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+.\" Copyright (C) 1994, 1995, Daniel Quinlan <quinlan@yggdrasil.com>
+.\" Copyright (C) 2002-2008, 2017, Michael Kerrisk <mtk.manpages@gmail.com>
+.\" Copyright (C) , Alan Cox <A.Cox@swansea.ac.uk>
+.\" Copyright (C) 2023, Alejandro Colomar <alx@kernel.org>
+.\"
+.\" SPDX-License-Identifier: GPL-3.0-or-later
+.\"
+.TH proc_pid_net 5 2023-08-15 "Linux man-pages 6.7"
+.SH NAME
+/proc/pid/net/, /proc/net/ \- network layer information
+.SH DESCRIPTION
+.TP
+.IR /proc/ pid /net/ " (since Linux 2.6.25)"
+See the description of
+.IR /proc/net .
+.TP
+.I /proc/net/
+This directory contains various files and subdirectories containing
+information about the networking layer.
+The files contain ASCII structures and are,
+therefore, readable with
+.BR cat (1).
+However, the standard
+.BR netstat (8)
+suite provides much cleaner access to these files.
+.IP
+With the advent of network namespaces,
+various information relating to the network stack is virtualized (see
+.BR network_namespaces (7)).
+Thus, since Linux 2.6.25,
+.\" commit e9720acd728a46cb40daa52c99a979f7c4ff195c
+.I /proc/net
+is a symbolic link to the directory
+.IR /proc/self/net ,
+which contains the same files and directories as listed below.
+However, these files and directories now expose information
+for the network namespace of which the process is a member.
+.TP
+.I /proc/net/arp
+This holds an ASCII readable dump of the kernel ARP table used for
+address resolutions.
+It will show both dynamically learned and preprogrammed ARP entries.
+The format is:
+.IP
+.in +4n
+.EX
+IP address HW type Flags HW address Mask Device
+192.168.0.50 0x1 0x2 00:50:BF:25:68:F3 * eth0
+192.168.0.250 0x1 0xc 00:00:00:00:00:00 * eth0
+.EE
+.in
+.IP
+Here "IP address" is the IPv4 address of the machine and the "HW type"
+is the hardware type of the address from RFC\ 826.
+The flags are the internal
+flags of the ARP structure (as defined in
+.IR /usr/include/linux/if_arp.h )
+and
+the "HW address" is the data link layer mapping for that IP address if
+it is known.
+.TP
+.I /proc/net/dev
+The dev pseudo-file contains network device status information.
+This gives
+the number of received and sent packets, the number of errors and
+collisions
+and other basic statistics.
+These are used by the
+.BR ifconfig (8)
+program to report device status.
+The format is:
+.IP
+.EX
+Inter\-| Receive | Transmit
+ face |bytes packets errs drop fifo frame compressed multicast|bytes packets errs drop fifo colls carrier compressed
+ lo: 2776770 11307 0 0 0 0 0 0 2776770 11307 0 0 0 0 0 0
+ eth0: 1215645 2751 0 0 0 0 0 0 1782404 4324 0 0 0 427 0 0
+ ppp0: 1622270 5552 1 0 0 0 0 0 354130 5669 0 0 0 0 0 0
+ tap0: 7714 81 0 0 0 0 0 0 7714 81 0 0 0 0 0 0
+.EE
+.\" .TP
+.\" .I /proc/net/ipx
+.\" No information.
+.\" .TP
+.\" .I /proc/net/ipx_route
+.\" No information.
+.TP
+.I /proc/net/dev_mcast
+Defined in
+.IR /usr/src/linux/net/core/dev_mcast.c :
+.IP
+.in +4n
+.EX
+indx interface_name dmi_u dmi_g dmi_address
+2 eth0 1 0 01005e000001
+3 eth1 1 0 01005e000001
+4 eth2 1 0 01005e000001
+.EE
+.in
+.TP
+.I /proc/net/igmp
+Internet Group Management Protocol.
+Defined in
+.IR /usr/src/linux/net/core/igmp.c .
+.TP
+.I /proc/net/rarp
+This file uses the same format as the
+.I arp
+file and contains the current reverse mapping database used to provide
+.BR rarp (8)
+reverse address lookup services.
+If RARP is not configured into the
+kernel,
+this file will not be present.
+.TP
+.I /proc/net/raw
+Holds a dump of the RAW socket table.
+Much of the information is not of
+use
+apart from debugging.
+The "sl" value is the kernel hash slot for the
+socket,
+the "local_address" is the local address and protocol number pair.
+\&"St" is
+the internal status of the socket.
+The "tx_queue" and "rx_queue" are the
+outgoing and incoming data queue in terms of kernel memory usage.
+The "tr", "tm\->when", and "rexmits" fields are not used by RAW.
+The "uid"
+field holds the effective UID of the creator of the socket.
+.\" .TP
+.\" .I /proc/net/route
+.\" No information, but looks similar to
+.\" .BR route (8).
+.TP
+.I /proc/net/snmp
+This file holds the ASCII data needed for the IP, ICMP, TCP, and UDP
+management
+information bases for an SNMP agent.
+.TP
+.I /proc/net/tcp
+Holds a dump of the TCP socket table.
+Much of the information is not
+of use apart from debugging.
+The "sl" value is the kernel hash slot
+for the socket, the "local_address" is the local address and port number pair.
+The "rem_address" is the remote address and port number pair
+(if connected).
+\&"St" is the internal status of the socket.
+The "tx_queue" and "rx_queue" are the
+outgoing and incoming data queue in terms of kernel memory usage.
+The "tr", "tm\->when", and "rexmits" fields hold internal information of
+the kernel socket state and are useful only for debugging.
+The "uid"
+field holds the effective UID of the creator of the socket.
+.TP
+.I /proc/net/udp
+Holds a dump of the UDP socket table.
+Much of the information is not of
+use apart from debugging.
+The "sl" value is the kernel hash slot for the
+socket, the "local_address" is the local address and port number pair.
+The "rem_address" is the remote address and port number pair
+(if connected).
+"St" is the internal status of the socket.
+The "tx_queue" and "rx_queue" are the outgoing and incoming data queue
+in terms of kernel memory usage.
+The "tr", "tm\->when", and "rexmits" fields
+are not used by UDP.
+The "uid"
+field holds the effective UID of the creator of the socket.
+The format is:
+.IP
+.EX
+sl local_address rem_address st tx_queue rx_queue tr rexmits tm\->when uid
+ 1: 01642C89:0201 0C642C89:03FF 01 00000000:00000001 01:000071BA 00000000 0
+ 1: 00000000:0801 00000000:0000 0A 00000000:00000000 00:00000000 6F000100 0
+ 1: 00000000:0201 00000000:0000 0A 00000000:00000000 00:00000000 00000000 0
+.EE
+.TP
+.I /proc/net/unix
+Lists the UNIX domain sockets present within the system and their
+status.
+The format is:
+.IP
+.EX
+Num RefCount Protocol Flags Type St Inode Path
+ 0: 00000002 00000000 00000000 0001 03 42
+ 1: 00000001 00000000 00010000 0001 01 1948 /dev/printer
+.EE
+.IP
+The fields are as follows:
+.RS
+.TP 10
+.IR Num :
+the kernel table slot number.
+.TP
+.IR RefCount :
+the number of users of the socket.
+.TP
+.IR Protocol :
+currently always 0.
+.TP
+.IR Flags :
+the internal kernel flags holding the status of the socket.
+.TP
+.IR Type :
+the socket type.
+For
+.B SOCK_STREAM
+sockets, this is 0001; for
+.B SOCK_DGRAM
+sockets, it is 0002; and for
+.B SOCK_SEQPACKET
+sockets, it is 0005.
+.TP
+.IR St :
+the internal state of the socket.
+.TP
+.IR Inode :
+the inode number of the socket.
+.TP
+.IR Path :
+the bound pathname (if any) of the socket.
+Sockets in the abstract namespace are included in the list,
+and are shown with a
+.I Path
+that commences with the character '@'.
+.RE
+.TP
+.I /proc/net/netfilter/nfnetlink_queue
+This file contains information about netfilter user-space queueing, if used.
+Each line represents a queue.
+Queues that have not been subscribed to
+by user space are not shown.
+.IP
+.in +4n
+.EX
+ 1 4207 0 2 65535 0 0 0 1
+ (1) (2) (3)(4) (5) (6) (7) (8)
+.EE
+.in
+.IP
+The fields in each line are:
+.RS 7
+.TP 5
+(1)
+The ID of the queue.
+This matches what is specified in the
+.B \-\-queue\-num
+or
+.B \-\-queue\-balance
+options to the
+.BR iptables (8)
+NFQUEUE target.
+See
+.BR iptables\-extensions (8)
+for more information.
+.TP
+(2)
+The netlink port ID subscribed to the queue.
+.TP
+(3)
+The number of packets currently queued and waiting to be processed by
+the application.
+.TP
+(4)
+The copy mode of the queue.
+It is either 1 (metadata only) or 2
+(also copy payload data to user space).
+.TP
+(5)
+Copy range; that is, how many bytes of packet payload should be copied to
+user space at most.
+.TP
+(6)
+queue dropped.
+Number of packets that had to be dropped by the kernel because
+too many packets are already waiting for user space to send back the mandatory
+accept/drop verdicts.
+.TP
+(7)
+queue user dropped.
+Number of packets that were dropped within the netlink
+subsystem.
+Such drops usually happen when the corresponding socket buffer is
+full; that is, user space is not able to read messages fast enough.
+.TP
+(8)
+sequence number.
+Every queued packet is associated with a (32-bit)
+monotonically increasing sequence number.
+This shows the ID of the most recent packet queued.
+.RE
+.IP
+The last number exists only for compatibility reasons and is always 1.
+.SH SEE ALSO
+.BR proc (5)