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    WillieBy Updated:No Comments4 Mins Read

    NAME

    ss – another utility to investigate sockets  

    SYNOPSIS

    ss [options] [ FILTER ]  

    DESCRIPTION

    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.

     

    OPTIONS

    When no option is used ss displays a list of open non-listening TCP sockets that have established connection.
    -h, –help
    Show summary of options.
    -V, –version
    Output version information.
    -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.
    -e, –extended
    Show detailed socket information
    -m, –memory
    Show socket memory usage.
    -p, –processes
    Show process using socket.
    -i, –info
    Show internal TCP information.
    -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.
    -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).
    -f FAMILY, –family=FAMILY
    Display sockets of type FAMILY. Currently the following families are supported: unix, inet, inet6, link, netlink.
    -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.
    -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 TCP-STATE ] [ EXPRESSION ]
    Please take a look at the official documentation (Debian package iproute-doc) for details regarding filters.
     

    USAGE EXAMPLES

    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.
     

    Willie has over 15 years of experience in Linux system administration and DevOps. After managing infrastructure for startups and enterprises alike, he founded Command Linux to share the practical knowledge he wished he had when starting out. He oversees content strategy and contributes guides on server management, automation, and security.

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