Install nmap and check which ports are open.Centos 7

yum install nmap

now scan the ports with :

nmap -sT -O localhost

result:

Nmap scan report for localhost (127.0.0.1)

Host is up (0.000083s latency).

rDNS record for 127.0.0.1: localhost.localdomain

Not shown: 972 closed ports

PORT      STATE SERVICE

21/tcp    open  ftp

22/tcp    open  ssh

25/tcp    open  smtp

53/tcp    open  domain

80/tcp    open  http

110/tcp   open  pop3

111/tcp   open  rpcbind

143/tcp   open  imap

443/tcp   open  https

783/tcp   open  spamassassin

993/tcp   open  imaps

995/tcp   open  pop3s

1080/tcp  open  socks

1081/tcp  open  pvuniwien

2005/tcp  open  deslogin

2009/tcp  open  news

3005/tcp  open  deslogin

3306/tcp  open  mysql

5432/tcp  open  postgresql

8009/tcp  open  ajp13

8080/tcp  open  http-proxy

8081/tcp  open  blackice-icecap

9009/tcp  open  pichat

9080/tcp  open  glrpc

9090/tcp  open  zeus-admin

9100/tcp  open  jetdirect

10024/tcp open  unknown

10025/tcp open  unknown

No exact OS matches for host (If you know what OS is running on it, see http://nmap.org/submit/ ).

TCP/IP fingerprint:

OS:SCAN(V=6.40%E=4%D=7/23%OT=21%CT=1%CU=41542%PV=N%DS=0%DC=L%G=Y%TM=59744F1

OS:C%P=x86_64-redhat-linux-gnu)SEQ(SP=101%GCD=1%ISR=105%TI=Z%TS=A)SEQ(SP=10

OS:1%GCD=1%ISR=106%TI=Z%II=I%TS=A)OPS(O1=MFFD7ST11NW7%O2=MFFD7ST11NW7%O3=MF

OS:FD7NNT11NW7%O4=MFFD7ST11NW7%O5=MFFD7ST11NW7%O6=MFFD7ST11)WIN(W1=AAAA%W2=

OS:AAAA%W3=AAAA%W4=AAAA%W5=AAAA%W6=AAAA)ECN(R=Y%DF=Y%T=40%W=AAAA%O=MFFD7NNS

OS:NW7%CC=Y%Q=)T1(R=Y%DF=Y%T=40%S=O%A=S+%F=AS%RD=0%Q=)T2(R=N)T3(R=N)T4(R=Y%

OS:DF=Y%T=40%W=0%S=A%A=Z%F=R%O=%RD=0%Q=)T5(R=Y%DF=Y%T=40%W=0%S=Z%A=S+%F=AR%

OS:O=%RD=0%Q=)T6(R=N)T7(R=Y%DF=Y%T=40%W=0%S=Z%A=S+%F=AR%O=%RD=0%Q=)U1(R=Y%D

OS:F=N%T=40%IPL=164%UN=0%RIPL=G%RID=G%RIPCK=G%RUCK=G%RUD=G)IE(R=Y%DFI=N%T=4

OS:0%CD=S)

Network Distance: 0 hops

OS detection performed. Please report any incorrect results at http://nmap.org/submit/ .

Nmap done: 1 IP address (1 host up) scanned in 12.22 seconds

now scan from external :

nmap -sT -O <ip>

result

Starting Nmap 7.50 ( https://nmap.org ) at 2017-07-23 09:30 CEST

Nmap scan report for web.site (<ip>)

Host is up (0.035s latency).

rDNS record for <ip>: mail. web.site

Not shown: 978 closed ports

PORT     STATE    SERVICE

21/tcp   open     ftp

22/tcp   open     ssh

25/tcp   open     smtp

53/tcp   open     domain

80/tcp   open     http

110/tcp  open     pop3

111/tcp  open     rpcbind

135/tcp  filtered msrpc

139/tcp  filtered netbios-ssn

143/tcp  open     imap

443/tcp  open     https

445/tcp  filtered microsoft-ds

993/tcp  open     imaps

995/tcp  open     pop3s

1080/tcp open     socks

1081/tcp open     pvuniwien

2009/tcp open     news

3306/tcp filtered mysql

8009/tcp open     ajp13

8081/tcp open     blackice-icecap

9009/tcp open     pichat

9080/tcp open     glrpc

Device type: general purpose|media device|WAP|storage-misc

Running (JUST GUESSING): Linux 3.X|4.X|2.6.X (89%), Asus embedded (86%), Synology DiskStation Manager 5.X (86%)

OS CPE: cpe:/o:linux:linux_kernel:3 cpe:/o:linux:linux_kernel:4 cpe:/o:linux:linux_kernel:3.x cpe:/h:asus:rt-n56u cpe:/o:linux:linux_kernel:3.4 cpe:/o:linux:linux_kernel:3.10 cpe:/a:synology:diskstation_manager:5.2 cpe:/o:linux:linux_kernel:2.6.32

Aggressive OS guesses: Linux 3.2 – 4.8 (89%), Linux 3.18 (88%), Linux 3.16 (87%), Linux 3.13 or 4.2 (87%), XBMCbuntu Frodo v12.2 (Linux 3.X) (87%), ASUS RT-N56U WAP (Linux 3.4) (86%), Linux 3.13 (86%), Linux 3.12 (86%), Linux 3.8 – 3.11 (86%), Linux 4.10 (86%)

No exact OS matches for host (test conditions non-ideal).

Network Distance: 6 hops

OS detection performed. Please report any incorrect results at https://nmap.org/submit/ .

Nmap done: 1 IP address (1 host up) scanned in 15.47 seconds

 

check now for LISTENING port:

Next, check for information about the port using netstat or lsof. To check for port 834 using netstat, use the following command:

netstat -anp | grep 834

result :

tcp        0      0 127.0.0.1:9168          127.0.0.1:47834         TIME_WAIT                      

unix  2      [ ACC ]     STREAM     LISTENING     397083455 343/amavisd (ch1-av  /var/spool/amavisd/amavisd.sock

unix  2      [ ]         STREAM     CONNECTED     481728342 25062/ruby           

unix  3      [ ]         STREAM     CONNECTED     407881834 4920/dovecot         

unix  2      [ ]         STREAM     CONNECTED     481808349 25062/ruby   

The lsof command reveals similar information since it is also capable of linking open ports to services:

lsof -i | grep 834

To check if the port is associated with the official list of known services, type:

cat /etc/services

 

to check the users log in use command : who

Error GET files css or js: 404 Not Found

Remove that link to your stylesheet from your index.html. You’re using the angular-cli and in your configuration, styles.css is being included by the angular-cli. Your link tag in the HTML isn’t doing anything.

(The angular cli is also dynamically injecting a link tag for that style into your html, which is why ‘it works’).

I modified my angular-cli.json :

“apps”: [
{
“root”: “src”,
“outDir”: “dist”,
“assets”: [
“assets”,
“favicon.ico”
],
“index”: “index.html”,
“main”: “main.ts”,
“polyfills”: “polyfills.ts”,
“test”: “test.ts”,
“tsconfig”: “tsconfig.app.json”,
“testTsconfig”: “tsconfig.spec.json”,
“prefix”: “app”,
“styles”: [
“styles.css”,
“select.css”
],
“scripts”: [],
“environmentSource”: “environments/environment.ts”,
“environments”: {
“dev”: “environments/environment.ts”,
“prod”: “environments/environment.prod.ts”
}
}
],

Exchange Server set up Mail and attachment size

To check your server’s current limit you can open and access them via Exchange Management Console (EMC), however PowerShell offers a faster method that is available also on Office 365. Run the following code in the Exchange Management Shell, or after connecting with Office 365 via remote PowerShell session:

get-transportconfig | ft maxsendsize, maxreceivesize
get-receiveconnector | ft name, maxmessagesize
get-sendconnector | ft name, maxmessagesize
get-mailbox Administrator |ft Name, Maxsendsize, maxreceivesize

To change the above size limits you can use a PS script too. The example below shows how to reduce the size of messages accepted by the transport service from the 25 MB to 15 MB.

Set-TransportConfig -MaxSendSize 15MB -MaxReceiveSize 15MB

Syntax of the command for send/receive connectors is similar, however you need to execute it for each connector’s identity. The same rule applies to mailboxes – you need to specify which mailboxes to affect by the command. Therefore, it is easier to pass over the result of the  Get- command directly to the Set- command. To do so – use the piping feature of PowerShell. E.g. setting a 10MB message size limit in  all mailboxes requires the following command:

Get-Mailbox | Set-Mailbox -MaxSendSize 10MB -MaxReceiveSize 10MB

The Get-mailbox command result is passed with the “|” pipe symbol to the Set-Mailbox command. This method works also for the send/receive connectors. The final script that sets the transport message size limit to 15 MB, send/receive connectors limits to 10 MB each, and the message size limit in all mailboxes to 10 MB presents as follows:

get-transportconfig | Set-TransportConfig -maxsendsize 15MB -maxreceivesize 15MB; get-receiveconnector | set-receiveconnector -maxmessagesize 10MB; get-sendconnector | set-sendconnector -maxmessagesize 10MB; get-mailbox | Set-Mailbox -Maxsendsize 10MB -maxreceivesize 10MB

There is a drawback however. Limits presented above are set for the message as a whole, no matter if they contain attachments or not. If the message is extremely large and contains no attachment, it will be stopped.

Attachment size limit

The only way to set size limits exclusively for attachments is to use a hub transport rule, which will detect and block messages if their attachments are over a specified size threshold.

To set up the rule you can use the below PowerShell script, as the method is quite simple:

New-TransportRule -Name LargeAttach -AttachmentSizeOver 10MB -RejectMessageReasonText "Message attachment size over 10MB - email rejected."

and final

Set-SendConnector -Identity “Default send connector” -MaxMessageSize 5MB

(this for all mailbox. you can use the mailbox instead ‘Default send connector’)

to check after :

get-sendconnector | ft name, maxmessagesize

very usefull this link …Thanks