리눅스 라우팅 정보 확인 netstat -rn 명령어

리눅스 라우팅 정보 확인 netstat -rn 명령어

netstat -rn

이런 형식으로 많이들 사용합니다.


옵션을 변경하면 네트워크에서 어떤 프로토콜이 사용 중인지 알 수 있습니다.



[root@DIM ~]# netstat --help
usage: netstat [-veenNcCF] [<Af>] -r         netstat {-V|--version|-h|--help}
       netstat [-vnNcaeol] [<Socket> ...]
       netstat { [-veenNac] -I[<Iface>] | [-veenNac] -i | [-cnNe] -M | -s } [delay]

        -r, --route                display routing table
        -I, --interface=[<Iface>] display interface table for <Iface>
        -i, --interfaces           display interface table
        -g, --groups               display multicast group memberships
        -s, --statistics           display networking statistics (like SNMP)
        -M, --masquerade           display masqueraded connections

        -v, --verbose              be verbose
        -n, --numeric              don't resolve names
        --numeric-hosts            don't resolve host names
        --numeric-ports            don't resolve port names
        --numeric-users            don't resolve user names
        -N, --symbolic             resolve hardware names
        -e, --extend               display other/more information
        -p, --programs             display PID/Program name for sockets
        -c, --continuous           continuous listing

        -l, --listening            display listening server sockets
        -a, --all, --listening     display all sockets (default: connected)
        -o, --timers               display timers
        -F, --fib                  display Forwarding Information Base (default)
        -C, --cache                display routing cache instead of FIB
        -T, --notrim               stop trimming long addresses
        -Z, --context              display SELinux security context for sockets

  <Iface>: Name of interface to monitor/list.
  <Socket>={-t|--tcp} {-u|--udp} {-S|--sctp} {-w|--raw} {-x|--unix} --ax25 --ipx --netrom
  <AF>=Use '-A <af>' or '--<af>'; default: inet
  List of possible address families (which support routing):
    inet (DARPA Internet) inet6 (IPv6) ax25 (AMPR AX.25)
    netrom (AMPR NET/ROM) ipx (Novell IPX) ddp (Appletalk DDP)
    x25 (CCITT X.25)
[root@DIM ~]# man netstat
NETSTAT(8)                 Linux Programmer¡¯s Manual                NETSTAT(8)

NAME
       netstat  -  Print network connections, routing tables, interface statistics, masquerade connections, and multi-
       cast memberships

SYNOPSIS
       netstat [address_family_options] [--tcp|-t] [--udp|-u] [--raw|-w]  [--listening|-l]  [--all|-a]  [--numeric|-n]
       [--numeric-hosts][--numeric-ports][--numeric-ports]  [--symbolic|-N]  [--extend|-e[--extend|-e]]  [--timers|-o]
       [--program|-p] [--verbose|-v] [--continuous|-c] [delay]

       netstat  {--route|-r}   [address_family_options]   [--extend|-e[--extend|-e]]   [--verbose|-v]   [--numeric|-n]
       [--numeric-hosts][--numeric-ports][--numeric-ports] [--continuous|-c] [delay]

       netstat   {--interfaces|-i}   [iface]   [--all|-a]   [--extend|-e[--extend|-e]]  [--verbose|-v]  [--program|-p]
       [--numeric|-n] [--numeric-hosts][--numeric-ports][--numeric-ports] [--continuous|-c] [delay]

       netstat  {--groups|-g}  [--numeric|-n]  [--numeric-hosts][--numeric-ports][--numeric-ports]   [--continuous|-c]
       [delay]

       netstat   {--masquerade|-M}  [--extend|-e]  [--numeric|-n]  [--numeric-hosts][--numeric-ports][--numeric-ports]
       [--continuous|-c] [delay]

       netstat {--statistics|-s} [--tcp|-t] [--udp|-u] [--raw|-w] [delay]

       netstat {--version|-V}

       netstat {--help|-h}

       address_family_options:

       [--protocol={inet,unix,ipx,ax25,netrom,ddp}[,...]]   [--unix|-x]  [--inet|--ip]  [--ax25]  [--ipx]   [--netrom]
       [--ddp]

DESCRIPTION
       Netstat prints information about the Linux networking subsystem.  The type of information printed is controlled
       by the first argument, as follows:

   (none)
       By default, netstat displays a list of open sockets.  If you don¡¯t  specify  any  address  families,  then  the
       active sockets of all configured address families will be printed.

   --route , -r
       Display the kernel routing tables.

   --groups , -g
       Display multicast group membership information for IPv4 and IPv6.

   --interface=iface , -i
       Display a table of all network interfaces, or the specified iface).

   --masquerade , -M
       Display a list of masqueraded connections.

   --statistics , -s
       Display summary statistics for each protocol.

OPTIONS
   --verbose , -v
       Tell  the  user  what is going on by being verbose. Especially print some useful information about unconfigured
       address families.

   --numeric , -n
       Show numerical addresses instead of trying to determine symbolic host, port or user names.

   --numeric-hosts
       shows numerical host addresses but does not affect the resolution of port or user names.

   --numeric-ports
       shows numerical port numbers but does not affect the resolution of host or user names.

   --numeric-users
       shows numerical user IDs but does not affect the resolution of host or port names.

   --protocol=family , -A
       Specifies the address families (perhaps better described as low level protocols) for which connections  are  to
       be  shown.   family  is  a  comma  (¡¯,¡¯)  separated list of address family keywords like inet, unix, ipx, ax25,
       netrom, and ddp.  This has the same effect as using the --inet, --unix (-x), --ipx, --ax25, --netrom, and --ddp
       options.

       The address family inet includes raw, udp and tcp protocol sockets.

   -c, --continuous
       This will cause netstat to print the selected information every second continuously.

   -e, --extend
       Display additional information.  Use this option twice for maximum detail.

   -o, --timers
       Include information related to networking timers.

   -p, --program
       Show the PID and name of the program to which each socket belongs.

   -l, --listening
       Show only listening sockets.  (These are omitted by default.)

   -a, --all
       Show  both  listening  and  non-listening  sockets.  With the --interfaces option, show interfaces that are not
       marked

   -F
       Print routing information from the FIB.  (This is the default.)

   -C
       Print routing information from the route cache.

   -Z --context
       If SELinux enabled print SELinux context.

   -T --notrim
       Stop trimming long addresses.

   delay
       Netstat will cycle printing through statistics every delay seconds.  UP.

OUTPUT
   Active Internet connections (TCP, UDP, raw)
   Proto
       The protocol (tcp, udp, raw) used by the socket.

   Recv-Q
       The count of bytes not copied by the user program connected to this socket.

   Send-Q
       The count of bytes not acknowledged by the remote host.

   Local Address
       Address and port number of the local end of the socket.  Unless the --numeric (-n)  option  is  specified,  the
       socket address is resolved to its canonical host name (FQDN), and the port number is translated into the corre-
       sponding service name.

   Foreign Address
       Address and port number of the remote end of the socket.  Analogous to "Local Address."

   State
       The state of the socket. Since there are no states in raw mode and usually no states used in UDP,  this  column
       may be left blank. Normally this can be one of several values:

       ESTABLISHED
              The socket has an established connection.

       SYN_SENT
              The socket is actively attempting to establish a connection.

       SYN_RECV
              A connection request has been received from the network.

       FIN_WAIT1
              The socket is closed, and the connection is shutting down.

       FIN_WAIT2
              Connection is closed, and the socket is waiting for a shutdown from the remote end.

       TIME_WAIT
              The socket is waiting after close to handle packets still in the network.

       CLOSED The socket is not being used.

       CLOSE_WAIT
              The remote end has shut down, waiting for the socket to close.

       LAST_ACK
              The remote end has shut down, and the socket is closed. Waiting for acknowledgement.

       LISTEN The  socket  is  listening for incoming connections.  Such sockets are not included in the output unless
              you specify the --listening (-l) or --all (-a) option.

       CLOSING
              Both sockets are shut down but we still don¡¯t have all our data sent.

       UNKNOWN
              The state of the socket is unknown.

   User
       The username or the user id (UID) of the owner of the socket.

   PID/Program name
       Slash-separated pair of the process id (PID) and process name of the process that owns the  socket.   --program
       causes  this column to be included.  You will also need superuser privileges to see this information on sockets
       you don¡¯t own.  This identification information is not yet available for IPX sockets.

   Timer
       (this needs to be written)

   Active UNIX domain Sockets
   Proto
       The protocol (usually unix) used by the socket.

   RefCnt
       The reference count (i.e. attached processes via this socket).

   Flags
       The flags displayed is SO_ACCEPTON (displayed as ACC), SO_WAITDATA (W) or SO_NOSPACE (N).  SO_ACCECPTON is used
       on  unconnected sockets if their corresponding processes are waiting for a connect request. The other flags are
       not of normal interest.

   Type
       There are several types of socket access:

       SOCK_DGRAM
              The socket is used in Datagram (connectionless) mode.

       SOCK_STREAM
              This is a stream (connection) socket.

       SOCK_RAW
              The socket is used as a raw socket.

       SOCK_RDM
              This one serves reliably-delivered messages.

       SOCK_SEQPACKET
              This is a sequential packet socket.

       SOCK_PACKET
              Raw interface access socket.

       UNKNOWN
              Who ever knows what the future will bring us - just fill in here :-)

   State
       This field will contain one of the following Keywords:

       FREE   The socket is not allocated

       LISTENING
              The socket is listening for a connection request.  Such sockets are only included in the output  if  you
              specify the --listening (-l) or --all (-a) option.

       CONNECTING
              The socket is about to establish a connection.

       CONNECTED
              The socket is connected.

       DISCONNECTING
              The socket is disconnecting.

       (empty)
              The socket is not connected to another one.

       UNKNOWN
              This state should never happen.

   PID/Program name
       Process  ID  (PID)  and  process  name  of the process that has the socket open.  More info available in Active
       Internet connections section written above.

   Path
       This is the path name as which the corresponding processes attached to the socket.

   Active IPX sockets
       (this needs to be done by somebody who knows it)

   Active NET/ROM sockets
       (this needs to be done by somebody who knows it)

   Active AX.25 sockets
       (this needs to be done by somebody who knows it)

NOTES
       Starting with Linux release 2.2 netstat -i does not show interface statistics for alias interfaces. To get  per
       alias interface counters you need to setup explicit rules using the ipchains(8) command.

FILES
       /etc/services -- The services translation file

       /proc -- Mount point for the proc filesystem, which gives access to kernel status information via the following
       files.

       /proc/net/dev -- device information

       /proc/net/raw -- raw socket information

       /proc/net/tcp -- TCP socket information

       /proc/net/udp -- UDP socket information

       /proc/net/igmp -- IGMP multicast information

       /proc/net/unix -- Unix domain socket information

       /proc/net/ipx -- IPX socket information

       /proc/net/ax25 -- AX25 socket information

       /proc/net/appletalk -- DDP (appletalk) socket information

       /proc/net/nr -- NET/ROM socket information

       /proc/net/route -- IP routing information

       /proc/net/ax25_route -- AX25 routing information

       /proc/net/ipx_route -- IPX routing information

       /proc/net/nr_nodes -- NET/ROM nodelist

       /proc/net/nr_neigh -- NET/ROM neighbours

       /proc/net/ip_masquerade -- masqueraded connections

       /proc/net/snmp -- statistics

SEE ALSO
       route(8), ifconfig(8), ipchains(8), iptables(8), proc(5)

BUGS
       Occasionally strange information may appear if a socket changes as it is viewed. This is unlikely to occur.

AUTHORS
       The netstat user interface was written by Fred  Baumgarten  <dc6iq@insu1.etec.uni-karlsruhe.de>  the  man  page
       basically by Matt Welsh <mdw@tc.cornell.edu>. It was updated by Alan Cox <Alan.Cox@linux.org> but could do with
       a bit more work.  It was updated again by Tuan Hoang <tqhoang@bigfoot.com>.
       The man page and the command included in  the  net-tools  package  is  totally  rewritten  by  Bernd  Eckenfels
       <ecki@linux.de>.

net-tools                      19 December 2000                     NETSTAT(8)
[root@DIM ~]#
[root@DIM ~]#
[root@DIM ~]#
[root@DIM ~]# netstat -rn
Kernel IP routing table
Destination     Gateway         Genmask         Flags   MSS Window  irtt Iface
211.104.100.0   0.0.0.0         255.255.255.0   U         0 0          0 eth0
10.1.1.0        0.0.0.0         255.255.255.0   U         0 0          0 eth1
10.1.2.0        0.0.0.0         255.255.255.0   U         0 0          0 eth2
10.1.3.0        0.0.0.0         255.255.255.0   U         0 0          0 eth3