网络相关 – Hev's Blog

VirtManager connect remote service

Network TSO/GSO

From: https://www.cnblogs.com/codestack/p/14890786.html

OpenWrt: Set policy routing

function put_route() {
    ip route del default dev pppoe-wanct proto static table 100
    ip route add default dev pppoe-wanct proto static table 100
    ip rule del pref 32760
    ip rule add pref 32760 from ${1} lookup 100
}

put_route ${ip}

SSH: Use legacy SCP protocol

Issue

/usr/libexec/sftp-server: not found

-O      Use the legacy SCP protocol for file transfers instead of the SFTP protocol.  Forcing the use of the SCP protocol may be necessary for servers that do not implement SFTP, for backwards-compatibility for particular filename wildcard patterns and for expanding paths with a ‘~’ prefix for older SFTP servers.

Block QUIC

nftables

udp dport { 80, 443 } reject with icmpx port-unreachable

iptables

-p udp --match multiport --dports 80,443 -j REJECT

Systemd network DHCP and Static at same time

/etc/systemd/network/eth0.network

[Match]
Name=eth0

[Network]
DHCP=yes

[Address]
Address=104.21.64.95/32

[Address]
Address=2606:4700:3037::ac43::1/64

IPv6 support some protocol-specific socket options that can be set with setsockopt and read with getsockopt. The socket option level for IPv6 is IPPROTO_IPV6. A boolean integer flag is zero with it is false, otherwise true.

IPV6_V6ONLY

If this flag is set to true (nonzero), then the socket is restricted to sending and receiving IPv6 packets only. In this case, an IPv4 and an IPv6 application can bind to a single port at the same time.

If this flag is set to false (zero), then the socket can be used to send and receive packets to and from an IPv6 address or an IPv4-mapped IPv6 address.

The argument is a pointer to a boolean value in an integer.

The default value for this flag is defined by the contents of the file /proc/sys/net/ipv6/bindv6only. The default value for that file is 0 (false).

Example

int one = 1;
setsockopt (fd, IPPROTO_IPV6, IPV6_V6ONLY, &one, sizeof (one));

Refer to: https://man7.org/linux/man-pages/man7/ipv6.7.html

IP addr-label persistent by systemd

This is an example shows how to make IP address label persistent by systemd-networkd.

/etc/systemd/network/eth0.network :

[Match]
Name=eth0

[Network]
Address=192.168.0.1/24
Gateway=192.168.0.254
DNS=192.168.0.254

[IPv6AddressLabel]
Label=100
Prefix=2409::/16

[IPv6AddressLabel]
Label=100
Prefix=2606::/16

It’s successful if you can see labels that you configured :

$ ip addrl

prefix ::1/128 label 0 
prefix ::/96 label 3 
prefix ::ffff:0.0.0.0/96 label 4 
prefix 2001::/32 label 6 
prefix 2001:10::/28 label 7 
prefix 2606::/16 dev br0 label 100 
prefix 2409::/16 dev br0 label 100 
prefix 3ffe::/16 label 12 
prefix 2002::/16 label 2 
prefix fec0::/10 label 11 
prefix fc00::/7 label 5 
prefix ::/0 label 1

dnsmasq can’t resolve domains that points to reserved addresses

The dnsmasq is enables rebind protection by default, this reject DNS records that contains reserved address (RFC1918).

Remove argument to disable it:

--stop-dns-rebind

OpenWrt

LUCI

Menu: Network->DHCP and DNS

Unchecked Rebind protection.

Transparent proxy with nftables

This is an example of configuring transparent proxy(tproxy) with nftables. The tproxy application is hev-socks5-tproxy

Netfilter rules

DON’T FORGOT TO ADD UPSTREAM ADDRESS TO BYPASS IPSET!!
Or use nftables skuid/skgid match to exclude proxy process.

table inet mangle {
    set byp4 {
        typeof ip daddr
        flags interval
        elements = { 0.0.0.0/8, 10.0.0.0/8,
                 127.0.0.0/8, 169.254.0.0/16,
                 172.16.0.0/12, 192.0.0.0/24,
                 192.0.2.0/24, 192.88.99.0/24,
                 192.168.0.0/16, 198.18.0.0/15,
                 198.51.100.0/24, 203.0.113.0/24,
                 224.0.0.0/4, 240.0.0.0-255.255.255.255 }
    }

    set byp6 {
        typeof ip6 daddr
        flags interval
        elements = { ::,
                 ::1,
                 ::ffff:0:0:0/96,
                 64:ff9b::/96,
                 100::/64,
                 2001::/32,
                 2001:20::/28,
                 2001:db8::/32,
                 2002::/16,
                 fc00::/7,
                 fe80::/10,
                 ff00::-ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff }
    }

    chain prerouting {
        type filter hook prerouting priority mangle; policy accept;
        ip daddr @byp4 return
        ip6 daddr @byp6 return
        tcp dport { 0-65535 } tproxy to :1088 meta mark set 0x00000440 accept
        udp dport { 0-65535 } tproxy to :1088 meta mark set 0x00000440 accept
    }

    # Only for local mode
    chain output {
        type route hook output priority mangle; policy accept;
        ip daddr @byp4 return
        ip6 daddr @byp6 return
        tcp dport { 0-65535 } meta mark set 0x00000440
        udp dport { 0-65535 } meta mark set 0x00000440
    }
}

Routing rules

ip rule add fwmark 1088 table 100
ip route add local default dev lo table 100

ip -6 rule add fwmark 1088 table 100
ip -6 route add local default dev lo table 100

The nftables config file that bypass all IPv4 and IPv6 sets of China: https://gist.githubusercontent.com/heiher/fd001c69eda8d1f87bb66c3f44509c11/raw/nftables.conf

Category: 网络相关