# CSA Midterm Note
Created: November 6, 2023 12:07 PM
Tags: freebsd, freebsdcmd, freebsdcommand, portsnap
## Midterm
“I copied it”
windows
ac, pw 都是”csa”
website: [http://csa.cs.nthu.edu.tw/](http://csa.cs.nthu.edu.tw/)
### 常用command
```bash
vi /etc/ssh/sshd_config
PermitRootLogin yes
PasswordAuthentication yes
```
### 25/9
netstat -rn >> check ipv4, ipv6 setting
cat /etc/passwd → passward file
診斷上唔到網問題
check VMware bridging
ssh to VM
gen key
hw: 10/10 deadline
upload pem key file
upload server 來的ppg 檔,轉做pem 檔by putty keygen
search: freebsd keygen, freebsd authorized key
## 2/10
1. install portsnap
```bash
portsnap fetch
portsnap extract
# normal to run for 10+ minutes
cd /usr/ports/ports-mgmt/portmaster
# intall portmaster
make; make install; make clean
```
other useful command
```jsx
pkg help
pkg list # list what package i have
pkg search <name> # search open src pkg
pkg remove <name>
```
default dir for package
- usr/local
- usr/local/sbin → admin package
1. Apache Web Server
2.
```jsx
# 1. install by package
pkg search apache | grep web
# find relevent pkg
pkg install apache24
# start service
service apache24 start
# 2. install by source
# 2.1 update os
freebsd-update fetch
freebsd-update install
cd usr/ports/www/apache24
# see video for how to start service
service apache24 start
ps auwwwx | grep http
# check is http service started
```
chnage setting
vi httpd.conf
document root = home page address
go to root
add / homework.txt
make the IP public
host ip: my ip
port 80
guest ip
; 10.2.1.1
# how to get public IP
1. host have public IP → NAT- > port fw
how to get public IP in host?
install SSL VPN/ othervpn
### Authorize login to server by SSH key
how to generate SSH key and cpoy into server?
[How To Configure SSH Key-Based Authentication on a FreeBSD Server | DigitalOcean](https://www.digitalocean.com/community/tutorials/how-to-configure-ssh-key-based-authentication-on-a-freebsd-server)
```bash
# login into ssh (default is login with pw)
ssh -p <port number> username@virtual_machine_ip
#logout
exit
#login with ssh key
ssh -p <port number> -i <key file e.g. xxx_id_rsa> username@virtual_machine_ip
# copy ssh key to server manually
cat ~/.ssh/<public_key.pub> | ssh -p <port> username@virtual_machine_ip "mkdir -p ~/.ssh && cat >> ~/.ssh/authorized_keys"
# this create dir ~/.ssh/authorized_keys, and copy the .pub file to it
ssh-cpoy-id seems not work for freebsd
# generate .pem file from public key
ssh-keygen -f xxx_id_rsa -e -m pem
# generate private key file in .pem format (won't see the .pem file extension)
ssh-keygen -t rsa -m PEM # -m to specify format
```
## 16/10
```bash
top
>>> show即時行兝資料
nice -> 排程相關
```
**top**
這畫面時按鍵盤=command
e.g. 按→ 開mannual
ps auwx |grep syslog
睇pid
```bash
w
>>> show all logged in user
```
w
### syslogd
```bash
service syslogd start # start syslogd
service syslogd restart
# syslogd 每次restart log 就會重新紀錄
```
open a new log file
touch /var/log/logfilename.log
**[to check]** broadcast emerg message
### alias
**系統設定檔**
/etc/csh.cshrc
**個人設定檔**
~/.cshrc
**set 環境變數path**
set path = (/dir/dri/….)
don’t delete default existing path!!
or will loss all command
path 入面排前=high priority
### cgi
### make a custom cgi
用途: 令server可以收query & print something on the browser
### enable cgi in apache
edit /usr/local/etc/aphache24/httpd.conf
add this
```bash
LoadModule cgi_module libexec/apache24/mod_cgi.so
```
by default 已有test-cgi & printenv 兩個cgi in /usr/local/
### Add / Edit cgi
go to /usr/local/www/apache24/cgi-bin
**create a simple cgi**
```bash
joe simple-cgi
```
## 23/10
```bash
drill AAAA csa.cs.nthu.edu.tw # lookup IPv6 addr
#see P.4 of http://csa.cs.nthu.edu.tw/bind.pdf
drill -x # 反查
#e.g.
drill -x 140.114.140.86.1
-> =揾drill 1.86.114.140.in-addr.arpa -> 入面的TR
```
### my 網域
go here regisrer my domain (done)
[http://csa.cs.nthu.edu.tw/cgi-bin/cgiwrap/root/dns/admin](http://csa.cs.nthu.edu.tw/cgi-bin/cgiwrap/root/dns/admin)
rali.csa.cs.nthu.edu.tw
**how to check is my domain up?**
go to cmd in host machine
nslookup -type=SOA <my-domane, e.g. rali.csa.cs.nthu.edu.tw>
睇有冇answer
then
nslookup -type=NS rali.csa.cs.nthu.edu.tw
config
dns 120 IN A 140.114.252.84 # 代表dns.<my-domain> 指到40.114.252.84
@ 120 IN A 140.114.252.84 # 代表<my-domain>指到40.114.252.84
set up
1. go to /usr/local/etc/namedb/named.conf =⇒ 最後set master 檔
```bash
// /usr/local/etc/namedb/named.conf
// add this to end
zone "rali.csa.cs.nthu.edu.tw" {
type master;
file "/usr/local/etc/namedb/primary/rali.csa.cs.nthu.edu.tw.hosts";
//this is kind of file, can be any file name, for clear purpose set
//it to the ip
};
//comment listen-on 127.0.0
```
2. create this file
/usr/local/etc/namedb/primary/rali.csa.cs.nthu.edu.tw.hosts (correct version)
**第3行 ;below 2 每次update完都要加大
```bash
$TTL 120
$ORIGIN rali.csa.cs.nthu.edu.tw.
@ 120 IN SOA rali.csa.cs.nthu.edu.tw. mhlee.c.zohomail.eu. (2 30 30 30
@ 120 IN NS rali.csa.cs.nthu.edu.tw.
;dns.rali.csa.cs.nthu.edu.tw. 120 IN A 140.114.252.24
dns 120 IN A 140.114.252.24
@ 120 IN A 140.114.252.24
;above is my ip
;This is a comment
www 120 IN A 140.114.252.24
www2 120 IN A 140.114.86.1
homework 120 IN AAAA 2001:288:e001:86:1::1
hw 120 CNAME csa.cs.nthu.edu.tw.
www.rali.csa.cs.nthu.edu.tw. IN CAA 0 issue ";"
www.rali.csa.cs.nthu.edu.tw. IN CAA 0 issuewild "letsencrypt.org"
```
port fw
host port 53 fw to guest port 53 both TCP & UDP
### HW5
create 根態證,upload
search 憑證parsing tool
## 30/1
hw4
- create cert from a website
- load module related to ssl
- pem file path to somewhere????
```bash
```
hw5: upload server.key
follow [http://csa.cs.nthu.edu.tw/ssl/](http://csa.cs.nthu.edu.tw/ssl/)
## VM ports & port forwarding
default ports
port 22 - ssh login
port 80 - browser
port forwarding example
local port 50→ VM port 80 = 打local’s ip port 50→去VM browser
- e.g. my port forwarding is local’s ip port 50 → VM’s port 22
- login 要打ssh -p 50 <username>@local’s ip
local port 8080 → VM port 22 = 打local’s ip port 8080 → ssh login to VM
- e.g. my port forwarding is local’s ip port 8080 → VM’s port 80
- browser 睇VM’ apache 要打 <local’s ip>:8080
-
如browser 去左ssh port or vice versa → 出error: kex_exchange_identification
browser 打ip 冇打port → by default 即port 80
e.g.
- 140.11.252.93:80 →140.11.252.93’s port 80
- 140.11.252.93 → 無specify port → browser default 去port 80→ 140.11.252.93’s port 80
ssh 一定要打port
[to fix]
now run any custom script 出
已set path, chmod 755,r don’t know why this happening
# Internal Server Error
The server encountered an internal error or
misconfiguration and was unable to complete
your request.
Please contact the server administrator at
you@example.com to inform them of the time this error occurred,
and the actions you performed just before this error.
More information about this error may be available
in the server error log.
Sign in with Wallet
Connect another wallet