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ssh生成私钥格式可选择PKCS8/PEM/SSH2，使用ssh-keygen生成PEM格式私钥：

ssh-keygen -t rsa -P "passwd" -b 4096 -C Haiyun -m PEM -f ~/.ssh/id_rsa

转换私钥格式为PKCS8或SSH2：

ssh-keygen -P "passwd" -N "passwd" -e -p -m PKCS8 -f ~/.ssh/id_rsa
ssh-keygen -P "passwd" -N "passwd" -e -p -m SSH2 -f ~/.ssh/id_rsa

从ssh私钥生成openssl可识别的公钥：

ssh-keygen -e -m PKCS8 -f ~/.ssh/id_rsa > ~/.ssh/id_rsa.pub.pkcs8
openssl rsa -in ~/.ssh/id_rsa -pubout -outform PEM > ~/.ssh/id_rsa.pub.pkcs8

openssl使用公私钥加解密：

openssl rsautl -encrypt -pubin -inkey ~/.ssh/id_rsa.pub.pkcs8 -ssl -in test.txt -out test.enc
openssl rsautl -decrypt -inkey ~/.ssh/id_rsa -in test.enc -out test.dec

删除qemu-guest-agent软件包：

systemctl stop qemu-guest-agent     
apt-get autoremove --purge qemu-guest-agent -y 

qemu-guest-agent通过virtio_console内核模块建立的虚拟设备和服务器交互：

/dev/virtio-ports/org.qemu.guest_agent.0
/dev/vport1p1

卸载并禁用virtio_console模块：

rmmod virtio_console 
echo "blacklist virtio_console" >> /etc/modprobe.d/blacklist.conf

登录ssh时将agent sock链接到固定文件：

cat << EOF > ~/.ssh/rc 
#!/bin/bash
if [ -S "\$SSH_AUTH_SOCK" ]; then
    ln -sf \$SSH_AUTH_SOCK ~/.ssh/ssh_auth_sock
fi
EOF
chmod +x ~/.ssh/rc 

tmux更新SSH_AUTH_SOCK变量：

cat << EOF >> ~/.tmux.conf 
#先删除SSH_AUTH_SOCK变量，不然设置无效
set -g -u update-environment[3]
setenv -g 'SSH_AUTH_SOCK' ~/.ssh/ssh_auth_sock
EOF

dropbear可使用此方法：

alias ssh='[ -n "$TMUX" ] && [ -n $SSH_AUTH_SOCK ] && eval $(tmux showenv -s SSH_AUTH_SOCK); /usr/bin/ssh'
alias scp='[ -n "$TMUX" ] && [ -n $SSH_AUTH_SOCK ] && eval $(tmux showenv -s SSH_AUTH_SOCK); /usr/bin/scp'

https://stackoverflow.com/questions/21378569/how-to-auto-update-ssh-agent-environment-variables-when-attaching-to-existing-tm

tc只能对网卡出口(egress)方向限速，如果是单机限制下载速度需将入(ingress)定向到虚拟接口出，然后使用虚拟ifb接口对下载限速。
在限制上传速度时可以直接使用iptables mark数据包，但是下载的时候ingress在iptables mark之前，需要在出的时候对流量mark并save，tc在定向流量到虚拟接口的时候添加connmark。

#!/bin/bash
set -x
#上传限速，使用hfsc模式
tc qdisc del dev eth0 root
tc qdisc add dev eth0 root handle 1: hfsc default 20
tc class add dev eth0 parent 1:0 classid 1:20 hfsc sc rate 1000mbit ul rate 1000mbit
tc class add dev eth0 parent 1:0 classid 1:21 hfsc sc rate 40mbit ul rate 50mbit
#使用htb模式限速
#tc qdisc add dev eth0 root handle 1: htb default 20
#tc class add dev eth0 parent 1:0 classid 1:20 htb rate 1000mbit
#tc class add dev eth0 parent 1:20 classid 1:21 htb rate 40mbit ceil 50mbit
#给限速队列添加随机公平
#tc qdisc add dev eth0 parent 1:20 handle 20: sfq perturb 10
#tc qdisc add dev eth0 parent 1:21 handle 21: sfq perturb 10
#iptables mark 21使用class 1:21
tc filter add dev eth0 parent 1:0 prio 1 handle 21 fw flowid 1:21

#下载限速
modprobe ifb numifbs=1
ip link set dev ifb0 up
tc qdisc del dev eth0 ingress
tc qdisc add dev eth0 handle ffff: ingress
tc filter add dev eth0 parent ffff: u32 match u32 0 0 action connmark \
action mirred egress redirect dev ifb0
tc qdisc del dev ifb0 root
#tc qdisc add dev ifb0 root handle 2: hfsc default 20
#tc class add dev ifb0 parent 2:0 classid 2:20 hfsc sc rate 1000mbit ul rate 1000mbit
#tc class add dev ifb0 parent 2:0 classid 2:21 hfsc sc rate 80mbit ul rate 80mbit

tc qdisc add dev ifb0 root handle 2: htb default 20
tc class add dev ifb0 parent 2:0 classid 2:20 htb rate 1000mbit
tc class add dev ifb0 parent 2:0 classid 2:21 htb rate 80mbit

#直接使用tc限制特定ip，无需iptables mark
#tc filter add dev ifb0 parent 2:0 protocol ip prio 0 u32 match ip dst 192.168.1.2 flowid 2:21
#tc filter add dev ifb0 parent 2:0 protocol ipv6 prio 0 u32 match ip6 dst 2408::/16 flowid 2:21

tc filter add dev ifb0 parent 2:0 prio 0 handle 21 fw flowid 2:21

iptables -t mangle -F
iptables -t mangle -X
ip6tables -t mangle -F
ip6tables -t mangle -X

iptables -t mangle -A OUTPUT -m owner --uid-owner user -o eth0 -p tcp -m multiport --dport 80,443 -j RETURN
iptables -t mangle -A OUTPUT -m owner --uid-owner user -o eth0 -d 192.168.1.0/24 -j RETURN
iptables -t mangle -A OUTPUT -m owner --uid-owner user -o eth0 -j CONNMARK --restore-mark
iptables -t mangle -A OUTPUT -m owner --uid-owner user -o eth0 -m mark ! --mark 0 -j ACCEPT
iptables -t mangle -A OUTPUT -m owner --uid-owner user -o eth0 -j MARK --set-mark 21
iptables -t mangle -A OUTPUT -j CONNMARK --save-mark
ip6tables -t mangle -A OUTPUT -m owner --uid-owner user -o eth0 -j CONNMARK --restore-mark
ip6tables -t mangle -A OUTPUT -m owner --uid-owner user -o eth0 -m mark ! --mark 0 -j ACCEPT
ip6tables -t mangle -A OUTPUT -p tcp --dport 443 -j MARK --set-mark 21
ip6tables -t mangle -A OUTPUT -j CONNMARK --save-mark

查看：

tc -s qdisc show dev eth0
tc -s qdisc show dev eth0 root
tc -s qdisc show dev eth0 ingress
tc -s class show dev eth0 
tc -s filter show dev eth0 

参考：
https://blog.csdn.net/i_scream_/article/details/82776333

下载mips musl交叉编译环境，也可以使用https://toolchains.bootlin.com/。

wget https://musl.cc/mips-linux-musl-cross.tgz
tar zxf mips-linux-musl-cross.tgz
export PATH=$PATH:`pwd`/mips-linux-musl-cross/bin/

编译ncurses，后续要将/lib/terminfo/x/xterm-256color等复制到目标机器/data/terminfo目录，不然运行tmux提示找不到terminfo database。

wget https://ftp.gnu.org/pub/gnu/ncurses/ncurses-6.4.tar.gz
tar zxf ncurses-6.4.tar.gz
cd ncurses-6.4/
./configure --prefix /usr/local/tmux --with-default-terminfo-dir=/data/terminfo --enable-pc-files --host=mips-linux-musl
#解决错误:strip: Unable to recognise the format of the input file `/usr/local/tmux/bin/tic'
ln -s `pwd`/../mips-linux-musl-cross/bin/mips-linux-musl-strip /usr/local/bin/strip
make && make install
rm -rf /usr/local/bin/strip

编译libevent和tmux：

wget https://github.com/libevent/libevent/releases/download/release-2.1.12-stable/libevent-2.1.12-stable.tar.gz
tar zxf libevent-2.1.12-stable.tar.gz 
cd libevent-2.1.12-stable/
./configure --prefix /usr/local/tmux --host=mips-linux-musl --disable-openssl
make && make install

wget https://github.com/tmux/tmux/releases/download/3.3a/tmux-3.3a.tar.gz
tar zxf tmux-3.3a.tar.gz 
cd tmux-3.3a/
export CFLAGS="-I/usr/local/tmux/include -I/usr/local/tmux/include/ncurses"
export LDFLAGS="-L/usr/local/tmux/lib"
./configure --enable-static --prefix=/usr/local/tmux --host=mips-linux-musl
make && make install

静态编译dropbear，当前最新版本使用SRT关闭窗口后dropbear和执行的命令一直在后台不结束，使用dropbear-2020.81版本正常。

wget https://github.com/mkj/dropbear/archive/refs/tags/DROPBEAR_2022.83.tar.gz
tar zxf DROPBEAR_2022.83.tar.gz 
cd dropbear-DROPBEAR_2022.83/
./configure --enable-static --prefix=/usr/local/dropbear --host=mips-linux-musl --disable-zlib --disable-syslog --disable-harden --disable-lastlog --disable-utmp --disable-utmpx --disable-wtmp --disable-wtmpx --disable-pututline --disable-pututxline --disable-loginfunc 
PROGRAMS="dropbear dbclient dropbearkey dropbearconvert scp" MULTI=1 make strip

编译前可修改default_options.h定义dropbear运行时的PATH用来查找scp执行文件，sftp-server执行文件路径使用SFTP。

#define SFTPSERVER_PATH "/data/bin/sftp-server"
#define DROPBEAR_PATH_SSH_PROGRAM "/data/bin/dbclient"
#define DEFAULT_ROOT_PATH "/usr/sbin:/usr/bin:/sbin:/bin:/data/bin"
#define DEFAULT_PATH "/usr/bin:/bin:/data/bin"

编译的为单个文件dropbearmulti，使用时创建软链接：

ln -s /data/bin/dropbearmulti /data/bin/dropbear
ln -s /data/bin/dropbearmulti /data/bin/dropbearkey 
ln -s /data/bin/dropbearmulti /data/bin/scp     

静态编译openssl/openssh/sshd：

wget https://www.zlib.net/zlib-1.2.13.tar.gz
tar zxf zlib-1.2.13.tar.gz 
cd zlib-1.2.13/
CC=mips-linux-musl-gcc  ./configure --prefix=/usr/local/openssh --static 
make && make install

wget https://github.com/openssl/openssl/releases/download/OpenSSL_1_1_1t/openssl-1.1.1t.tar.gz
tar zxf openssl-1.1.1t.tar.gz 
cd openssl-1.1.1t
#./config no-asm no-shared --prefix=/usr/local/openssh --cross-compile-prefix=mips-linux-musl-
#sed -i 's/-m64//g' Makefile
./Configure linux-mips32 no-asm no-shared --prefix=/usr/local/openssh --cross-compile-prefix=mips-linux-musl-
make && make install

export CFLAGS="-I/usr/local/openssh/include/"
export LDFLAGS="-L/usr/local/openssh/lib/"
wget https://cdn.openbsd.org/pub/OpenBSD/OpenSSH/portable/openssh-9.3p1.tar.gz
tar zxf openssh-9.3p1.tar.gz 
cd openssh-9.3p1/
./configure --prefix=/usr/local/openssh --host=mips-linux-musl --with-ldflags=-static --disable-lastlog --disable-utmp  --disable-utmpx --disable-wtmp  --disable-wtmpx --disable-libutil --disable-pututline --disable-pututxline --with-default-path=/usr/bin:/bin:/usr/sbin:/sbin:/sbin:/usr/sbin:/bin:/usr/bin:/data/bin
make && make install

静态编译bash:

wget https://ftp.gnu.org/gnu/bash/bash-5.1.tar.gz
tar zxf bash-5.1.tar.gz 
cd bash-5.1/
./configure --enable-static-link --host=mips-linux-musl --without-bash-malloc
make
mips-linux-musl-strip -s bash

静态编译iperf3：

wget https://github.com/esnet/iperf/releases/download/3.15/iperf-3.15.tar.gz
tar zxf iperf-3.15.tar.gz 
cd iperf-3.15/
./configure --prefix=/usr/local/iperf3 --host=mips-linux-musl "LDFLAGS=--static" --disable-shared 
make

静态编译dnsmasq:

wget https://thekelleys.org.uk/dnsmasq/dnsmasq-2.89.tar.gz
tar zxf dnsmasq-2.89.tar.gz 
cd dnsmasq-2.89/
CC=mips-linux-musl-gcc make CFLAGS=-Os LDFLAGS=-static