Arch Linux

zx

Member

Registered: 2014-09-17

Posts: 22

[SOLVED] Some ports are ready to use after some time (22, 53)

Hi,

I have some standalone machine with few services, one of them is:
- bind/named on port 53 tcp
- ssh on port 22
- nfs server on few other default ports

Machine boot up really fast, but some ports are not opened (maybe not in use) for some time. I mean about port 22, 53.
I have to wait for some time (more then minute) and then somehow they are ready to use.

I have iptables rules, but ports are opened. And I can log into machine after some time.

I used nmap to see what ports are open, and right after boot Ive got this result:

$ sudo nmap -Pn 192.168.123.254
Starting Nmap 7.70 ( https://nmap.org ) at 2019-01-30 14:24 CET
Nmap scan report for 192.168.123.254
Host is up (0.00045s latency).
Not shown: 999 closed ports
PORT    STATE SERVICE
111/tcp open  rpcbind
MAC Address: 74:D4:35:1E:0F:ED (Giga-byte Technology)

Nmap done: 1 IP address (1 host up) scanned in 0.37 second

As I mention, after some time everything looks good:

$ sudo nmap -Pn 192.168.123.254
Starting Nmap 7.70 ( https://nmap.org ) at 2019-01-30 14:24 CET
Nmap scan report for 192.168.123.254
Host is up (0.00040s latency).
Not shown: 997 closed ports
PORT    STATE SERVICE
22/tcp  open  ssh
53/tcp  open  domain
111/tcp open  rpcbind
MAC Address: 74:D4:35:1E:0F:ED (Giga-byte Technology)

Nmap done: 1 IP address (1 host up) scanned in 0.34 seconds

Why this problem looks strange?
Because when I log into machine directly over tty1 for example.
Then everything is ready to go, and I dont have to wait some time.

Any idea why is this happening, and how to fix it?

Last edited by zx (2019-01-30 15:08:54)

jasonwryan

Anarchist

From: .nz

Registered: 2009-05-09

Posts: 30,424

Website

Re: [SOLVED] Some ports are ready to use after some time (22, 53)

Install and run haveged and see if that changes.

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zx

Member

Registered: 2014-09-17

Posts: 22

Re: [SOLVED] Some ports are ready to use after some time (22, 53)

WOW @@

I will never find that alone.

Thank you very much.

ugjka

Member

From: Latvia

Registered: 2014-04-01

Posts: 1,808

Website

Re: [SOLVED] Some ports are ready to use after some time (22, 53)

I'm curious what was the actual problem and why does haveged solve it?

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zx

Member

Registered: 2014-09-17

Posts: 22

Re: [SOLVED] Some ports are ready to use after some time (22, 53)

https://wiki.archlinux.org/index.php/Haveged
??

This command shows you how much entropy your server has collected. If it is rather low (<1000), you should probably install haveged. Otherwise cryptographic applications will block until there is enough entropy available, which eg. could result in slow wlan speed, if your server is a Software access point.

Last edited by zx (2019-01-30 15:57:17)

zx

Member

Registered: 2014-09-17

Posts: 22

Re: [SOLVED] Some ports are ready to use after some time (22, 53)

If someone is interested.

My result of /proc/sys/kernel/random/entropy_avail is about 240 and grew up in the time. That value is without enabled haveged.
After started haveged my entropy_avail grew up to 2400 and more.

V1del

Forum Moderator

Registered: 2012-10-16

Posts: 21,742

Re: [SOLVED] Some ports are ready to use after some time (22, 53)

I'm curious what was the actual problem and why does haveged solve it?

Relevant issues: https://bugs.archlinux.org/task/58355 https://bugzilla.redhat.com/show_bug.cgi?id=1572944#c7