A TLS Reverse Proxy for SNI and ALPN routing.

Supports both static and dynamic TLS routing.

go run ./cmd/tlsrouter/ \
   --config ~/.config/tlsrouter/backends.csv \
   --vault ~/.config/tlsrouter/secrets.tsv \
   --ip-domains vm.example.com \
   --networks 192.168.1.0/24 \
   --bind 0.0.0.0 \
   --port 443

Configured backends are loaded statically, while URLs like https://tls-192-168-1-100.vm.example.com are dynamically proxied - provided that the ip domain and ip-as-subdomain addresses match the allowed domain and networks.

Sites are configured through DNS.

Both http/1.1 and ssh (terminated) can be enabled by setting a CNAME to the direct IP domain:

# terminates https to 3080
CNAME   site-a.whatever.com  tls-192-168-1-100.vm.example.net   300

# proxies non-terminated to 443
CNAME   site-a.whatever.com  tcp-192-168-1-100.vm.example.net   300

If you'd like to use a CNAME for convenience for multiple records, use cname.<ip-domain>, such as cname.vm.example.net.

CNAME   sites.whatever.com               cname.vm.example.net   300

Note: all ports in the table below are public and you should bind to localhost or use a firewall if you wish to run things on those ports privately.

A                  whatever.com                              123.1.2.3  300
SRV     _http._tcp.whatever.com     10 3080 tls-10-11-1-123.a.bnna.net  300 10
SRV      _ssh._tcp.whatever.com     10   22 tls-10-11-1-123.a.bnna.net  300 10

Note: ports must be selected according to the table below. Arbitrary ports are not allowed for security reasons (anyone can set records on their domain to your IP address).

Whether using CNAME or A records, SRV records will enable additional proxying.

SRV             _h2._tcp.whatever.com   10  443 tcp-10-11-1-123.a.bnna.net  300 10
SRV     _postgresql._tcp.whatever.com   10 3080 tls-10-11-1-123.a.bnna.net  300 10

ALPN names can be translated to service names in one of two ways:

1. replace all . (periods) with -, and replace / with _
2. drop anything after / and replace all . (periods) with -

For example: http and http_1-1 are both valid for http/1.1

Note: ports must be selected according to the table below. Arbitrary ports are not allowed for security reasons (anyone can set records on their domain to your IP address).

The URL pattern is There are two URL patterns:

• <layer4>-<ipv4-octets>-<ip-domain>
• tls-192-168-1-100.example.com (Handles / Terminates TLS)
• tcp-192-168-1-100.example.com (Raw TCP Passthrough / Non-Terminating)

ALL TRAFFIC uses port 443 externally.

If the Raw TCP URL is used, then the Raw Port will be used - proxied traffic will remain encrypted.

If the Terminating URL is used, then the Decrypted Port will be used.

Why non-standard ports? So that unencrypted services, which may have been intended for private networking, aren't exposed to the Internet by default.

ALPN	Raw Port	Decrypted Port	Comment
http/1.1	443	3080	3080 to be familiar, but non-default like 3000, 8080, and 80
ssh	44322	22	sshd can't handle sclient tls directly, hence 44322 for tls
---	---	---	special protocols
acme-tls/1	443	-	for ACME / Let's Encrypt TLS SNI ALPN challenges
h2	443	-	proper HTTP/2 requires raw passthrough and has no plain port
h2c	-	3080	plain HTTP/2, for testing/debugging
---	---	---	10,000 is added to the default ports below
coap	5684	15683	IoT, plain port is 5683
dicom	2762	10104	biomedical imaging, plain port is 104
dot	853	10053	dns-over-tls, normal plain port is 53 (udp and tcp)
ftp	990	10021	normal plain port is 21, but it's more complicated than that
imap	993	10143	normal plain port is 143
irc	6697	16667	normal plain port is 6667
managesieve	4190	14190	for mail filtering, plain is also 4190
mqtt	8883	11883	normal plain port is 1883
nntp	563	10119	for News Servers, plain port is 119
ntske/1	4460	10123	for NTP, normal plain port is 123
pop3	995	10110	normal plain port is 110
postgresql	5432	15432	Postgres 17+ supports direct TLS
tds/8.0	1433	11433	MS SQL 2025+ supports direct TLS
radius/1.0	2083	12083	legacy TLS optional
radius/1.1	2083	12083	direct TLS required
sip	5061	15060	normal plain port is 5060 (or 5080)
smb	10445	10445	Either use requires tunneling (native SMB TLS requires QUIC)
webrtc	443	10080	10080 to be familiar, but not 18080, 8080, 8081, or 9000
c-webrtc	443	10080	"
xmpp-client	5223	15222	client-to-server communication, default 5222 (plain)
xmpp-server	5270	15269	server-to-server communication, default 5269 (plain)

For all registered ALPNs, see https://www.iana.org/assignments/tls-extensiontype-values/tls-extensiontype-values.xhtml.

Excluded:

• co is UDP-only
• doq DNS over QUIC is UDP-only
• http/0.9, http/1.0 superseded by http/1.1
• h3 HTTP over QUIC is UDP-only
• nnsp has no port designation (and isn't actually referenced in the RFC)
• spdy/* superseded by h2
• stun.turn has more complex implications that I'm ready to consider
• stun.nat-discovery (same)
• sunrpc probably not relevant