zfill(4)")
     inode=$(awk '$3 == "'$hex_addr:$hex_port'" {print $10}' /proc/net/tcp)
     time=$(find /proc/$pid/fd -lname "socket:\[$inode\]" -printf %A@)
     LANG=C printf '%.2fs' $(bc <<<"$(date +%s.%N) - $time")
share|improve this answer

This questions was helpful to me, but I found using lsof instead of netstat let me avoid all the HEX stuff:

For a process ${APP} run by user ${USER}, the following returns all the open sockets to the IP address ${IP}:

PEEID=$(sudo pgrep -u ${USER} ${APP}) && for i in `sudo lsof -anP -i -u logstash | grep ${IP} | awk '{print $6}'` ; do echo "${device} time" ; sudo find /proc/${PEEID}/fd -lname "socket:\[${device}\]" -printf %t 2> /dev/null  ; echo  ;  done

The lsof contains the PID too, but I am not sure how to get it and the device number.

This was tested on Amazon Linux.

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I haven’t seen netstat give that information. A combination of netstat and ps commands should be helpful.

  • Get pid of the socket with netstat.
$ sudo netstat -plan | grep ""

tcp        0      0       ESTABLISHED 2679/chromium-brows
  • Check process details with ps.
$ sudo ps -eo uid,pid,etime | grep 2679

1000  2679       44:31

The third value here is the total time the socket has been running.

To understand ps output better I am pasting the headings.

$  sudo ps -eo uid,pid,etime | head

0     1       52:37
share|improve this answer
if you do this on the sever side, this will give you how long the server was running. I am interested in how long the connection is up. Say the server started last month but the client connected only 2 days ago. In this case, on the server I get "one month" but I am looking for "2 days". – hidralisk Mar 14 '13 at 23:12
This will in fact tell you how long the connection is up. I think only detailed logging will be able to tell how long the client was connected to the socket. This is definitely a lead. – paintbox Mar 15 '13 at 6:31
This will give you how much time the process has been up, not the socket. – fons Dec 9 '15 at 19:58

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