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-> 6.7.8.9: 43698 (ESTABLISHED)Root TCP 1.2.3.4: 22-> 6.7.8.9: 44943 (ESTABLISHED)Huangwei TCP 1.2.3.4: 22-> 6.7.8.9: 44943 (ESTABLISHED)Huangwei TCP 1.2.3.4: 38038-> 74.125.227.20: www (ESTABLISHED)Let's see who is using a large number of concurrent connections? DDoS? Website administrator's nightmare! A "simple" command can be used to find the script kids? You can see: $ Sudo netstat-anp | grep 'tcp \ | udp' | awk '{print $5}' | cut-d:-f1 | sort | uniq-c | sort-nr8 192.168.0.2187 192.168.0.386
1. What isIPv6 IPV6 refers to the Internet Protocol (IP) version 6th. At present, we mainly use Internet Protocol Fourth edition, namely IPv4. With the global Internet highly developed today, IPV4 address resources have dried up and the internet is undergoing a transition from IPV4 network to IPV6 network. The IPV4 add
Perl Unicode conversion Overview: 1. Determine the encoding method of the Input Source2. The input source is UTF-8 encoded.A. encode: _ utf8_on ($ Str); Enable utf8 flag.The input source is not UTF-8 encoded.A. $ string = decode (encoding, $ octets [, check]); convert the input source to utf8 encoding and enable utf8 flag3. Output$ STR = encode: encoding (encoding, $ Str); encodes a string from utf8 to the specified encoding, and disables utf8 flag.
1071, the checksum calculation is done in the following way: (1) adjacent octets to be checksummed are already red to Form 16-bit integers, and the 1's complement sum of these 16-bit integers is formed. (2) To generate a Checksum, the checksum field itself is cleared, the 16-bit 1's complement sum is computed over the octets concerned, and the 1's complement of this sum is placed in the checksum field. (3)
email information #!/usr/bin/envpythonimportgetpass,poplib,sys(host,user)=sys.argv[1:]passwd=getpass.getpass()p=poplib.POP3(host)try:print‘AttemptingAPOPauthentication‘p.apop(user,passwd)exceptpoplib.error_proto:print‘Attemptingstandardauthentication‘try:p.user(user)p.pass_(passwd)exceptpoplib.error_proto,e:print‘Loginfailed:‘,esys.exit(1)status=p.stat()print‘Mailboxhas%dmessagesforatotalof%dbytes‘%(status[0],status[1])foriteminp.list()[1]:number,octets
Depending on the deployment speed of the existing IPV4 address, the remaining address will be exhausted in 10-20 years. Therefore, the network gradually from IPV4 to IPv6 conversion is inevitable, the corresponding various network applications will support IPV6. For Java, starting from its 1.4 version of the IPV6 to provide better support, the programmer has basically shielded the differences between
large number of concurrent connections? DDoS? Website administrator's nightmare! A "simple" command can be used to find the script kids? You can see: $ Sudo netstat-anp | grep 'tcp \ | udp' | awk '{print $5}' | cut-d:-f1 | sort | uniq-c | sort-nr8 192.168.0.2187 192.168.0.386 192.168.0.146 0.0.0.02 192.168.0.1662 192.168.0.1102 192.168.0.101 192.168.232.2231 192.168.0.701 192.168.0.61 192.168.0.501 192.168.0.221 192.168.0.2101 192.168.0.194How many ports are opened on the server? You can see: $
Hrstorageram indicates memory, hrstoragefixeddisk indicates hard disk, hrstoragevirtualmemory indicates virtual memory, and hrstoragecompactdisc indicates Disc 2. differentiate Disk/partition types 1.3.6.1.2.1.25.2.3.1.2.1 = 1.3.6.1.2.1.25.2.1.4 [objectidentifier] // Hard Disk1.3.6.1.2.1.25.2.3.1.2.2 = 1.3.6.1.2.1.25.2.1.4 [objectidentifier] // Hard Disk1.3.6.1.2.1.25.2.3.1.2.3 = 1.3.6.1.2.1.25.2.1.4 [objectidentifier] // Hard Disk1.3.6.1.2.1.25.2.3.1.2.4 = 1.3.6.1.2.1.25.2.1.4 [objectidentif
, and allow the traffic of other virtual channels to pass without interruption. This method allows the network to create a service without packet loss category for a single virtual link, so that it can coexist with other traffic types on the same interface. In fact, PFC is an enhancement of the common traffic control function.Message format:As defined in 802.1qbb, the format of the PFC frame is as follows: + ---------------- + ----------------- + | Destination MAC address (6
indicates hard disk, hrstoragevirtualmemory indicates virtual memory, and hrstoragecompactdisc indicates Disc2. differentiate Disk/partition types1.3.6.1.2.1.25.2.3.1.2.1 = 1.3.6.1.2.1.25.2.1.4 [objectidentifier] // Hard Disk1.3.6.1.2.1.25.2.3.1.2.2 = 1.3.6.1.2.1.25.2.1.4 [objectidentifier] // Hard Disk1.3.6.1.2.1.25.2.3.1.2.3 = 1.3.6.1.2.1.25.2.1.4 [objectidentifier] // Hard Disk1.3.6.1.2.1.25.2.3.1.2.4 = 1.3.6.1.2.1.25.2.1.4 [objectidentifier] // Hard Disk1.3.6.1.2.1.25.2.3.1.2.5 = 1.3.6.1.2.
first, the basic conceptISATAP (intra-siteautomatic Tunnel addressing Protocol)ISATAP is a very easy to deploy and use IPV6 transition mechanism. In a IPv4 network, we can very easily ISATAP deployment, first of all your PC needs to be v4/v6 dual-stack pc, then, need to have a support ISATAP router, ISATAP router can be anywhere in the network, as long as the PC can ping it (of course, You need to know the IPV4
Server Optimization-Sysctl, Apache, and MySQL-Linux Enterprise Application-Linux server application information. For more information, see the following section. It is often said that the load capacity of the server depends largely on the configuration and optimization capabilities of the system administrator. This is correct. The same hardware and different software configurations will produce very different results. The following describes how to optimize sysctrl, Apache, and MySQL. Note that
The Netsh Interface Portproxy command provides the Netsh Interface Portproxy command for the Management Server that acts as a proxy between IPv4 and IPv6 networks and applications. You can use these commands to create a proxy service: Send IPv4-configured computers and application messages to other IPv4-configured computers and applications. Send messages from co
The load capacity of the server depends largely on the configuration and optimization capabilities of the system administrator. The same hardware and different software configurations will produce very different results. The following describes how to optimize sysctrl, Apache, and MySQL. Note that all configurations depend on individual users. make adjustments based on your actual situation. Configure Sysctl edit ApacheMySQL optimization The load capacity of the server depends largely on the c
bytes ). 131071 513920/proc/sys/net/core/netdev_max_backlog maximum number of packets that can be sent to the queue when each network interface receives packets at a rate faster than the rate at which the kernel processes these packets. 1000 2000/proc/sys/net/core/somaxconn defines the maximum length of the listening queue for each port in the system. this is a global parameter. 128 2048/proc/sys/net/core/optmem_max indicates the maximum buffer size allowed by each socket. 20480 81920/proc/sys/
system. This is a global parameter. 128 2048/proc/sys/net/core/optmem_max indicates the maximum buffer size allowed by each socket. 20480 81920/proc/sys/net/ipv4/tcp_mem determine how the TCP stack reflects memory usage. The unit of each value is a memory page (usually 4 kb ). The first value is the lower limit of memory usage, the second value is the upper limit of the application pressure on the buffer zone starting from the memory pressure mode, a
the screen, read and save files, etc.) when not directly using the Perl string, but the need to convert the Perl string into a byte stream, the conversion process to use which encoding is entirely dependent on you (or by Perl). Once the Perl string is encoded into the byte stream, the concept of the character does not exist, and it becomes a pure grouping of bytes, and it is your job to explain these combinations. We can see that if we want Perl to use our character concepts to treat text, the
/wmem_max Maximum TCP data transmission window (in bytes ). 131071 513920 /Proc/sys/NET/CORE/netdev_max_backlog The maximum number of packets that can be sent to the queue when each network interface receives packets faster than the kernel processes these packets. 1000 2000 /Proc/sys/NET/CORE/somaxconn Defines the maximum length of the listening queue for each port in the system. This is a global parameter. 128 2048 /Proc/s
Copyleft of this document belongs to yfydz and can be freely copied and reproduced when published using GPL. It is strictly prohibited to be used for any commercial purposes.MSN: yfydz_no1@hotmail.comSource: http://yfydz.cublog.cn 1. 5 mount pointsThe following kernel code version is 2.6.17.11.1.1 preroting/* Net/IPv4/ip_input.c */Int ip_rcv (struct sk_buff * SKB, struct net_device * Dev, struct packet_type * PT, struct net_device * orig_dev){......Re
: * LISTEN 27709/java tcp 0 0 0.0.0.0: 4200 0.0.0.0: * LISTEN-tcp 0 0 0.0.0.0: 58666 0.0.0.0: * LISTEN-tcp 0 0.0.0.0: 845 0.0.0.0: * LISTEN-tcp 0 0 0.0.0.0: 4110 0.0.0.0: * LISTEN-tcp 0 0 0.0.0.0: 4207 0.0.0.0: * LISTEN-tcp 0 0.0.0.0: 111 0.0.0.0: * LISTEN-tcp 0 0 0.0.0.0: 20880 0.0.0.0: * LISTEN-tcp 0 0 0.0.0.0: 4208 0.0.0.0: * LISTEN-tcp 0 0 0.0. 0.0: 18000 0.0.0.0: * LISTEN-tcp 0 0.0.0.0: 18001 0.0.0.0: * LISTEN-tcp 0 0 0.0.0.0: 18002 0.0.0.0: * LISTEN-tcp 0 0 0.0.0.0: 42483 0.0.0.0: * LISTEN
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